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2024-06-04sysfs: Unbreak the build around sysfs_bin_attr_simple_read()Lukas Wunner1-0/+9
Günter reports build breakage for m68k "m5208evb_defconfig" plus CONFIG_BLK_DEV_INITRD=y caused by commit 66bc1a173328 ("treewide: Use sysfs_bin_attr_simple_read() helper"). The defconfig disables CONFIG_SYSFS, so sysfs_bin_attr_simple_read() is not compiled into the kernel. But init/initramfs.c references that function in the initializer of a struct bin_attribute. Add an empty static inline to avoid the build breakage. Fixes: 66bc1a173328 ("treewide: Use sysfs_bin_attr_simple_read() helper") Reported-by: Guenter Roeck <linux@roeck-us.net> Closes: https://lore.kernel.org/r/e12b0027-b199-4de7-b83d-668171447ccc@roeck-us.net Signed-off-by: Lukas Wunner <lukas@wunner.de> Tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Rafael J. Wysocki <rafael@kernel.org> Link: https://lore.kernel.org/r/05f4290439a58730738a15b0c99cd8576c4aa0d9.1716461752.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-11sysfs: Add sysfs_bin_attr_simple_read() helperLukas Wunner1-0/+15
When drivers expose a bin_attribute in sysfs which is backed by a buffer in memory, a common pattern is to set the @private and @size members in struct bin_attribute to the buffer's location and size. The ->read() callback then merely consists of a single memcpy() call. It's not even necessary to perform bounds checks as these are already handled by sysfs_kf_bin_read(). However each driver is so far providing its own ->read() implementation. The pattern is sufficiently frequent to merit a public helper, so add sysfs_bin_attr_simple_read() as well as BIN_ATTR_SIMPLE_RO() and BIN_ATTR_SIMPLE_ADMIN_RO() macros to ease declaration of such bin_attributes and reduce LoC and .text section size. Signed-off-by: Lukas Wunner <lukas@wunner.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/5ed62b197a442ec6db53d8746d9d806dd0576e2d.1712410202.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-02-23sysfs: Introduce DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE()Dan Williams1-1/+44
One of the first users of DEFINE_SYSFS_GROUP_VISIBLE() did this: static umode_t dp0_attr_visible(struct kobject *kobj, struct attribute *attr, int n) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return attr->mode; return 0; } static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SYSFS_GROUP_VISIBLE(dp0); ...i.e. the _group_visible() helper is identical to the _attr_visible() helper. Use the "simple" helper to reduce that to: static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(dp0); Remove the need to specify per attribute visibility if the goal is to hide the entire group. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/170863446625.1479840.10593839479268727913.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-02-23sysfs: Document new "group visible" helpersDan Williams1-3/+39
Add documentation and examples for how to use DEFINE_SYSFS_GROUP_VISIBLE() and SYSFS_GROUP_VISIBLE(). Recall that the motivation for this work is that it is easier to reason about the lifetime of statically defined sysfs attributes that become visible at device_add() time rather than dynamically adding them later. DEFINE_SYSFS_GROUP_VISIBLE() tackles one of the reasons to opt for dynamically created attributes which did not have a facility for hiding empty directories. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/170863446065.1479840.10697164014098377292.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-02-19sysfs: Introduce a mechanism to hide static attribute_groupsDan Williams1-12/+51
Add a mechanism for named attribute_groups to hide their directory at sysfs_update_group() time, or otherwise skip emitting the group directory when the group is first registered. It piggybacks on is_visible() in a similar manner as SYSFS_PREALLOC, i.e. special flags in the upper bits of the returned mode. To use it, specify a symbol prefix to DEFINE_SYSFS_GROUP_VISIBLE(), and then pass that same prefix to SYSFS_GROUP_VISIBLE() when assigning the @is_visible() callback: DEFINE_SYSFS_GROUP_VISIBLE($prefix) struct attribute_group $prefix_group = { .name = $name, .is_visible = SYSFS_GROUP_VISIBLE($prefix), }; SYSFS_GROUP_VISIBLE() expects a definition of $prefix_group_visible() and $prefix_attr_visible(), where $prefix_group_visible() just returns true / false and $prefix_attr_visible() behaves as normal. The motivation for this capability is to centralize PCI device authentication in the PCI core with a named sysfs group while keeping that group hidden for devices and platforms that do not meet the requirements. In a PCI topology, most devices will not support authentication, a small subset will support just PCI CMA (Component Measurement and Authentication), a smaller subset will support PCI CMA + PCIe IDE (Link Integrity and Encryption), and only next generation server hosts will start to include a platform TSM (TEE Security Manager). Without this capability the alternatives are: * Check if all attributes are invisible and if so, hide the directory. Beyond trouble getting this to work [1], this is an ABI change for scenarios if userspace happens to depend on group visibility absent any attributes. I.e. this new capability avoids regression since it does not retroactively apply to existing cases. * Publish an empty /sys/bus/pci/devices/$pdev/tsm/ directory for all PCI devices (i.e. for the case when TSM platform support is present, but device support is absent). Unfortunate that this will be a vestigial empty directory in the vast majority of cases. * Reintroduce usage of runtime calls to sysfs_{create,remove}_group() in the PCI core. Bjorn has already indicated that he does not want to see any growth of pci_sysfs_init() [2]. * Drop the named group and simulate a directory by prefixing all TSM-related attributes with "tsm_". Unfortunate to not use the naming capability of a sysfs group as intended. In comparison, there is a small potential for regression if for some reason an @is_visible() callback had dependencies on how many times it was called. Additionally, it is no longer an error to update a group that does not have its directory already present, and it is no longer a WARN() to remove a group that was never visible. Link: https://lore.kernel.org/all/2024012321-envious-procedure-4a58@gregkh/ [1] Link: https://lore.kernel.org/linux-pci/20231019200110.GA1410324@bhelgaas/ [2] Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/2024013028-deflator-flaring-ec62@gregkh Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-05kernfs: sysfs: support custom llseek method for sysfs entriesValentine Sinitsyn1-0/+2
As of now, seeking in sysfs files is handled by generic_file_llseek(). There are situations where one may want to customize seeking logic: - Many sysfs entries are fixed files while generic_file_llseek() accepts past-the-end positions. Not only being useless by itself, this also means a bug in userspace code will trigger not at lseek(), but at some later point making debugging harder. - generic_file_llseek() relies on f_mapping->host to get the file size which might not be correct for all sysfs entries. See commit 636b21b50152 ("PCI: Revoke mappings like devmem") as an example. Implement llseek method to override this behavior at sysfs attribute level. The method is optional, and if it is absent, generic_file_llseek() is called to preserve backwards compatibility. Signed-off-by: Valentine Sinitsyn <valesini@yandex-team.ru> Link: https://lore.kernel.org/r/20230925084013.309399-1-valesini@yandex-team.ru Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20driver-core: Introduce BIN_ATTR_ADMIN_{RO,RW}Ira Weiny1-0/+16
Many binary attributes need to limit access to CAP_SYS_ADMIN only; ie many binary attributes specify is_visible with 0400 or 0600. Make setting the permissions of such attributes more explicit by defining BIN_ATTR_ADMIN_{RO,RW}. Cc: Bjorn Helgaas <bhelgaas@google.com> Suggested-by: Dan Williams <dan.j.williams@intel.com> Suggested-by: Krzysztof Wilczyński <kw@linux.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Link: https://lore.kernel.org/r/20220719205249.566684-6-ira.weiny@intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2021-08-05sysfs: Rename struct bin_attribute member to f_mappingKrzysztof Wilczyński1-1/+1
There are two users of iomem_get_mapping(), the struct file and struct bin_attribute. The former has a member called "f_mapping" and the latter has a member called "mapping", and both are poniters to struct address_space. Rename struct bin_attribute member to "f_mapping" to keep both meaning and the usage consistent with other users of iomem_get_mapping(). Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Krzysztof Wilczyński <kw@linux.com> Link: https://lore.kernel.org/r/20210729233235.1508920-3-kw@linux.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-05sysfs: Invoke iomem_get_mapping() from the sysfs open callbackKrzysztof Wilczyński1-1/+1
Defer invocation of the iomem_get_mapping() to the sysfs open callback so that it can be executed as needed when the binary sysfs object has been accessed. To do that, convert the "mapping" member of the struct bin_attribute from a pointer to the struct address_space into a function pointer with a signature that requires the same return type, and then updates the sysfs_kf_bin_open() to invoke provided function should the function pointer be valid. Also, convert every invocation of iomem_get_mapping() into a function pointer assignment, therefore allowing for the iomem_get_mapping() invocation to be deferred to when the sysfs open callback runs. Thus, this change removes the need for the fs_initcalls to complete before any other sub-system that uses the iomem_get_mapping() would be able to invoke it safely without leading to a failure and an Oops related to an invalid iomem_get_mapping() access. Suggested-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Krzysztof Wilczyński <kw@linux.com> Link: https://lore.kernel.org/r/20210729233235.1508920-2-kw@linux.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-21sysfs: Add helper BIN_ATTRIBUTE_GROUPSHeiner Kallweit1-0/+6
New helper BIN_ATTRIBUTE_GROUPS() does the same as ATTRIBUTE_GROUPS(), just for binary attributes. Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> Link: https://lore.kernel.org/r/e20db248-ed30-cf5d-a37c-b538dceaa5b2@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-12sysfs: Support zapping of binary attr mmapsDaniel Vetter1-0/+2
We want to be able to revoke pci mmaps so that the same access rules applies as for /dev/kmem. Revoke support for devmem was added in 3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims the region"). The simplest way to achieve this is by having the same filp->f_mapping for all mappings, so that unmap_mapping_range can find them all, no matter through which file they've been created. Since this must be set at open time we need sysfs support for this. Add an optional mapping parameter bin_attr, which is only consulted when there's also an mmap callback, since without mmap support allowing to adjust the ->f_mapping makes no sense. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kees Cook <keescook@chromium.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Dan Williams <dan.j.williams@intel.com> Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: linux-pci@vger.kernel.org Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Sourabh Jain <sourabhjain@linux.ibm.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Nayna Jain <nayna@linux.ibm.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-12-daniel.vetter@ffwll.ch
2020-10-02sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs outputJoe Perches1-0/+15
Output defects can exist in sysfs content using sprintf and snprintf. sprintf does not know the PAGE_SIZE maximum of the temporary buffer used for outputting sysfs content and it's possible to overrun the PAGE_SIZE buffer length. Add a generic sysfs_emit function that knows that the size of the temporary buffer and ensures that no overrun is done. Add a generic sysfs_emit_at function that can be used in multiple call situations that also ensures that no overrun is done. Validate the output buffer argument to be page aligned. Validate the offset len argument to be within the PAGE_SIZE buf. Signed-off-by: Joe Perches <joe@perches.com> Link: https://lore.kernel.org/r/884235202216d464d61ee975f7465332c86f76b2.1600285923.git.joe@perches.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-01driver-core: Introduce DEVICE_ATTR_ADMIN_{RO,RW}Dan Williams1-0/+7
A common pattern for using plain DEVICE_ATTR() instead of DEVICE_ATTR_RO() and DEVICE_ATTR_RW() is for attributes that want to limit read to only root. I.e. many users of DEVICE_ATTR() are specifying 0400 or 0600 for permissions. Given the expectation that CAP_SYS_ADMIN is needed to access these sensitive attributes and an explicit helper with the _ADMIN_ identifier for DEVICE_ATTR_ADMIN_{RO,RW}. Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/159312906372.1850128.11611897078988158727.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-21docs: filesystems: fix renamed referencesMauro Carvalho Chehab1-1/+1
Some filesystem references got broken by a previous patch series I submitted. Address those. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Acked-by: David Sterba <dsterba@suse.com> # fs/affs/Kconfig Link: https://lore.kernel.org/r/57318c53008dbda7f6f4a5a9e5787f4d37e8565a.1586881715.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-05sysfs: remove redundant __compat_only_sysfs_link_entry_to_kobj fnLinus Torvalds1-11/+0
Commit 9255782f7061 ("sysfs: Wrap __compat_only_sysfs_link_entry_to_kobj function to change the symlink name") made this function a wrapper around a new non-underscored function, which is a bit odd. The normal naming convention is the other way around: the underscored function is the wrappee, and the non-underscored function is the wrapper. There's only one single user (well, two call-sites in that user) of the more limited double underscore version of this function, so just remove the oddly named wrapper entirely and just add the extra NULL argument to the user. I considered just doing that in the merge, but that tends to make history really hard to read. Link: https://lore.kernel.org/lkml/CAHk-=wgkkmNV5tMzQDmPAQuNJBuMcry--Jb+h8H1o4RA3kF7QQ@mail.gmail.com/ Cc: Sourabh Jain <sourabhjain@linux.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-05Merge tag 'powerpc-5.7-1' of ↵Linus Torvalds1-0/+12
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull powerpc updates from Michael Ellerman: "Slightly late as I had to rebase mid-week to insert a bug fix: - A large series from Nick for 64-bit to further rework our exception vectors, and rewrite portions of the syscall entry/exit and interrupt return in C. The result is much easier to follow code that is also faster in general. - Cleanup of our ptrace code to split various parts out that had become badly intertwined with #ifdefs over the years. - Changes to our NUMA setup under the PowerVM hypervisor which should hopefully avoid non-sensical topologies which can lead to warnings from the workqueue code and other problems. - MAINTAINERS updates to remove some of our old orphan entries and update the status of others. - Quite a few other small changes and fixes all over the map. Thanks to: Abdul Haleem, afzal mohammed, Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V, Balamuruhan S, Cédric Le Goater, Chen Zhou, Christophe JAILLET, Christophe Leroy, Christoph Hellwig, Clement Courbet, Daniel Axtens, David Gibson, Douglas Miller, Fabiano Rosas, Fangrui Song, Ganesh Goudar, Gautham R. Shenoy, Greg Kroah-Hartman, Greg Kurz, Gustavo Luiz Duarte, Hari Bathini, Ilie Halip, Jan Kara, Joe Lawrence, Joe Perches, Kajol Jain, Larry Finger, Laurentiu Tudor, Leonardo Bras, Libor Pechacek, Madhavan Srinivasan, Mahesh Salgaonkar, Masahiro Yamada, Masami Hiramatsu, Mauricio Faria de Oliveira, Michael Neuling, Michal Suchanek, Mike Rapoport, Nageswara R Sastry, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Nick Desaulniers, Oliver O'Halloran, Po-Hsu Lin, Pratik Rajesh Sampat, Rasmus Villemoes, Ravi Bangoria, Roman Bolshakov, Sam Bobroff, Sandipan Das, Santosh S, Sedat Dilek, Segher Boessenkool, Shilpasri G Bhat, Sourabh Jain, Srikar Dronamraju, Stephen Rothwell, Tyrel Datwyler, Vaibhav Jain, YueHaibing" * tag 'powerpc-5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (158 commits) powerpc: Make setjmp/longjmp signature standard powerpc/cputable: Remove unnecessary copy of cpu_spec->oprofile_type powerpc: Suppress .eh_frame generation powerpc: Drop -fno-dwarf2-cfi-asm powerpc/32: drop unused ISA_DMA_THRESHOLD powerpc/powernv: Add documentation for the opal sensor_groups sysfs interfaces selftests/powerpc: Fix try-run when source tree is not writable powerpc/vmlinux.lds: Explicitly retain .gnu.hash powerpc/ptrace: move ptrace_triggered() into hw_breakpoint.c powerpc/ptrace: create ppc_gethwdinfo() powerpc/ptrace: create ptrace_get_debugreg() powerpc/ptrace: split out ADV_DEBUG_REGS related functions. powerpc/ptrace: move register viewing functions out of ptrace.c powerpc/ptrace: split out TRANSACTIONAL_MEM related functions. powerpc/ptrace: split out SPE related functions. powerpc/ptrace: split out ALTIVEC related functions. powerpc/ptrace: split out VSX related functions. powerpc/ptrace: drop PARAMETER_SAVE_AREA_OFFSET powerpc/ptrace: drop unnecessary #ifdefs CONFIG_PPC64 powerpc/ptrace: remove unused header includes ...
2020-03-20sysfs: fix static inline declaration of sysfs_groups_change_owner()Christian Brauner1-2/+2
The CONFIG_SYSFS declaration of sysfs_group_change_owner() is different from the !CONFIG_SYSFS version and thus causes build failurs when !CONFIG_SYSFS is set. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Fixes: 303a42769c4c ("sysfs: add sysfs_group{s}_change_owner()") Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reported-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-27sysfs: add sysfs_change_owner()Christian Brauner1-0/+6
Add a helper to change the owner of sysfs objects. This function will be used to correctly account for kobject ownership changes, e.g. when moving network devices between network namespaces. This mirrors how a kobject is added through driver core which in its guts is done via kobject_add_internal() which in summary creates the main directory via create_dir(), populates that directory with the groups associated with the ktype of the kobject (if any) and populates the directory with the basic attributes associated with the ktype of the kobject (if any). These are the basic steps that are associated with adding a kobject in sysfs. Any additional properties are added by the specific subsystem itself (not by driver core) after it has registered the device. So for the example of network devices, a network device will e.g. register a queue subdirectory under the basic sysfs directory for the network device and than further subdirectories within that queues subdirectory. But that is all specific to network devices and they call the corresponding sysfs functions to do that directly when they create those queue objects. So anything that a subsystem adds outside of what driver core does must also be changed by it (That's already true for removal of files it created outside of driver core.) and it's the same for ownership changes. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-27sysfs: add sysfs_group{s}_change_owner()Christian Brauner1-0/+20
Add helpers to change the owner of sysfs groups. This function will be used to correctly account for kobject ownership changes, e.g. when moving network devices between network namespaces. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-27sysfs: add sysfs_link_change_owner()Christian Brauner1-0/+10
Add a helper to change the owner of a sysfs link. This function will be used to correctly account for kobject ownership changes, e.g. when moving network devices between network namespaces. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-27sysfs: add sysfs_file_change_owner()Christian Brauner1-0/+10
Add helpers to change the owner of a sysfs files. This function will be used to correctly account for kobject ownership changes, e.g. when moving network devices between network namespaces. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-19sysfs: Wrap __compat_only_sysfs_link_entry_to_kobj function to change the ↵Sourabh Jain1-0/+12
symlink name The __compat_only_sysfs_link_entry_to_kobj function creates a symlink to a kobject but doesn't provide an option to change the symlink file name. This patch adds a wrapper function compat_only_sysfs_link_entry_to_kobj that extends the __compat_only_sysfs_link_entry_to_kobj functionality which allows function caller to customize the symlink name. Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com> [mpe: Fix compile error when CONFIG_SYSFS=n] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20191211160910.21656-3-sourabhjain@linux.ibm.com
2019-10-02sysfs: Fixes __BIN_ATTR_WO() macroNayna Jain1-2/+2
This patch fixes the size and write parameter for the macro __BIN_ATTR_WO(). Fixes: 7f905761e15a8 ("sysfs: add BIN_ATTR_WO() macro") Signed-off-by: Nayna Jain <nayna@linux.ibm.com> Link: https://lore.kernel.org/r/1569973038-2710-1-git-send-email-nayna@linux.ibm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-09-04sysfs: add BIN_ATTR_WO() macroGreg Kroah-Hartman1-0/+9
This variant was missing from sysfs.h, I guess no one noticed it before. Turns out the powerpc secure variable code can use it, so add it to the tree for it, and potentially others to take advantage of, instead of open-coding it. Reported-by: Nayna Jain <nayna@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20190826150153.GD18418@kroah.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-03sysfs: Add sysfs_update_groups functionJiri Olsa1-0/+8
Adding sysfs_update_groups function to update multiple groups. sysfs_update_groups - given a directory kobject, create a bunch of attribute groups @kobj: The kobject to update the group on @groups: The attribute groups to update, NULL terminated This function update a bunch of attribute groups. If an error occurs when updating a group, all previously updated groups will be removed together with already existing (not updated) attributes. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190512155518.21468-2-jolsa@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-12-03sysfs: constify sysfs create/remove files harderJani Nikula1-4/+4
Let the passed in array be const (and thus placed in rodata) instead of a mutable array of const pointers. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20181004143750.30880-1-jani.nikula@intel.com
2018-08-18Merge tag 'driver-core-4.19-rc1' of ↵Linus Torvalds1-3/+3
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core updates from Greg KH: "Here are all of the driver core and related patches for 4.19-rc1. Nothing huge here, just a number of small cleanups and the ability to now stop the deferred probing after init happens. All of these have been in linux-next for a while with only a merge issue reported" * tag 'driver-core-4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (21 commits) base: core: Remove WARN_ON from link dependencies check drivers/base: stop new probing during shutdown drivers: core: Remove glue dirs from sysfs earlier driver core: remove unnecessary function extern declare sysfs.h: fix non-kernel-doc comment PM / Domains: Stop deferring probe at the end of initcall iommu: Remove IOMMU_OF_DECLARE iommu: Stop deferring probe at end of initcalls pinctrl: Support stopping deferred probe after initcalls dt-bindings: pinctrl: add a 'pinctrl-use-default' property driver core: allow stopping deferred probe after init driver core: add a debugfs entry to show deferred devices sysfs: Fix internal_create_group() for named group updates base: fix order of OF initialization linux/device.h: fix kernel-doc notation warning Documentation: update firmware loader fallback reference kobject: Replace strncpy with memcpy drivers: base: cacheinfo: use OF property_read_u32 instead of get_property,read_number kernfs: Replace strncpy with memcpy device: Add #define dev_fmt similar to #define pr_fmt ...
2018-08-02scsi: sysfs: Introduce sysfs_{un,}break_active_protection()Bart Van Assche1-0/+14
Introduce these two functions and export them such that the next patch can add calls to these functions from the SCSI core. Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: <stable@vger.kernel.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2018-07-16sysfs.h: fix non-kernel-doc commentRandy Dunlap1-3/+3
Don't use "/**" to begin this comment block since it is not a kernel-doc comment block. Also adjust comment line to fit in 80 characters. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-01-09sysfs.h: Use octal permissionsJoe Perches1-8/+6
Use the more common and preferred octal directly. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-06efi: Move some sysfs files to be read-only by rootGreg Kroah-Hartman1-0/+6
Thanks to the scripts/leaking_addresses.pl script, it was found that some EFI values should not be readable by non-root users. So make them root-only, and to do that, add a __ATTR_RO_MODE() macro to make this easier, and use it in other places at the same time. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Tested-by: Dave Young <dyoung@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Cc: stable <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20171206095010.24170-2-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-05-25sysfs: remove signedness from sysfs_get_direntNick Desaulniers1-1/+1
sysfs_get_dirent is usually invoked with a string literal, which have the type char[]. While the toplevel Makefile disables -Wpointer-sign, other Makefiles like arch/x86/boot/compressed/Makefile redefine KBUILD_CFLAGS. Fixes the warning: In file included from arch/x86/boot/compressed/kaslr.c:17: In file included from ./include/linux/module.h:17: In file included from ./include/linux/kobject.h:21: ./include/linux/sysfs.h:517:37: warning: passing 'const unsigned char *' to parameter of type 'const char *' converts between pointers to integer types with different sign [-Wpointer-sign] return kernfs_find_and_get(parent, name); ^~~~ ./include/linux/kernfs.h:462:57: note: passing argument to parameter 'name' here kernfs_find_and_get(struct kernfs_node *kn, const char *name) ^ Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-11-14Merge tag 'chrome-platform-4.4' of ↵Linus Torvalds1-4/+14
git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform Pull chrome platform updates from Olof Johansson: "Here's the branch of chrome platform changes for v4.4. Some have been queued up for the full 4.3 release cycle since I forgot to send them in for that round (rebased early on to deal with fixes conflicts). Most of these enable EC communication stuff -- Pixel 2015 support, enabling building for ARM64 platforms, and a few fixes for memory leaks. There's also a patch in here to allow reading/writing the verified boot context, which depends on a sysfs patch acked by Greg" * tag 'chrome-platform-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform: platform/chrome: Fix i2c-designware adapter name platform/chrome: Support reading/writing the vboot context sysfs: Support is_visible() on binary attributes platform/chrome: cros_ec: Fix possible leak in led_rgb_store() platform/chrome: cros_ec: Fix leak in sequence_store() platform/chrome: Enable Chrome platforms on 64-bit ARM platform/chrome: cros_ec_dev - Add a platform device ID table platform/chrome: cros_ec_lpc - Add support for Google Pixel 2 platform/chrome: cros_ec_lpc - Use existing function to check EC result platform/chrome: Make depends on MFD_CROS_EC instead CROS_EC_PROTO Revert "platform/chrome: Don't make CHROME_PLATFORMS depends on X86 || ARM"
2015-10-19sysfs: added __compat_only_sysfs_link_entry_to_kobj()Jarkko Sakkinen1-0/+11
Added a new function __compat_only_sysfs_link_group_to_kobj() that adds a symlink from attribute or group to a kobject. This needed for maintaining backwards compatibility with PPI attributes in the TPM driver. Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
2015-10-08sysfs: Support is_visible() on binary attributesEmilio López1-4/+14
According to the sysfs header file: "The returned value will replace static permissions defined in struct attribute or struct bin_attribute." but this isn't the case, as is_visible is only called on struct attribute only. This patch introduces a new is_bin_visible() function to implement the same functionality for binary attributes, and updates documentation accordingly. Note that to keep functionality and code similar to that of normal attributes, the mode is now checked as well to ensure it contains only read/write permissions or SYSFS_PREALLOC. Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Olof Johansson <olof@lixom.net>
2015-07-01sysfs: Add support for permanently empty directories to serve as mount points.Eric W. Biederman1-0/+15
Add two functions sysfs_create_mount_point and sysfs_remove_mount_point that hang a permanently empty directory off of a kobject or remove a permanently emptpy directory hanging from a kobject. Export these new functions so modular filesystems can use them. Cc: stable@vger.kernel.org Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-03-25sysfs: Document struct attribute_groupGuenter Roeck1-0/+15
Document variables defined in struct attribute_group to ensure correct usage. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-07sysfs/kernfs: allow attributes to request write buffer be pre-allocated.NeilBrown1-0/+9
md/raid allows metadata management to be performed in user-space. A various times, particularly on device failure, the metadata needs to be updated before further writes can be permitted. This means that the user-space program which updates metadata much not block on writeout, and so must not allocate memory. mlockall(MCL_CURRENT|MCL_FUTURE) and pre-allocation can avoid all memory allocation issues for user-memory, but that does not help kernel memory. Several kernel objects can be pre-allocated. e.g. files opened before any writes to the array are permitted. However some kernel allocation happens in places that cannot be pre-allocated. In particular, writes to sysfs files (to tell md that it can now allow writes to the array) allocate a buffer using GFP_KERNEL. This patch allows attributes to be marked as "PREALLOC". In that case the maximal buffer is allocated when the file is opened, and then used on each write instead of allocating a new buffer. As the same buffer is now shared for all writes on the same file description, the mutex is extended to cover full use of the buffer including the copy_from_user(). The new __ATTR_PREALLOC() 'or's a new flag in to the 'mode', which is inspected by sysfs_add_file_mode_ns() to determine if the file should be marked as requiring prealloc. Despite the comment, we *do* use ->seq_show together with ->prealloc in this patch. The next patch fixes that. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-28sysfs.h: don't return a void-valued expression in sysfs_remove_fileSimon Wunderlich1-1/+1
Sparse was complaining about that: include/linux/sysfs.h:432:9: warning: returning void-valued expression Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-16sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo1-9/+0
All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-06Merge tag 'modules-next-for-linus' of ↵Linus Torvalds1-1/+2
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module updates from Rusty Russell: "Nothing major: the stricter permissions checking for sysfs broke a staging driver; fix included. Greg KH said he'd take the patch but hadn't as the merge window opened, so it's included here to avoid breaking build" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: staging: fix up speakup kobject mode Use 'E' instead of 'X' for unsigned module taint flag. VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms. kallsyms: fix percpu vars on x86-64 with relocation. kallsyms: generalize address range checking module: LLVMLinux: Remove unused function warning from __param_check macro Fix: module signature vs tracepoints: add new TAINT_UNSIGNED_MODULE module: remove MODULE_GENERIC_TABLE module: allow multiple calls to MODULE_DEVICE_TABLE() per module module: use pr_cont
2014-03-26Revert "sysfs, driver-core: remove unused ↵Greg Kroah-Hartman1-0/+9
{sysfs|device}_schedule_callback_owner()" This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888. As reported by Stephen, this patch breaks linux-next as a ppc patch suddenly (after 2 years) started using this old api call. So revert it for now, it will go away in 3.15-rc2 when we can change the PPC call to the new api. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tejun Heo <tj@kernel.org> Cc: Stewart Smith <stewart@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-24VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms.Rusty Russell1-1/+2
Summary of http://lkml.org/lkml/2014/3/14/363 : Ted: module_param(queue_depth, int, 444) Joe: 0444! Rusty: User perms >= group perms >= other perms? Joe: CLASS_ATTR, DEVICE_ATTR, SENSOR_ATTR and SENSOR_ATTR_2? Side effect of stricter permissions means removing the unnecessary S_IFREG from several callers. Note that the BUILD_BUG_ON_ZERO((perm) & 2) test was removed: a fair number of drivers fail this test, so that will be the debate for a future patch. Suggested-by: Joe Perches <joe@perches.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> for drivers/pci/slot.c Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-02-08sysfs, kobject: add sysfs wrapper for kernfs_enable_ns()Tejun Heo1-0/+9
Currently, kobject is invoking kernfs_enable_ns() directly. This is fine now as sysfs and kernfs are enabled and disabled together. If sysfs is disabled, kernfs_enable_ns() is switched to dummy implementation too and everything is fine; however, kernfs will soon have its own config option CONFIG_KERNFS and !SYSFS && KERNFS will be possible, which can make kobject call into non-dummy kernfs_enable_ns() with NULL kernfs_node pointers leading to an oops. Introduce sysfs_enable_ns() which is a wrapper around kernfs_enable_ns() so that it can be made a noop depending only on CONFIG_SYSFS regardless of the planned CONFIG_KERNFS. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-08sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo1-9/+0
All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-08kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappersTejun Heo1-0/+7
Sometimes it's necessary to implement a node which wants to delete nodes including itself. This isn't straightforward because of kernfs active reference. While a file operation is in progress, an active reference is held and kernfs_remove() waits for all such references to drain before completing. For a self-deleting node, this is a deadlock as kernfs_remove() ends up waiting for an active reference that itself is sitting on top of. This currently is worked around in the sysfs layer using sysfs_schedule_callback() which makes such removals asynchronous. While it works, it's rather cumbersome and inherently breaks synchronicity of the operation - the file operation which triggered the operation may complete before the removal is finished (or even started) and the removal may fail asynchronously. If a removal operation is immmediately followed by another operation which expects the specific name to be available (e.g. removal followed by rename onto the same name), there's no way to make the latter operation reliable. The thing is there's no inherent reason for this to be asynchrnous. All that's necessary to do this synchronous is a dedicated operation which drops its own active ref and deactivates self. This patch implements kernfs_remove_self() and its wrappers in sysfs and driver core. kernfs_remove_self() is to be called from one of the file operations, drops the active ref the task is holding, removes the self node, and restores active ref to the dead node so that the ref is balanced afterwards. __kernfs_remove() is updated so that it takes an early exit if the target node is already fully removed so that the active ref restored by kernfs_remove_self() after removal doesn't confuse the deactivation path. This makes implementing self-deleting nodes very easy. The normal removal path doesn't even need to be changed to use kernfs_remove_self() for the self-deleting node. The method can invoke kernfs_remove_self() on itself before proceeding the normal removal path. kernfs_remove() invoked on the node by the normal deletion path will simply be ignored. This will replace sysfs_schedule_callback(). A subtle feature of sysfs_schedule_callback() is that it collapses multiple invocations - even if multiple removals are triggered, the removal callback is run only once. An equivalent effect can be achieved by testing the return value of kernfs_remove_self() - only the one which gets %true return value should proceed with actual deletion. All other instances of kernfs_remove_self() will wait till the enclosing kernfs operation which invoked the winning instance of kernfs_remove_self() finishes and then return %false. This trivially makes all users of kernfs_remove_self() automatically show correct synchronous behavior even when there are multiple concurrent operations - all "echo 1 > delete" instances will finish only after the whole operation is completed by one of the instances. Note that manipulation of active ref is implemented in separate public functions - kernfs_[un]break_active_protection(). kernfs_remove_self() is the only user at the moment but this will be used to cater to more complex cases. v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing and sysfs_remove_file_self() had incorrect return type. Fix it. Reported by kbuild test bot. v3: kernfs_[un]break_active_protection() separated out from kernfs_remove_self() and exposed as public API. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-14Revert "kernfs, sysfs, driver-core: implement kernfs_remove_self() and its ↵Greg Kroah-Hartman1-7/+0
wrappers" This reverts commit 1ae06819c77cff1ea2833c94f8c093fe8a5c79db. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-14Revert "sysfs, driver-core: remove unused ↵Greg Kroah-Hartman1-0/+9
{sysfs|device}_schedule_callback_owner()" This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-11sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo1-9/+0
All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>