kernel/linux.git/drivers/base/core.c, branch v4.17.1

driver core: Introduce device links reference counting

2018-02-27T17:10:42+00:00

If device_link_add() is invoked multiple times with the same supplier and consumer combo, it will create the link on first addition and return a pointer to the already existing link on all subsequent additions. The semantics for device_link_del() are quite different, it deletes the link unconditionally, so multiple invocations are not allowed. In other words, this snippet ... struct device *dev1, *dev2; struct device_link *link1, *link2; link1 = device_link_add(dev1, dev2, 0); link2 = device_link_add(dev1, dev2, 0); device_link_del(link1); device_link_del(link2); ... causes the following crash: WARNING: CPU: 4 PID: 2686 at drivers/base/power/runtime.c:1611 pm_runtime_drop_link+0x40/0x50 [...] list_del corruption, 0000000039b800a4->prev is LIST_POISON2 (00000000ecf79852) kernel BUG at lib/list_debug.c:50! The issue isn't as arbitrary as it may seem: Imagine a device link which is added in both the supplier's and the consumer's ->probe hook. The two drivers can't just call device_link_del() in their ->remove hook without coordination. Fix by counting multiple additions and dropping the device link only when the last addition is unwound. Signed-off-by: Lukas Wunner [ rjw: Subject ] Signed-off-by: Rafael J. Wysocki

PM / runtime: Update links_count also if !CONFIG_SRCU

2018-02-12T10:12:58+00:00

Commit baa8809f6097 (PM / runtime: Optimize the use of device links) added an invocation of pm_runtime_drop_link() to __device_link_del(). However there are two variants of that function, one for CONFIG_SRCU and another for !CONFIG_SRCU, and the commit only modified the former. Fixes: baa8809f6097 (PM / runtime: Optimize the use of device links) Cc: v4.10+ # v4.10+ Signed-off-by: Lukas Wunner Signed-off-by: Rafael J. Wysocki

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk

2018-02-01T21:36:15+00:00

Pull printk updates from Petr Mladek: - Add a console_msg_format command line option: The value "default" keeps the old "[time stamp] text\n" format. The value "syslog" allows to see the syslog-like "[timestamp] text" format. This feature was requested by people doing regression tests, for example, 0day robot. They want to have both filtered and full logs at hands. - Reduce the risk of softlockup: Pass the console owner in a busy loop. This is a new approach to the old problem. It was first proposed by Steven Rostedt on Kernel Summit 2017. It marks a context in which the console_lock owner calls console drivers and could not sleep. On the other side, printk() callers could detect this state and use a busy wait instead of a simple console_trylock(). Finally, the console_lock owner checks if there is a busy waiter at the end of the special context and eventually passes the console_lock to the waiter. The hand-off works surprisingly well and helps in many situations. Well, there is still a possibility of the softlockup, for example, when the flood of messages stops and the last owner still has too much to flush. There is increasing number of people having problems with printk-related softlockups. We might eventually need to get better solution. Anyway, this looks like a good start and promising direction. - Do not allow to schedule in console_unlock() called from printk(): This reverts an older controversial commit. The reschedule helped to avoid softlockups. But it also slowed down the console output. This patch is obsoleted by the new console waiter logic described above. In fact, the reschedule made the hand-off less effective. - Deprecate "%pf" and "%pF" format specifier: It was needed on ia64, ppc64 and parisc64 to dereference function descriptors and show the real function address. It is done transparently by "%ps" and "pS" format specifier now. Sergey Senozhatsky found that all the function descriptors were in a special elf section and could be easily detected. - Remove printk_symbol() API: It has been obsoleted by "%pS" format specifier, and this change helped to remove few continuous lines and a less intuitive old API. - Remove redundant memsets: Sergey removed unnecessary memset when processing printk.devkmsg command line option. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: (27 commits) printk: drop redundant devkmsg_log_str memsets printk: Never set console_may_schedule in console_trylock() printk: Hide console waiter logic into helpers printk: Add console owner and waiter logic to load balance console writes kallsyms: remove print_symbol() function checkpatch: add pF/pf deprecation warning symbol lookup: introduce dereference_symbol_descriptor() parisc64: Add .opd based function descriptor dereference powerpc64: Add .opd based function descriptor dereference ia64: Add .opd based function descriptor dereference sections: split dereference_function_descriptor() openrisc: Fix conflicting types for _exext and _stext lib: do not use print_symbol() irq debug: do not use print_symbol() sysfs: do not use print_symbol() drivers: do not use print_symbol() x86: do not use print_symbol() unicore32: do not use print_symbol() sh: do not use print_symbol() mn10300: do not use print_symbol() ...

drivers: do not use print_symbol()

2018-01-05T14:23:59+00:00

print_symbol() is a very old API that has been obsoleted by %pS format specifier in a normal printk() call. Replace print_symbol() with a direct printk("%pS") call. Link: http://lkml.kernel.org/r/20171211125025.2270-10-sergey.senozhatsky@gmail.com To: Andrew Morton To: Russell King To: Catalin Marinas To: Mark Salter To: Tony Luck To: David Howells To: Yoshinori Sato To: Guan Xuetao To: Borislav Petkov To: Greg Kroah-Hartman To: Thomas Gleixner To: Peter Zijlstra To: Vineet Gupta To: Fengguang Wu Cc: Steven Rostedt Cc: Petr Mladek Cc: LKML Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-ia64@vger.kernel.org Cc: linux-am33-list@redhat.com Cc: linux-sh@vger.kernel.org Cc: linux-edac@vger.kernel.org Cc: x86@kernel.org Cc: linux-snps-arc@lists.infradead.org Signed-off-by: Sergey Senozhatsky [pmladek@suse.com: updated commit message] Signed-off-by: Petr Mladek

drivers: base: omit redundant interations

2017-12-18T15:47:27+00:00

When error happens, these interators return the error, no interation should be continued, so make the change for getting out of while immediately. Signed-off-by: Gimcuan Hui Signed-off-by: Greg Kroah-Hartman

driver core: Remove redundant license text

2017-12-07T17:36:44+00:00

Now that the SPDX tag is in all driver core files, that identifies the license in a specific and legally-defined manner. So the extra GPL text wording can be removed as it is no longer needed at all. This is done on a quest to remove the 700+ different ways that files in the kernel describe the GPL license text. And there's unneeded stuff like the address (sometimes incorrect) for the FSF which is never needed. No copyright headers or other non-license-description text was removed. Cc: Johannes Berg Cc: "Luis R. Rodriguez" Signed-off-by: Greg Kroah-Hartman

driver core: add SPDX identifiers to all driver core files

2017-12-07T17:36:43+00:00

It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the driver core files files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Johannes Berg Cc: "Luis R. Rodriguez" Cc: William Breathitt Gray Cc: Thomas Gleixner Cc: Kate Stewart Cc: Philippe Ombredanne Signed-off-by: Greg Kroah-Hartman

Merge tag 'driver-core-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2017-11-16T16:55:30+00:00

Pull driver core updates from Greg KH: "Here is the set of driver core / debugfs patches for 4.15-rc1. Not many here, mostly all are debugfs fixes to resolve some long-reported problems with files going away with references to them in userspace. There's also some SPDX cleanups for the debugfs code, as well as a few other minor driver core changes for issues reported by people. All of these have been in linux-next for a week or more with no reported issues" * tag 'driver-core-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: driver core: Fix device link deferred probe debugfs: Remove redundant license text debugfs: add SPDX identifiers to all debugfs files debugfs: defer debugfs_fsdata allocation to first usage debugfs: call debugfs_real_fops() only after debugfs_file_get() debugfs: purge obsolete SRCU based removal protection IB/hfi1: convert to debugfs_file_get() and -put() debugfs: convert to debugfs_file_get() and -put() debugfs: debugfs_real_fops(): drop __must_hold sparse annotation debugfs: implement per-file removal protection debugfs: add support for more elaborate ->d_fsdata driver core: Move device_links_purge() after bus_remove_device() arch_topology: Fix section miss match warning due to free_raw_capacity() driver-core: pr_err() strings should end with newlines

Merge tag 'devicetree-for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux

2017-11-15T02:25:40+00:00

Pull DeviceTree updates from Rob Herring: "A bigger diffstat than usual with the kbuild changes and a tree wide fix in the binding documentation. Summary: - kbuild cleanups and improvements for dtbs - Code clean-up of overlay code and fixing for some long standing memory leak and race condition in applying overlays - Improvements to DT memory usage making sysfs/kobjects optional and skipping unflattening of disabled nodes. This is part of kernel tinification efforts. - Final piece of removing storing the full path for every DT node. The prerequisite conversion of printk's to use device_node format specifier happened in 4.14. - Sync with current upstream dtc. This brings additional checks to dtb compiling. - Binding doc tree wide removal of leading 0s from examples - RTC binding documentation adding missing devices and some consolidation of duplicated bindings - Vendor prefix documentation for nutsboard, Silicon Storage Technology, shimafuji, Tecon Microprocessor Technologies, DH electronics GmbH, Opal Kelly, and Next Thing" * tag 'devicetree-for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (55 commits) dt-bindings: usb: add #phy-cells to usb-nop-xceiv dt-bindings: Remove leading zeros from bindings notation kbuild: handle dtb-y and CONFIG_OF_ALL_DTBS natively in Makefile.lib MIPS: dts: remove bogus bcm96358nb4ser.dtb from dtb-y entry kbuild: clean up *.dtb and *.dtb.S patterns from top-level Makefile .gitignore: move *.dtb and *.dtb.S patterns to the top-level .gitignore .gitignore: sort normal pattern rules alphabetically dt-bindings: add vendor prefix for Next Thing Co. scripts/dtc: Update to upstream version v1.4.5-6-gc1e55a5513e9 of: dynamic: fix memory leak related to properties of __of_node_dup of: overlay: make pr_err() string unique of: overlay: pr_err from return NOTIFY_OK to overlay apply/remove of: overlay: remove unneeded check for NULL kbasename() of: overlay: remove a dependency on device node full_name of: overlay: simplify applying symbols from an overlay of: overlay: avoid race condition between applying multiple overlays of: overlay: loosen overly strict phandle clash check of: overlay: expand check of whether overlay changeset can be removed of: overlay: detect cases where device tree may become corrupt of: overlay: minor restructuring ...

locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

2017-10-25T09:01:08+00:00

Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland Signed-off-by: Paul E. McKenney Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar