kernel/linux.git/drivers/pci/hotplug/pnv_php.c, branch v4.19.77

PCI: hotplug: Demidlayer registration with the core

2018-07-23T22:04:13+00:00

When a hotplug driver calls pci_hp_register(), all steps necessary for registration are carried out in one go, including creation of a kobject and addition to sysfs. That's a problem for pciehp once it's converted to enable/disable the slot exclusively from the IRQ thread: The thread needs to be spawned after creation of the kobject (because it uses the kobject's name), but before addition to sysfs (because it will handle enable/disable requests submitted via sysfs). pci_hp_deregister() does offer a ->release callback that's invoked after deletion from sysfs and before destruction of the kobject. But because pci_hp_register() doesn't offer a counterpart, hotplug drivers' ->probe and ->remove code becomes asymmetric, which is error prone as recently discovered use-after-free bugs in pciehp's ->remove hook have shown. In a sense, this appears to be a case of the midlayer antipattern: "The core thesis of the "midlayer mistake" is that midlayers are bad and should not exist. That common functionality which it is so tempting to put in a midlayer should instead be provided as library routines which can [be] used, augmented, or ignored by each bottom level driver independently. Thus every subsystem that supports multiple implementations (or drivers) should provide a very thin top layer which calls directly into the bottom layer drivers, and a rich library of support code that eases the implementation of those drivers. This library is available to, but not forced upon, those drivers." -- Neil Brown (2009), https://lwn.net/Articles/336262/ The presence of midlayer traits in the PCI hotplug core might be ascribed to its age: When it was introduced in February 2002, the blessings of a library approach might not have been well known: https://git.kernel.org/tglx/history/c/a8a2069f432c For comparison, the driver core does offer split functions for creating a kobject (device_initialize()) and addition to sysfs (device_add()) as an alternative to carrying out everything at once (device_register()). This was introduced in October 2002: https://git.kernel.org/tglx/history/c/8b290eb19962 The odd ->release callback in the PCI hotplug core was added in 2003: https://git.kernel.org/tglx/history/c/69f8d663b595 Clearly, a library approach would not force every hotplug driver to implement a ->release callback, but rather allow the driver to remove the sysfs files, release its data structures and finally destroy the kobject. Alternatively, a driver may choose to remove everything with pci_hp_deregister(), then release its data structures. To this end, offer drivers pci_hp_initialize() and pci_hp_add() as a split-up version of pci_hp_register(). Likewise, offer pci_hp_del() and pci_hp_destroy() as a split-up version of pci_hp_deregister(). Eliminate the ->release callback and move its code into each driver's teardown routine. Declare pci_hp_deregister() void, in keeping with the usual kernel pattern that enablement can fail, but disablement cannot. It only returned an error if the caller passed in a NULL pointer or a slot which has never or is no longer registered or is sharing its name with another slot. Those would be bugs, so WARN about them. Few hotplug drivers actually checked the return value and those that did only printed a useless error message to dmesg. Remove that. For most drivers the conversion was straightforward since it doesn't matter whether the code in the ->release callback is executed before or after destruction of the kobject. But in the case of ibmphp, it was unclear to me whether setting slot_cur->ctrl and slot_cur->bus_on to NULL needs to happen before the kobject is destroyed, so I erred on the side of caution and ensured that the order stays the same. Another nontrivial case is pnv_php, I've found the list and kref logic difficult to understand, however my impression was that it is safe to delete the list element and drop the references until after the kobject is destroyed. Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Acked-by: Andy Shevchenko # drivers/platform/x86 Cc: Rafael J. Wysocki Cc: Len Brown Cc: Scott Murray Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Gavin Shan Cc: Sebastian Ott Cc: Gerald Schaefer Cc: Corentin Chary Cc: Darren Hart Cc: Andy Shevchenko

PCI: pnv_php: Add missing of_node_put()

2018-05-23T21:48:37+00:00

The device node iterators perform an of_node_get() on each iteration, so a jump out of the loop requires an of_node_put(). The semantic patch that fixes this problem is as follows (http://coccinelle.lip6.fr): // @@ expression root,e; local idexpression child; iterator name for_each_child_of_node; @@ for_each_child_of_node(root, child) { ... when != of_node_put(child) when != e = child + of_node_put(child); ? break; ... } ... when != child // Signed-off-by: Julia Lawall Signed-off-by: Bjorn Helgaas

PCI/hotplug: ppc: correct a php_slot usage after free

2018-03-13T04:50:32+00:00

In pnv_php_unregister_one(), pnv_php_put_slot() might kfree php_slot structure. But there is pci_hp_deregister() after that with php_slot reference. This patch moves pnv_php_put_slot() to the end of function. Signed-off-by: Simon Guo Signed-off-by: Michael Ellerman

Merge branch 'pci/spdx' into next

2018-02-01T17:40:07+00:00

* pci/spdx: PCI: Add SPDX GPL-2.0+ to replace implicit GPL v2 or later statement PCI: Add SPDX GPL-2.0+ to replace GPL v2 or later boilerplate PCI: Add SPDX GPL-2.0 to replace COPYING boilerplate PCI: Add SPDX GPL-2.0 to replace GPL v2 boilerplate PCI: Add SPDX GPL-2.0 when no license was specified

PCI: Add SPDX GPL-2.0+ to replace GPL v2 or later boilerplate

2018-01-28T21:49:06+00:00

Add SPDX GPL-2.0+ to all PCI files that specified the GPL and allowed either GPL version 2 or any later version. Remove the boilerplate GPL version 2 or later language, relying on the assertion in b24413180f56 ("License cleanup: add SPDX GPL-2.0 license identifier to files with no license") that the SPDX identifier may be used instead of the full boilerplate text. Signed-off-by: Bjorn Helgaas Reviewed-by: Greg Kroah-Hartman

PCI: Add wrappers for dev_printk()

2018-01-18T18:55:24+00:00

Add PCI-specific dev_printk() wrappers and use them to simplify the code slightly. No functional change intended. Signed-off-by: Frederick Lawler [bhelgaas: squash into one patch] Signed-off-by: Bjorn Helgaas

PCI: Remove unnecessary messages for memory allocation failures

2018-01-17T14:41:41+00:00

Per ebfdc40969f2 ("checkpatch: attempt to find unnecessary 'out of memory' messages"), when a memory allocation fails, the memory subsystem emits generic "out of memory" messages (see slab_out_of_memory() for some of this logging). Therefore, additional error messages in the caller don't add much value. Remove messages that merely report "out of memory". This preserves some messages that report additional information, e.g., allocation failures that mean we drop hotplug events. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring [bhelgaas: changelog, squash patches, make similar changes to acpiphp, cpqphp, ibmphp, keep warning when dropping hotplug event] Signed-off-by: Bjorn Helgaas

PCI: Convert to using %pOF instead of full_name()

2017-08-24T16:24:59+00:00

Now that we have a custom printf format specifier, convert users of full_name() to use %pOF instead. This is preparation for removing storing of the full path string for each node. Signed-off-by: Rob Herring Signed-off-by: Bjorn Helgaas Reviewed-by: Tyrel Datwyler Cc: Thomas Petazzoni Cc: Jason Cooper Cc: Thierry Reding Cc: Jonathan Hunter Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman

Merge tag 'powerpc-4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2017-03-01T18:10:16+00:00

Pull more powerpc updates from Michael Ellerman: "Highlights include: - an update of the disassembly code used by xmon to the latest versions in binutils. We've received permission from all the authors of the relevant binutils changes to relicense their changes to the relevant files from GPLv3 to GPLv2, for inclusion in Linux. Thanks to Peter Bergner for doing the leg work to get permission from everyone. - addition of the "architected" Power9 CPU table entry, allowing us to boot in Power9 architected mode under a hypervisor. - updates to the Power9 PMU code. - implementation of clear_bit_unlock_is_negative_byte() to optimise unlock_page(). - Freescale updates from Scott: "Highlights include 8xx breakpoints and perf, t1042rdb display support, and board updates." Thanks to: Al Viro, Andrew Donnellan, Aneesh Kumar K.V, Balbir Singh, Douglas Miller, Frédéric Weisbecker, Gavin Shan, Madhavan Srinivasan, Michael Roth, Nathan Fontenot, Naveen N. Rao, Nicholas Piggin, Peter Bergner, Paul E. McKenney, Rashmica Gupta, Russell Currey, Sahil Mehta, Stewart Smith" * tag 'powerpc-4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (48 commits) powerpc: Remove leftover cputime_to_nsecs call causing build error powerpc/mm/hash: Always clear UPRT and Host Radix bits when setting up CPU powerpc/optprobes: Fix TOC handling in optprobes trampoline powerpc/pseries: Advertise Hot Plug Event support to firmware cxl: fix nested locking hang during EEH hotplug powerpc/xmon: Dump memory in CPU endian format powerpc/pseries: Revert 'Auto-online hotplugged memory' powerpc/powernv: Make PCI non-optional powerpc/64: Implement clear_bit_unlock_is_negative_byte() powerpc/powernv: Remove unused variable in pnv_pci_sriov_disable() powerpc/kernel: Remove error message in pcibios_setup_phb_resources() powerpc/mm: Fix typo in set_pte_at() pci/hotplug/pnv-php: Disable MSI and PCI device properly pci/hotplug/pnv-php: Disable surprise hotplug capability on conflicts pci/hotplug/pnv-php: Remove WARN_ON() in pnv_php_put_slot() powerpc: Add POWER9 architected mode to cputable powerpc/perf: use is_kernel_addr macro in perf_get_misc_flags() powerpc/perf: Avoid FAB_*_MATCH checks for power9 powerpc/perf: Add restrictions to PMC5 in power9 DD1 powerpc/perf: Use Instruction Counter value ...

pci/hotplug/pnv-php: Disable MSI and PCI device properly

2017-02-17T11:13:29+00:00

pnv_php_disable_irq() can be called in two paths: Bailing path in pnv_php_enable_irq() or releasing slot. The MSI (or MSIx) interrupts is disabled unconditionally in pnv_php_disable_irq(). It's wrong because that might be enabled by drivers other than pnv-php. This disables MSI (or MSIx) interrupts and the PCI device only if it was enabled by pnv-php. In the error path of pnv_php_enable_irq(), we rely on the newly added parameter @disable_device. In the path of releasing slot, @pnv_php->irq is checked. Cc: # v4.9+ Fixes: 360aebd85a4c ("drivers/pci/hotplug: Support surprise hotplug in powernv driver") Signed-off-by: Gavin Shan Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman