kernel/linux.git/drivers/base/power/runtime.c, branch v6.19.11

PM: runtime: Fix a race condition related to device removal

2026-03-25T10:13:26+00:00

[ Upstream commit 29ab768277617452d88c0607c9299cdc63b6e9ff ] The following code in pm_runtime_work() may dereference the dev->parent pointer after the parent device has been freed: /* Maybe the parent is now able to suspend. */ if (parent && !parent->power.ignore_children) { spin_unlock(&dev->power.lock); spin_lock(&parent->power.lock); rpm_idle(parent, RPM_ASYNC); spin_unlock(&parent->power.lock); spin_lock(&dev->power.lock); } Fix this by inserting a flush_work() call in pm_runtime_remove(). Without this patch blktest block/001 triggers the following complaint sporadically: BUG: KASAN: slab-use-after-free in lock_acquire+0x70/0x160 Read of size 1 at addr ffff88812bef7198 by task kworker/u553:1/3081 Workqueue: pm pm_runtime_work Call Trace: dump_stack_lvl+0x61/0x80 print_address_description.constprop.0+0x8b/0x310 print_report+0xfd/0x1d7 kasan_report+0xd8/0x1d0 __kasan_check_byte+0x42/0x60 lock_acquire.part.0+0x38/0x230 lock_acquire+0x70/0x160 _raw_spin_lock+0x36/0x50 rpm_suspend+0xc6a/0xfe0 rpm_idle+0x578/0x770 pm_runtime_work+0xee/0x120 process_one_work+0xde3/0x1410 worker_thread+0x5eb/0xfe0 kthread+0x37b/0x480 ret_from_fork+0x6cb/0x920 ret_from_fork_asm+0x11/0x20 Allocated by task 4314: kasan_save_stack+0x2a/0x50 kasan_save_track+0x18/0x40 kasan_save_alloc_info+0x3d/0x50 __kasan_kmalloc+0xa0/0xb0 __kmalloc_noprof+0x311/0x990 scsi_alloc_target+0x122/0xb60 [scsi_mod] __scsi_scan_target+0x101/0x460 [scsi_mod] scsi_scan_channel+0x179/0x1c0 [scsi_mod] scsi_scan_host_selected+0x259/0x2d0 [scsi_mod] store_scan+0x2d2/0x390 [scsi_mod] dev_attr_store+0x43/0x80 sysfs_kf_write+0xde/0x140 kernfs_fop_write_iter+0x3ef/0x670 vfs_write+0x506/0x1470 ksys_write+0xfd/0x230 __x64_sys_write+0x76/0xc0 x64_sys_call+0x213/0x1810 do_syscall_64+0xee/0xfc0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Freed by task 4314: kasan_save_stack+0x2a/0x50 kasan_save_track+0x18/0x40 kasan_save_free_info+0x3f/0x50 __kasan_slab_free+0x67/0x80 kfree+0x225/0x6c0 scsi_target_dev_release+0x3d/0x60 [scsi_mod] device_release+0xa3/0x220 kobject_cleanup+0x105/0x3a0 kobject_put+0x72/0xd0 put_device+0x17/0x20 scsi_device_dev_release+0xacf/0x12c0 [scsi_mod] device_release+0xa3/0x220 kobject_cleanup+0x105/0x3a0 kobject_put+0x72/0xd0 put_device+0x17/0x20 scsi_device_put+0x7f/0xc0 [scsi_mod] sdev_store_delete+0xa5/0x120 [scsi_mod] dev_attr_store+0x43/0x80 sysfs_kf_write+0xde/0x140 kernfs_fop_write_iter+0x3ef/0x670 vfs_write+0x506/0x1470 ksys_write+0xfd/0x230 __x64_sys_write+0x76/0xc0 x64_sys_call+0x213/0x1810 Reported-by: Ming Lei Closes: https://lore.kernel.org/all/ZxdNvLNI8QaOfD2d@fedora/ Reported-by: syzbot+6c905ab800f20cf4086c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68c13942.050a0220.2ff435.000b.GAE@google.com/ Fixes: 5e928f77a09a ("PM: Introduce core framework for run-time PM of I/O devices (rev. 17)") Signed-off-by: Bart Van Assche Link: https://patch.msgid.link/20260312182720.2776083-1-bvanassche@acm.org Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

PM: runtime: Do not clear needs_force_resume with enabled runtime PM

2025-12-16T11:58:57+00:00

Commit 89d9cec3b1e9 ("PM: runtime: Clear power.needs_force_resume in pm_runtime_reinit()") added provisional clearing of power.needs_force_resume to pm_runtime_reinit(), but it is done unconditionally which is a mistake because pm_runtime_reinit() may race with driver probing and removal [1]. To address this, notice that power.needs_force_resume should never be set when runtime PM is enabled and so it only needs to be cleared when runtime PM is disabled, and update pm_runtime_init() to only clear that flag when runtime PM is disabled. Fixes: 89d9cec3b1e9 ("PM: runtime: Clear power.needs_force_resume in pm_runtime_reinit()") Reported-by: Ed Tsai Closes: https://lore.kernel.org/linux-pm/20251215122154.3180001-1-ed.tsai@mediatek.com/ [1] Signed-off-by: Rafael J. Wysocki Cc: 6.17+ # 6.17+ Reviewed-by: Ulf Hansson Link: https://patch.msgid.link/12807571.O9o76ZdvQC@rafael.j.wysocki

PM: runtime: Make pm_runtime_barrier() return void

2025-12-04T19:38:13+00:00

No callers check the return code, and that's a good thing. Doing so would be racy and unhelpful. Drop the return code entirely, so we don't make anyone think about its complexities. Signed-off-by: Brian Norris Tested-by: Guenter Roeck Link: https://patch.msgid.link/20251202193129.1411419-2-briannorris@chromium.org Signed-off-by: Rafael J. Wysocki

PM: runtime: fix typos in runtime.c comments

2025-10-29T18:58:58+00:00

Fix several typos in comments: - "timesptamp" -> "timestamp" - "involed" -> "involved" - "nonero" -> "nonzero" Fix typos in comments to improve code documentation clarity. Signed-off-by: Malaya Kumar Rout Link: https://patch.msgid.link/20251026170527.262003-1-mrout@redhat.com Signed-off-by: Rafael J. Wysocki

PM: runtime: docs: Update pm_runtime_allow/forbid() documentation

2025-10-23T14:13:33+00:00

Drop confusing descriptions of pm_runtime_allow() and pm_runtime_forbid() from Documentation/power/runtime_pm.rst and update the kerneldoc comments of these functions to better explain their purpose. Link: https://lore.kernel.org/linux-pm/08976178-298f-79d9-1d63-cff5a4e56cc3@linux.intel.com/ Signed-off-by: Rafael J. Wysocki Reviewed-by: Brian Norris Reviewed-by: Ulf Hansson Reviewed-by: Ilpo Järvinen Link: https://patch.msgid.link/12780841.O9o76ZdvQC@rafael.j.wysocki

Merge branches 'pm-core' and 'pm-runtime'

2025-10-07T10:20:36+00:00

Merge runtime PM framework updates and a core power management code fix for 6.18-rc1: - Make pm_runtime_put*() family of functions return 1 when the given device is already suspended which is consistent with the documentation (Brian Norris) - Add basic kunit tests for runtime PM API contracts and update return values in kerneldoc coments for the runtime PM API (Brian Norris, Dan Carpenter) - Add auto-cleanup macros for runtime PM "resume and get" and "get without resume" operations, use one of them in the PCI core and drop the existing "free" macro introduced for similar purpose, but somewhat cumbersome to use (Rafael Wysocki) - Make the core power management code avoid waiting on device links marked as SYNC_STATE_ONLY which is consistent with the handling of those device links elsewhere (Pin-yen Lin) * pm-core: PM: sleep: Do not wait on SYNC_STATE_ONLY device links * pm-runtime: PM: runtime: Fix error checking for kunit_device_register() PM: runtime: Introduce one more usage counter guard PM: runtime: Drop DEFINE_FREE() for pm_runtime_put() PCI/sysfs: Use runtime PM guard macro for auto-cleanup PM: runtime: Add auto-cleanup macros for "resume and get" operations PM: runtime: Update kerneldoc return codes PM: runtime: Make put{,_sync}() return 1 when already suspended PM: runtime: Add basic kunit tests for API contracts

PM: runtime: Add auto-cleanup macros for "resume and get" operations

2025-09-29T15:00:21+00:00

It is generally useful to be able to automatically drop a device's runtime PM usage counter incremented by runtime PM operations that resume a device and bump up its usage counter [1]. To that end, add guard definition macros allowing pm_runtime_put() and pm_runtime_put_autosuspend() to be used for the auto-cleanup in those cases. Simply put, a piece of code like below: pm_runtime_get_sync(dev); ..... pm_runtime_put(dev); return 0; can be transformed with guard() like: guard(pm_runtime_active)(dev); ..... return 0; (see the pm_runtime_put() call is gone). However, it is better to do proper error handling in the majority of cases, so doing something like this instead of the above is recommended: ACQUIRE(pm_runtime_active_try, pm)(dev); if (ACQUIRE_ERR(pm_runtime_active_try, &pm)) return -ENXIO; ..... return 0; In all of the cases in which runtime PM is known to be enabled for the given device or the device can be regarded as operational (and so it can be accessed) with runtime PM disabled, a piece of code like: ret = pm_runtime_resume_and_get(dev); if (ret < 0) return ret; ..... pm_runtime_put(dev); return 0; can be changed as follows: ACQUIRE(pm_runtime_active_try, pm)(dev); ret = ACQUIRE_ERR(pm_runtime_active_try, &pm); if (ret < 0) return ret; ..... return 0; (again, see the pm_runtime_put() call is gone). Still, if the device cannot be accessed unless runtime PM has been enabled for it, the pm_runtime_active_try_enabled guard variant needs to be used, that is (in the context of the example above): ACQUIRE(pm_runtime_active_try_enabled, pm)(dev); ret = ACQUIRE_ERR(pm_runtime_active_try_enabled, &pm); if (ret < 0) return ret; ..... return 0; When the original code calls pm_runtime_put_autosuspend(), use one of the "auto" guard variants, pm_runtime_active_auto/_try/_enabled, so for example, a piece of code like: ret = pm_runtime_resume_and_get(dev); if (ret < 0) return ret; ..... pm_runtime_put_autosuspend(dev); return 0; will become: ACQUIRE(pm_runtime_active_auto_try_enabled, pm)(dev); ret = ACQUIRE_ERR(pm_runtime_active_auto_try_enabled, &pm); if (ret < 0) return ret; ..... return 0; Note that the cases in which the return value of pm_runtime_get_sync() is checked can also be handled with the help of the new guard macros. For example, a piece of code like: ret = pm_runtime_get_sync(dev); if (ret < 0) { pm_runtime_put(dev); return ret; } ..... pm_runtime_put(dev); return 0; can be rewritten as: ACQUIRE(pm_runtime_active_auto_try_enabled, pm)(dev); ret = ACQUIRE_ERR(pm_runtime_active_auto_try_enabled, &pm); if (ret < 0) return ret; ..... return 0; or pm_runtime_get_active_try can be used if transparent handling of disabled runtime PM is desirable. Link: https://lore.kernel.org/linux-pm/878qimv24u.wl-tiwai@suse.de/ [1] Link: https://lore.kernel.org/linux-pm/20250926150613.000073a4@huawei.com/ Signed-off-by: Rafael J. Wysocki Acked-by: Dan Williams Reviewed-by: Takashi Iwai Link: https://patch.msgid.link/2238241.irdbgypaU6@rafael.j.wysocki [ rjw: Fixed leftovers from the previous version in the changelog ] Reviewed-by: Jonathan Cameron Reviewed-by: Dhruva Gole Signed-off-by: Rafael J. Wysocki

PM: runtime: Make put{,_sync}() return 1 when already suspended

2025-09-27T11:41:47+00:00

The pm_runtime.h docs say pm_runtime_put() and pm_runtime_put_sync() return 1 when already suspended, but this is not true -- they return -EAGAIN. On the other hand, pm_runtime_put_sync_suspend() and pm_runtime_put_sync_autosuspend() *do* return 1. This is an artifact of the fact that the former are built on rpm_idle(), whereas the latter are built on rpm_suspend(). There are precious few pm_runtime_put()/pm_runtime_put_sync() callers that check the return code at all, but most of them only log errors, and usually only for negative error codes. None of them should be treating this as an error, so: * at best, this may fix some case where a driver treats this condition as an error, when it shouldn't; * at worst, this should make no effect; and * somewhere in between, we could potentially clear up non-fatal log messages. Fix the pm_runtime_already_suspended_test() while tweaking the behavior. The test makes a lot more sense when these all return 1 when the device is already suspended: pm_runtime_put_sync(dev); pm_runtime_suspend(dev); pm_runtime_autosuspend(dev); pm_request_autosuspend(dev); pm_runtime_put_sync_autosuspend(dev); Notably, I've avoided testing the return codes for these, since they really should be ignored by callers, and we may make them 'void' altogether: pm_runtime_put(dev); pm_runtime_put_autosuspend(dev); Signed-off-by: Brian Norris Reviewed-by: Dhruva Gole Reviewed-by: Sakari Ailus Signed-off-by: Rafael J. Wysocki

PM: core: Add two macros for walking device links

2025-09-06T15:16:32+00:00

Add separate macros for walking links to suppliers and consumers of a device to help device links users to avoid exposing the internals of struct dev_links_info in their code and possible coding mistakes related to that. Accordingly, use the new macros to replace open-coded device links list walks in the core power management code. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Acked-by: Greg Kroah-Hartman Link: https://patch.msgid.link/1944671.tdWV9SEqCh@rafael.j.wysocki

PM: core: Annotate loops walking device links as _srcu

2025-09-06T15:16:06+00:00

Since SRCU is used for the protection of device link lists, the loops over device link lists in multiple places in drivers/base/power/main.c and in pm_runtime_get_suppliers() should be annotated as _srcu rather than as _rcu which is the case currently. Change the annotations accordingly. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Acked-by: Greg Kroah-Hartman Link: https://patch.msgid.link/2393512.ElGaqSPkdT@rafael.j.wysocki