kernel/linux.git/drivers/base/power/main.c, branch v5.15.7

PM: sleep: Avoid calling put_device() under dpm_list_mtx

2021-11-18T18:17:17+00:00

commit 2aa36604e8243698ff22bd5fef0dd0c6bb07ba92 upstream. It is generally unsafe to call put_device() with dpm_list_mtx held, because the given device's release routine may carry out an action depending on that lock which then may deadlock, so modify the system-wide suspend and resume of devices to always drop dpm_list_mtx before calling put_device() (and adjust white space somewhat while at it). For instance, this prevents the following splat from showing up in the kernel log after a system resume in certain configurations: [ 3290.969514] ====================================================== [ 3290.969517] WARNING: possible circular locking dependency detected [ 3290.969519] 5.15.0+ #2420 Tainted: G S [ 3290.969523] ------------------------------------------------------ [ 3290.969525] systemd-sleep/4553 is trying to acquire lock: [ 3290.969529] ffff888117ab1138 ((wq_completion)hci0#2){+.+.}-{0:0}, at: flush_workqueue+0x87/0x4a0 [ 3290.969554] but task is already holding lock: [ 3290.969556] ffffffff8280fca8 (dpm_list_mtx){+.+.}-{3:3}, at: dpm_resume+0x12e/0x3e0 [ 3290.969571] which lock already depends on the new lock. [ 3290.969573] the existing dependency chain (in reverse order) is: [ 3290.969575] -> #3 (dpm_list_mtx){+.+.}-{3:3}: [ 3290.969583] __mutex_lock+0x9d/0xa30 [ 3290.969591] device_pm_add+0x2e/0xe0 [ 3290.969597] device_add+0x4d5/0x8f0 [ 3290.969605] hci_conn_add_sysfs+0x43/0xb0 [bluetooth] [ 3290.969689] hci_conn_complete_evt.isra.71+0x124/0x750 [bluetooth] [ 3290.969747] hci_event_packet+0xd6c/0x28a0 [bluetooth] [ 3290.969798] hci_rx_work+0x213/0x640 [bluetooth] [ 3290.969842] process_one_work+0x2aa/0x650 [ 3290.969851] worker_thread+0x39/0x400 [ 3290.969859] kthread+0x142/0x170 [ 3290.969865] ret_from_fork+0x22/0x30 [ 3290.969872] -> #2 (&hdev->lock){+.+.}-{3:3}: [ 3290.969881] __mutex_lock+0x9d/0xa30 [ 3290.969887] hci_event_packet+0xba/0x28a0 [bluetooth] [ 3290.969935] hci_rx_work+0x213/0x640 [bluetooth] [ 3290.969978] process_one_work+0x2aa/0x650 [ 3290.969985] worker_thread+0x39/0x400 [ 3290.969993] kthread+0x142/0x170 [ 3290.969999] ret_from_fork+0x22/0x30 [ 3290.970004] -> #1 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}: [ 3290.970013] process_one_work+0x27d/0x650 [ 3290.970020] worker_thread+0x39/0x400 [ 3290.970028] kthread+0x142/0x170 [ 3290.970033] ret_from_fork+0x22/0x30 [ 3290.970038] -> #0 ((wq_completion)hci0#2){+.+.}-{0:0}: [ 3290.970047] __lock_acquire+0x15cb/0x1b50 [ 3290.970054] lock_acquire+0x26c/0x300 [ 3290.970059] flush_workqueue+0xae/0x4a0 [ 3290.970066] drain_workqueue+0xa1/0x130 [ 3290.970073] destroy_workqueue+0x34/0x1f0 [ 3290.970081] hci_release_dev+0x49/0x180 [bluetooth] [ 3290.970130] bt_host_release+0x1d/0x30 [bluetooth] [ 3290.970195] device_release+0x33/0x90 [ 3290.970201] kobject_release+0x63/0x160 [ 3290.970211] dpm_resume+0x164/0x3e0 [ 3290.970215] dpm_resume_end+0xd/0x20 [ 3290.970220] suspend_devices_and_enter+0x1a4/0xba0 [ 3290.970229] pm_suspend+0x26b/0x310 [ 3290.970236] state_store+0x42/0x90 [ 3290.970243] kernfs_fop_write_iter+0x135/0x1b0 [ 3290.970251] new_sync_write+0x125/0x1c0 [ 3290.970257] vfs_write+0x360/0x3c0 [ 3290.970263] ksys_write+0xa7/0xe0 [ 3290.970269] do_syscall_64+0x3a/0x80 [ 3290.970276] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 3290.970284] other info that might help us debug this: [ 3290.970285] Chain exists of: (wq_completion)hci0#2 --> &hdev->lock --> dpm_list_mtx [ 3290.970297] Possible unsafe locking scenario: [ 3290.970299] CPU0 CPU1 [ 3290.970300] ---- ---- [ 3290.970302] lock(dpm_list_mtx); [ 3290.970306] lock(&hdev->lock); [ 3290.970310] lock(dpm_list_mtx); [ 3290.970314] lock((wq_completion)hci0#2); [ 3290.970319] *** DEADLOCK *** [ 3290.970321] 7 locks held by systemd-sleep/4553: [ 3290.970325] #0: ffff888103bcd448 (sb_writers#4){.+.+}-{0:0}, at: ksys_write+0xa7/0xe0 [ 3290.970341] #1: ffff888115a14488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x103/0x1b0 [ 3290.970355] #2: ffff888100f719e0 (kn->active#233){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x10c/0x1b0 [ 3290.970369] #3: ffffffff82661048 (autosleep_lock){+.+.}-{3:3}, at: state_store+0x12/0x90 [ 3290.970384] #4: ffffffff82658ac8 (system_transition_mutex){+.+.}-{3:3}, at: pm_suspend+0x9f/0x310 [ 3290.970399] #5: ffffffff827f2a48 (acpi_scan_lock){+.+.}-{3:3}, at: acpi_suspend_begin+0x4c/0x80 [ 3290.970416] #6: ffffffff8280fca8 (dpm_list_mtx){+.+.}-{3:3}, at: dpm_resume+0x12e/0x3e0 [ 3290.970428] stack backtrace: [ 3290.970431] CPU: 3 PID: 4553 Comm: systemd-sleep Tainted: G S 5.15.0+ #2420 [ 3290.970438] Hardware name: Dell Inc. XPS 13 9380/0RYJWW, BIOS 1.5.0 06/03/2019 [ 3290.970441] Call Trace: [ 3290.970446] dump_stack_lvl+0x44/0x57 [ 3290.970454] check_noncircular+0x105/0x120 [ 3290.970468] ? __lock_acquire+0x15cb/0x1b50 [ 3290.970474] __lock_acquire+0x15cb/0x1b50 [ 3290.970487] lock_acquire+0x26c/0x300 [ 3290.970493] ? flush_workqueue+0x87/0x4a0 [ 3290.970503] ? __raw_spin_lock_init+0x3b/0x60 [ 3290.970510] ? lockdep_init_map_type+0x58/0x240 [ 3290.970519] flush_workqueue+0xae/0x4a0 [ 3290.970526] ? flush_workqueue+0x87/0x4a0 [ 3290.970544] ? drain_workqueue+0xa1/0x130 [ 3290.970552] drain_workqueue+0xa1/0x130 [ 3290.970561] destroy_workqueue+0x34/0x1f0 [ 3290.970572] hci_release_dev+0x49/0x180 [bluetooth] [ 3290.970624] bt_host_release+0x1d/0x30 [bluetooth] [ 3290.970687] device_release+0x33/0x90 [ 3290.970695] kobject_release+0x63/0x160 [ 3290.970705] dpm_resume+0x164/0x3e0 [ 3290.970710] ? dpm_resume_early+0x251/0x3b0 [ 3290.970718] dpm_resume_end+0xd/0x20 [ 3290.970723] suspend_devices_and_enter+0x1a4/0xba0 [ 3290.970737] pm_suspend+0x26b/0x310 [ 3290.970746] state_store+0x42/0x90 [ 3290.970755] kernfs_fop_write_iter+0x135/0x1b0 [ 3290.970764] new_sync_write+0x125/0x1c0 [ 3290.970777] vfs_write+0x360/0x3c0 [ 3290.970785] ksys_write+0xa7/0xe0 [ 3290.970794] do_syscall_64+0x3a/0x80 [ 3290.970803] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 3290.970811] RIP: 0033:0x7f41b1328164 [ 3290.970819] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 80 00 00 00 00 8b 05 4a d2 2c 00 48 63 ff 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 f3 c3 66 90 55 53 48 89 d5 48 89 f3 48 83 [ 3290.970824] RSP: 002b:00007ffe6ae21b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 3290.970831] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f41b1328164 [ 3290.970836] RDX: 0000000000000004 RSI: 000055965e651070 RDI: 0000000000000004 [ 3290.970839] RBP: 000055965e651070 R08: 000055965e64f390 R09: 00007f41b1e3d1c0 [ 3290.970843] R10: 000000000000000a R11: 0000000000000246 R12: 0000000000000004 [ 3290.970846] R13: 0000000000000001 R14: 000055965e64f2b0 R15: 0000000000000004 Cc: All applicable Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM: sleep: Do not let "syscore" devices runtime-suspend during system transitions

2021-11-18T18:15:59+00:00

commit 928265e3601cde78c7e0a3e518a93b27defed3b1 upstream. There is no reason to allow "syscore" devices to runtime-suspend during system-wide PM transitions, because they are subject to the same possible failure modes as any other devices in that respect. Accordingly, change device_prepare() and device_complete() to call pm_runtime_get_noresume() and pm_runtime_put(), respectively, for "syscore" devices too. Fixes: 057d51a1268f ("Merge branch 'pm-sleep'") Signed-off-by: Rafael J. Wysocki Cc: 3.10+ # 3.10+ Reviewed-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman

PM: sleep: core: Avoid setting power.must_resume to false

2021-09-07T19:18:34+00:00

There are variables(power.may_skip_resume and dev->power.must_resume) and DPM_FLAG_MAY_SKIP_RESUME flags to control the resume of devices after a system wide suspend transition. Setting the DPM_FLAG_MAY_SKIP_RESUME flag means that the driver allows its "noirq" and "early" resume callbacks to be skipped if the device can be left in suspend after a system-wide transition into the working state. PM core determines that the driver's "noirq" and "early" resume callbacks should be skipped or not with dev_pm_skip_resume() function by checking power.may_skip_resume variable. power.must_resume variable is getting set to false in __device_suspend() function without checking device's DPM_FLAG_MAY_SKIP_RESUME settings. In problematic scenario, where all the devices in the suspend_late stage are successful and some device can fail to suspend in suspend_noirq phase. So some devices successfully suspended in suspend_late stage are not getting chance to execute __device_suspend_noirq() to set dev->power.must_resume variable to true and not getting resumed in early_resume phase. Add a check for device's DPM_FLAG_MAY_SKIP_RESUME flag before setting power.must_resume variable in __device_suspend function. Fixes: 6e176bf8d461 ("PM: sleep: core: Do not skip callbacks in the resume phase") Signed-off-by: Prasad Sodagudi Signed-off-by: Rafael J. Wysocki

PM: sleep: Use ktime_us_delta() in initcall_debug_report()

2021-07-01T16:44:02+00:00

Use ktime_us_delta() to make the debug log more precise instead of shifting the return value of ktime_to_ns() applied to a ktime_sub() result by 10 bit positions to the right. Signed-off-by: Mark-PK Tsai [ rjw: Changelog rewrite, subject edits ] Signed-off-by: Rafael J. Wysocki

PM: sleep: Use dev_printk() when possible

2021-01-27T18:21:17+00:00

Use dev_printk() when possible to make messages more consistent with other device-related messages. Signed-off-by: Bjorn Helgaas Signed-off-by: Rafael J. Wysocki

PM: sleep: Add dev_wakeup_path() helper

2020-11-23T17:34:55+00:00

Add dev_wakeup_path() helper to avoid to spread dev->power.wakeup_path test in drivers. Signed-off-by: Patrice Chotard Reviewed-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki

PM: sleep: Print driver flags for all devices during suspend/resume

2020-11-10T18:41:40+00:00

Currently there are 4 driver flags to control system suspend/resume behavior: DPM_FLAG_NO_DIRECT_COMPLETE, DPM_FLAG_SMART_PREPARE, DPM_FLAG_SMART_SUSPEND and DPM_FLAG_MAY_SKIP_RESUME. Print these flags during suspend/resume so as to get a brief understanding of the expected behavior of each device, and to facilitate suspend/resume debugging/tuning. To enable this tracing: echo 'file drivers/base/power/main.c +p' > /sys/kernel/debug/dynamic_debug/control Signed-off-by: Chen Yu [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki

PM: sleep: remove unreachable break

2020-10-22T16:43:31+00:00

A break following a return statement is pointless, so drop it. Signed-off-by: Tom Rix [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki

PM: sleep: core: Fix the handling of pending runtime resume requests

2020-08-25T14:28:23+00:00

It has been reported that system-wide suspend may be aborted in the absence of any wakeup events due to unforseen interactions of it with the runtume PM framework. One failing scenario is when there are multiple devices sharing an ACPI power resource and runtime-resume needs to be carried out for one of them during system-wide suspend (for example, because it needs to be reconfigured before the whole system goes to sleep). In that case, the runtime-resume of that device involves turning the ACPI power resource "on" which in turn causes runtime-resume requests to be queued up for all of the other devices sharing it. Those requests go to the runtime PM workqueue which is frozen during system-wide suspend, so they are not actually taken care of until the resume of the whole system, but the pm_runtime_barrier() call in __device_suspend() sees them and triggers system wakeup events for them which then cause the system-wide suspend to be aborted if wakeup source objects are in active use. Of course, the logic that leads to triggering those wakeup events is questionable in the first place, because clearly there are cases in which a pending runtime resume request for a device is not connected to any real wakeup events in any way (like the one above). Moreover, it is racy, because the device may be resuming already by the time the pm_runtime_barrier() runs and so if the driver doesn't take care of signaling the wakeup event as appropriate, it will be lost. However, if the driver does take care of that, the extra pm_wakeup_event() call in the core is redundant. Accordingly, drop the conditional pm_wakeup_event() call fron __device_suspend() and make the latter call pm_runtime_barrier() alone. Also modify the comment next to that call to reflect the new code and extend it to mention the need to avoid unwanted interactions between runtime PM and system-wide device suspend callbacks. Fixes: 1e2ef05bb8cf8 ("PM: Limit race conditions between runtime PM and system sleep (v2)") Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern Reported-by: Utkarsh H Patel Tested-by: Utkarsh H Patel Tested-by: Pengfei Xu Cc: All applicable

kernel: rename show_stack_loglvl() => show_stack()

2020-06-09T16:39:13+00:00

Now the last users of show_stack() got converted to use an explicit log level, show_stack_loglvl() can drop it's redundant suffix and become once again well known show_stack(). Signed-off-by: Dmitry Safonov Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com Signed-off-by: Linus Torvalds