From e246518aa24f1460902725e97d0abf574aec6ade Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Tue, 26 Aug 2025 13:43:47 +0200 Subject: [PATCH] PM: sleep: annotate RCU list iterations These iterations require the read lock, otherwise RCU lockdep will splat: ============================= WARNING: suspicious RCU usage 6.17.0-rc3-00014-g31419c045d64 #6 Tainted: G O ----------------------------- drivers/base/power/main.c:1333 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 5 locks held by rtcwake/547: #0: 00000000643ab418 (sb_writers#6){.+.+}-{0:0}, at: file_start_write+0x2b/0x3a #1: 0000000067a0ca88 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x181/0x24b #2: 00000000631eac40 (kn->active#3){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x191/0x24b #3: 00000000609a1308 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend+0xaf/0x30b #4: 0000000060c0fdb0 (device_links_srcu){.+.+}-{0:0}, at: device_links_read_lock+0x75/0x98 stack backtrace: CPU: 0 UID: 0 PID: 547 Comm: rtcwake Tainted: G O 6.17.0-rc3-00014-g31419c045d64 #6 VOLUNTARY Tainted: [O]=OOT_MODULE Stack: 223721b3a80 6089eac6 00000001 00000001 ffffff00 6089eac6 00000535 6086e528 721b3ac0 6003c294 00000000 60031fc0 Call Trace: [<600407ed>] show_stack+0x10e/0x127 [<6003c294>] dump_stack_lvl+0x77/0xc6 [<6003c2fd>] dump_stack+0x1a/0x20 [<600bc2f8>] lockdep_rcu_suspicious+0x116/0x13e [<603d8ea1>] dpm_async_suspend_superior+0x117/0x17e [<603d980f>] device_suspend+0x528/0x541 [<603da24b>] dpm_suspend+0x1a2/0x267 [<603da837>] dpm_suspend_start+0x5d/0x72 [<600ca0c9>] suspend_devices_and_enter+0xab/0x736 [...] Add the fourth argument to the iteration to annotate this and avoid the splat. Fixes: 06799631d522 ("PM: sleep: Make async suspend handle suppliers like parents") Fixes: ed18738fff02 ("PM: sleep: Make async resume handle consumers like children") Signed-off-by: Johannes Berg Link: https://patch.msgid.link/20250826134348.aba79f6e6299.I9ecf55da46ccf33778f2c018a82e1819d815b348@changeid Signed-off-by: Rafael J. Wysocki --- drivers/base/power/main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index dbf5456cd891..2ea6e05e6ec9 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -675,7 +675,7 @@ static void dpm_async_resume_subordinate(struct device *dev, async_func_t func) idx = device_links_read_lock(); /* Start processing the device's "async" consumers. */ - list_for_each_entry_rcu(link, &dev->links.consumers, s_node) + list_for_each_entry_rcu_locked(link, &dev->links.consumers, s_node) if (READ_ONCE(link->status) != DL_STATE_DORMANT) dpm_async_with_cleanup(link->consumer, func); @@ -1330,7 +1330,7 @@ static void dpm_async_suspend_superior(struct device *dev, async_func_t func) idx = device_links_read_lock(); /* Start processing the device's "async" suppliers. */ - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) + list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node) if (READ_ONCE(link->status) != DL_STATE_DORMANT) dpm_async_with_cleanup(link->supplier, func); -- 2.25.1