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Wysocki" , Daniel Lezcano , Amit Kucheria , Zhang Rui , Matthias Brugger , AngeloGioacchino Del Regno CC: , , , Bo Ye , , , , Subject: [PATCH] Subject: thermal: Fix potential race condition in suspend/resume Date: Sat, 16 Sep 2023 19:33:26 +0800 Message-ID: <20230916113327.85693-1-bo.ye@mediatek.com> X-Mailer: git-send-email 2.17.0 MIME-Version: 1.0 X-TM-AS-Product-Ver: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-AS-Result: No-10--4.682700-8.000000 X-TMASE-MatchedRID: 53RBOU84eqlniBBtNEnVPdsfxZpQv2qMFAr+wPWe7jEmu2XKsBcW8Rwb B+iCKX6CIpXyAy0omPBsNi0cjuzvUperG0eDQRp7Bu2zRCSrLjYrHkgIan9a0YrVCk5dmxbq3qM rf/AypQVwZC1i9Jj6zoeduB0bUkzgz7wL+9mPXSV1e7Xbb6Im2kyQ5fRSh265GNAPebYwJ/uta8 DXVXWIqYJi3vP75Z5QBFQhScLIoJe6zsztxuMjKKwxbZnudyr7vJ9Xvh5CmT6bKItl61J/yfJvo cwUrWp7MFRQ7RYz5mULbigRnpKlKTpcQTtiHDgWg4zVeOPsni4XPwbj6LWT34wDFrwDUXDgxGGc duInXkiBFbtJie1T3EMMprcbiest X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10--4.682700-8.000000 X-TMASE-Version: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-SNTS-SMTP: 24FFF8FE059C8449768942D227F29DF4D6B35F708D3BEFDA6387961263ED06362000:8 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230916_043356_157303_8C35C267 X-CRM114-Status: GOOD ( 11.37 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org From: "yugang.wang" Body: This patch fixes a race condition during system resume. It occurs if the system is exiting a suspend state and a user is trying to register/unregister a thermal zone concurrently. The root cause is that both actions access the `thermal_tz_list`. In detail: 1. At PM_POST_SUSPEND during the resume, the system reads all thermal zones in `thermal_tz_list`, then resets and updates their temperatures. 2. When registering/unregistering a thermal zone, the `thermal_tz_list` gets manipulated. These two actions might occur concurrently, causing a race condition. To solve this issue, we introduce a mutex lock to protect `thermal_tz_list` from being modified while it's being read and updated during the resume from suspend. Kernel oops excerpt related to this fix: [ 5201.869845] [T316822] pc: [0xffffffeb7d4876f0] mutex_lock+0x34/0x170 [ 5201.869856] [T316822] lr: [0xffffffeb7ca98a84] thermal_pm_notify+0xd4/0x26c [... cut for brevity ...] [ 5201.871061] [T316822] suspend_prepare+0x150/0x470 [ 5201.871067] [T316822] enter_state+0x84/0x6f4 [ 5201.871076] [T316822] state_store+0x15c/0x1e8 Change-Id: Ifdbdecba17093f91eab7e36ce04b46d311ca6568 Signed-off-by: yugang.wang Signed-off-by: Bo Ye --- drivers/thermal/thermal_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c index 8717a3343512..a7a18ed57b6d 100644 --- a/drivers/thermal/thermal_core.c +++ b/drivers/thermal/thermal_core.c @@ -1529,12 +1529,14 @@ static int thermal_pm_notify(struct notifier_block *nb, case PM_POST_HIBERNATION: case PM_POST_RESTORE: case PM_POST_SUSPEND: + mutex_lock(&thermal_list_lock); atomic_set(&in_suspend, 0); list_for_each_entry(tz, &thermal_tz_list, node) { thermal_zone_device_init(tz); thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED); } + mutex_unlock(&thermal_list_lock); break; default: break;