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Message-ID: <20230916113327.85693-1-bo.ye@mediatek.com>
Date: Sat, 16 Sep 2023 19:33:26 +0800
From: Bo Ye <bo.ye@...iatek.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Amit Kucheria <amitk@...nel.org>,
Zhang Rui <rui.zhang@...el.com>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com>
CC: <yugang.wang@...iatek.com>, <yongdong.zhang@...iatek.com>,
<browse.zhang@...iatek.com>, Bo Ye <bo.ye@...iatek.com>,
<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-mediatek@...ts.infradead.org>
Subject: [PATCH] Subject: thermal: Fix potential race condition in suspend/resume
From: "yugang.wang" <yugang.wang@...iatek.com>
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 <yugang.wang@...iatek.com>
Signed-off-by: Bo Ye <bo.ye@...iatek.com>
---
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;
--
2.17.0
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