linux-kernel - [PATCH] PM / suspend: Abort suspend if somebody holds wakelock

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Date:   Wed,  6 Oct 2021 21:57:20 +0530
From:   Mukesh Ojha <mojha@...eaurora.org>
To:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     rafael@...nel.org, len.brown@...el.com, pavel@....cz,
        Mukesh Ojha <mojha@...eaurora.org>
Subject: [PATCH] PM / suspend: Abort suspend if somebody holds wakelock

There could be a scenario, where request_firmware() call results in
user land process trying to load firmwares into memory and
parallely one miscellaneous process is trying to invoke manual
suspend and due to which user mode helper gets disabled during
freezing of processes and that aborts loading of firmware even
though request_firmware() thread has taken wakelock.

Although, we are checking for any wakeup event inside
try_to_freeze_tasks() but that could be too late for the
above scenario.

Let's add a check before freezing/disable user land process in
suspend path.

Signed-off-by: Mukesh Ojha <mojha@...eaurora.org>
---
 kernel/power/process.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 37401c9..3e0d3d6 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -124,6 +124,9 @@ int freeze_processes(void)
 {
 	int error;

+	if (pm_wakeup_pending())
+		return -EBUSY;
+
 	error = __usermodehelper_disable(UMH_FREEZING);
 	if (error)
 		return error;
-- 
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