[PATCH v1 08/12] PM: sleep: stats: Use locking in dpm_save_failed_dev()

From: Rafael J. Wysocki
Date: Mon Jan 22 2024 - 06:45:49 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Because dpm_save_failed_dev() may be called simultaneously by multiple
failing device PM functions, the state of the suspend_stats fields
updated by it may become inconsistent.

Prevent that from happening by using a lock in dpm_save_failed_dev().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
kernel/power/main.c | 5 +++++
1 file changed, 5 insertions(+)

Index: linux-pm/kernel/power/main.c
===================================================================
--- linux-pm.orig/kernel/power/main.c
+++ linux-pm/kernel/power/main.c
@@ -323,13 +323,18 @@ struct suspend_stats {
};

static struct suspend_stats suspend_stats;
+static DEFINE_MUTEX(suspend_stats_lock);

void dpm_save_failed_dev(const char *name)
{
+ mutex_lock(&suspend_stats_lock);
+
strscpy(suspend_stats.failed_devs[suspend_stats.last_failed_dev],
name, sizeof(suspend_stats.failed_devs[0]));
suspend_stats.last_failed_dev++;
suspend_stats.last_failed_dev %= REC_FAILED_NUM;
+
+ mutex_unlock(&suspend_stats_lock);
}

void dpm_save_failed_step(enum suspend_stat_step step)