linux-kernel - [PATCH] remoteproc: sysfs: fix race while updating recovery flag

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Message-ID: <20230129225106.10606-1-quic_satyap@quicinc.com>
Date:   Sun, 29 Jan 2023 14:51:06 -0800
From:   Satya Durga Srinivasu Prabhala <quic_satyap@...cinc.com>
To:     <andersson@...nel.org>, <mathieu.poirier@...aro.org>
CC:     Satya Durga Srinivasu Prabhala <quic_satyap@...cinc.com>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>
Subject: [PATCH] remoteproc: sysfs: fix race while updating recovery flag

When multiple clients try to update the recovery flag, it is
possible that, race condition would lead to undesired results
as updates to recovery flag isn't protected by any mechanism
today. To avoid such issues, take remoteproc mutex lock before
updating recovery flag and release the lock once done.

Signed-off-by: Satya Durga Srinivasu Prabhala <quic_satyap@...cinc.com>
---
 drivers/remoteproc/remoteproc_sysfs.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
index 8c7ea8922638..ec37176e1589 100644
--- a/drivers/remoteproc/remoteproc_sysfs.c
+++ b/drivers/remoteproc/remoteproc_sysfs.c
@@ -48,16 +48,21 @@ static ssize_t recovery_store(struct device *dev,
 {
 	struct rproc *rproc = to_rproc(dev);
 
+	mutex_lock(&rproc->lock);
 	if (sysfs_streq(buf, "enabled")) {
 		/* change the flag and begin the recovery process if needed */
 		rproc->recovery_disabled = false;
+		mutex_unlock(&rproc->lock);
 		rproc_trigger_recovery(rproc);
 	} else if (sysfs_streq(buf, "disabled")) {
 		rproc->recovery_disabled = true;
+		mutex_unlock(&rproc->lock);
 	} else if (sysfs_streq(buf, "recover")) {
 		/* begin the recovery process without changing the flag */
+		mutex_unlock(&rproc->lock);
 		rproc_trigger_recovery(rproc);
 	} else {
+		mutex_unlock(&rproc->lock);
 		return -EINVAL;
 	}
 
-- 
2.38.1