Re: [PATCH] remoteproc: sysfs: fix race while updating recovery flag

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On 1/30/2023 4:21 AM, Satya Durga Srinivasu Prabhala wrote:
When multiple clients try to update the recovery flag, it is

Multiple user-space clients ?

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.

But your patch also adds locks for the case which does not update recovery flag..


Signed-off-by: Satya Durga Srinivasu Prabhala <quic_satyap@xxxxxxxxxxx>
---
  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);

is it really needed for this case?

  		rproc_trigger_recovery(rproc);
  	} else {
+		mutex_unlock(&rproc->lock);

same here..

  		return -EINVAL;
  	}

Do you also need to add lock for rproc_recovery_write in drivers/remoteproc/remoteproc_debugfs.c ?

-Mukesh



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