Re: [PATCH v2] remoteproc: sysfs/debugfs: fix race while updating recovery flag

[Satya Durga Srinivasu Prabhala]

On 2/1/23 4:05 AM, Mukesh Ojha wrote:
> On 2/1/2023 11:16 AM, Satya Durga Srinivasu Prabhala wrote:
> > 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@xxxxxxxxxxx>
>
> LGTM.
>
> Reviewed-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>

Thanks Mukesh.

Hi Bjorn,

Can you help cross check?

Best,
Satya

> -Mukesh
> > ---
> > v1 -> v2:
> > - addressed comments from Mukesh Ojha
> >    1. take & release lock only while updating recovery flag
> >    2. update debugfs
> >
> >   drivers/remoteproc/remoteproc_debugfs.c | 4 ++++
> >   drivers/remoteproc/remoteproc_sysfs.c   | 4 ++++
> >   2 files changed, 8 insertions(+)
> >
> > diff --git a/drivers/remoteproc/remoteproc_debugfs.c 
> > b/drivers/remoteproc/remoteproc_debugfs.c
> > index b86c1d09c70c..2c44d375024e 100644
> > --- a/drivers/remoteproc/remoteproc_debugfs.c
> > +++ b/drivers/remoteproc/remoteproc_debugfs.c
> > @@ -226,10 +226,14 @@ rproc_recovery_write(struct file *filp, const 
> > char __user *user_buf,
> >
> >       if (!strncmp(buf, "enabled", count)) {
> >           /* change the flag and begin the recovery process if needed */
> > +        mutex_lock(&rproc->lock);
> >           rproc->recovery_disabled = false;
> > +        mutex_unlock(&rproc->lock);
> >           rproc_trigger_recovery(rproc);
> >       } else if (!strncmp(buf, "disabled", count)) {
> > +        mutex_lock(&rproc->lock);
> >           rproc->recovery_disabled = true;
> > +        mutex_unlock(&rproc->lock);
> >       } else if (!strncmp(buf, "recover", count)) {
> >           /* begin the recovery process without changing the flag */
> >           rproc_trigger_recovery(rproc);
> > diff --git a/drivers/remoteproc/remoteproc_sysfs.c 
> > b/drivers/remoteproc/remoteproc_sysfs.c
> > index 8c7ea8922638..628e0de9a132 100644
> > --- a/drivers/remoteproc/remoteproc_sysfs.c
> > +++ b/drivers/remoteproc/remoteproc_sysfs.c
> > @@ -50,10 +50,14 @@ static ssize_t recovery_store(struct device *dev,
> >
> >       if (sysfs_streq(buf, "enabled")) {
> >           /* change the flag and begin the recovery process if needed */
> > +        mutex_lock(&rproc->lock);
> >           rproc->recovery_disabled = false;
> > +        mutex_unlock(&rproc->lock);
> >           rproc_trigger_recovery(rproc);
> >       } else if (sysfs_streq(buf, "disabled")) {
> > +        mutex_lock(&rproc->lock);
> >           rproc->recovery_disabled = true;
> > +        mutex_unlock(&rproc->lock);
> >       } else if (sysfs_streq(buf, "recover")) {
> >           /* begin the recovery process without changing the flag */
> >           rproc_trigger_recovery(rproc);