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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Nov 2025 17:22:12.5242 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7fb096e2-6983-4a3f-0e62-08de1afd86f7 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF000023D4.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PPF73BED5E32 On 11/2/25 2:54 AM, Zhongqiu Han wrote: > On 10/28/2025 12:57 PM, Tanmay Shah wrote: >> Current attach on recovery mechanism loads the clean resource table >> during recovery, but doesn't re-allocate the resources. RPMsg >> communication will fail after recovery due to this. Fix this >> incorrect behavior by doing the full detach and attach of remote >> processor during the recovery. This will load the clean resource table >> and re-allocate all the resources, which will set up correct vring >> information in the resource table. >> >> Signed-off-by: Tanmay Shah >> --- >>   drivers/remoteproc/remoteproc_core.c | 22 +++++++++++++--------- >>   1 file changed, 13 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/ >> remoteproc/remoteproc_core.c >> index aada2780b343..f5b078fe056a 100644 >> --- a/drivers/remoteproc/remoteproc_core.c >> +++ b/drivers/remoteproc/remoteproc_core.c >> @@ -1777,11 +1777,11 @@ static int rproc_attach_recovery(struct rproc >> *rproc) >>   { >>       int ret; >> -    ret = __rproc_detach(rproc); >> +    ret = rproc_detach(rproc); >>       if (ret) >>           return ret; >> -    return __rproc_attach(rproc); >> +    return rproc_attach(rproc); >>   } >>   static int rproc_boot_recovery(struct rproc *rproc) >> @@ -1829,6 +1829,9 @@ int rproc_trigger_recovery(struct rproc *rproc) >>       struct device *dev = &rproc->dev; >>       int ret; >> +    if (rproc_has_feature(rproc, RPROC_FEAT_ATTACH_ON_RECOVERY)) >> +        return rproc_attach_recovery(rproc); >> + >>       ret = mutex_lock_interruptible(&rproc->lock); > > Hi Tanmay, > > I have a concern about this patch, specifically regarding the locking > behavior and potential race conditions introduced by the early return in > rproc_trigger_recovery(), by calling rproc_attach_recovery() directly > and bypassing the original mutex_lock_interruptible() in > rproc_trigger_recovery(), the recovery flow now executes rproc_attach() > without holding rproc->lock. > > This could potentially lead to race conditions if other threads are > accessing or modifying shared resources concurrently.For example, one > possible scenario is: > > > state_store/rproc_trigger_auto_boot > -->rproc_boot >    -->ret = mutex_lock_interruptible(&rproc->lock);    <--(4) >    -->if (rproc->state == RPROC_DETACHED) { >        -->ret = rproc_attach(rproc);                   <--(5) >       } >    -->mutex_unlock(&rproc->lock); > > > rproc_trigger_recovery > -->rproc_attach_recovery >    -->rproc_detach >       -->ret = mutex_lock_interruptible(&rproc->lock); <--(1) >       -->ret = __rproc_detach(rproc); >       -->rproc->state = RPROC_DETACHED;                <--(2) >       -->mutex_unlock(&rproc->lock);                   <--(3) >   -->return rproc_attach(rproc);                       <--(6) > > As shown in stack (5) and (6), two threads may simultaneously > execute the rproc_attach() function, which could lead to a race > condition. > > Please feel free to correct me, thanks~ Hello, Thanks for your reviews. I did not face this problem during verification on board, but your assessment is correct. I have been thinking to use rproc_boot instead of rproc_attach. It provides locking mechanism, and then also increases power refcount. https://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux.git/tree/drivers/remoteproc/remoteproc_core.c?h=for-next#n1904 I hope that will address your concern. Thanks, Tanmay > > >>       if (ret) >>           return ret; >> @@ -1839,10 +1842,7 @@ int rproc_trigger_recovery(struct rproc *rproc) >>       dev_err(dev, "recovering %s\n", rproc->name); >> -    if (rproc_has_feature(rproc, RPROC_FEAT_ATTACH_ON_RECOVERY)) >> -        ret = rproc_attach_recovery(rproc); >> -    else >> -        ret = rproc_boot_recovery(rproc); >> +    ret = rproc_boot_recovery(rproc); >>   unlock_mutex: >>       mutex_unlock(&rproc->lock); >> @@ -1860,6 +1860,7 @@ static void rproc_crash_handler_work(struct >> work_struct *work) >>   { >>       struct rproc *rproc = container_of(work, struct rproc, >> crash_handler); >>       struct device *dev = &rproc->dev; >> +    int ret; >>       dev_dbg(dev, "enter %s\n", __func__); >> @@ -1883,8 +1884,11 @@ static void rproc_crash_handler_work(struct >> work_struct *work) >>       mutex_unlock(&rproc->lock); >> -    if (!rproc->recovery_disabled) >> -        rproc_trigger_recovery(rproc); >> +    if (!rproc->recovery_disabled) { >> +        ret = rproc_trigger_recovery(rproc); >> +        if (ret) >> +            dev_warn(dev, "rproc recovery failed, err %d\n", ret); >> +    } >>   out: >>       pm_relax(rproc->dev.parent); >> @@ -2057,7 +2061,7 @@ int rproc_detach(struct rproc *rproc) >>           return ret; >>       } >> -    if (rproc->state != RPROC_ATTACHED) { >> +    if (rproc->state != RPROC_ATTACHED && rproc->state != >> RPROC_CRASHED) { >>           ret = -EINVAL; >>           goto out; >>       } > >