On Mon, Oct 21, 2024 at 09:12:47AM -0600, Mathieu Poirier wrote: > Hi Mukesh, > > On Wed, Oct 16, 2024 at 10:25:46AM +0530, Mukesh Ojha wrote: > > Multiple call to glink_subdev_stop() for the same remoteproc can happen > > if rproc_stop() fails from Process-A that leaves the rproc state to > > RPROC_CRASHED state later a call to recovery_store from user space in > > Process B triggers rproc_trigger_recovery() of the same remoteproc to > > recover it results in NULL pointer dereference issue in > > qcom_glink_smem_unregister(). > > > > There is other side to this issue if we want to fix this via adding a > > NULL check on glink->edge which does not guarantees that the remoteproc > > will recover in second call from Process B as it has failed in the first > > Process A during SMC shutdown call and may again fail at the same call > > and rproc can not recover for such case. > > > > Add a new rproc state RPROC_DEFUNCT i.e., non recoverable state of > > remoteproc and the only way to recover from it via system restart. > > > > Process-A Process-B > > > > fatal error interrupt happens > > > > rproc_crash_handler_work() > > mutex_lock_interruptible(&rproc->lock); > > ... > > > > rproc->state = RPROC_CRASHED; > > ... > > mutex_unlock(&rproc->lock); > > > > rproc_trigger_recovery() > > mutex_lock_interruptible(&rproc->lock); > > > > adsp_stop() > > qcom_q6v5_pas 20c00000.remoteproc: failed to shutdown: -22 > > remoteproc remoteproc3: can't stop rproc: -22 > > mutex_unlock(&rproc->lock); > > Ok, that can happen. > > > > > echo enabled > /sys/class/remoteproc/remoteprocX/recovery > > recovery_store() > > rproc_trigger_recovery() > > mutex_lock_interruptible(&rproc->lock); > > rproc_stop() > > glink_subdev_stop() > > qcom_glink_smem_unregister() ==| > > | > > V > > I am missing some information here but I will _assume_ this is caused by > glink->edge being set to NULL [1] when glink_subdev_stop() is first called by > process A. Instead of adding a new state to the core I think a better idea > would be to add a check for a NULL value on @smem in > qcom_glink_smem_unregister(). This is a problem that should be fixed in the > driver rather than the core. > > [1]. https://elixir.bootlin.com/linux/v6.12-rc4/source/drivers/remoteproc/qcom_common.c#L213 I did the same here [1] but after discussion with Bjorn, realized that remoteproc might not even recover and may fail in the second attempt as well and only way is reboot of the machine. [1] https://lore.kernel.org/lkml/20240925103351.1628788-1-quic_mojha@xxxxxxxxxxx/ > > > Unable to handle kernel NULL pointer dereference > > at virtual address 0000000000000358 > > > > Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx> > > --- > > Changes in v3: > > - Fix kernel test reported error. > > > > Changes in v2: > > - Removed NULL pointer check instead added a new state to signify > > non-recoverable state of remoteproc. > > > > drivers/remoteproc/remoteproc_core.c | 3 ++- > > drivers/remoteproc/remoteproc_sysfs.c | 1 + > > include/linux/remoteproc.h | 5 ++++- > > 3 files changed, 7 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c > > index f276956f2c5c..c4e14503b971 100644 > > --- a/drivers/remoteproc/remoteproc_core.c > > +++ b/drivers/remoteproc/remoteproc_core.c > > @@ -1727,6 +1727,7 @@ static int rproc_stop(struct rproc *rproc, bool crashed) > > /* power off the remote processor */ > > ret = rproc->ops->stop(rproc); > > if (ret) { > > + rproc->state = RPROC_DEFUNCT; > > dev_err(dev, "can't stop rproc: %d\n", ret); > > return ret; > > } > > @@ -1839,7 +1840,7 @@ int rproc_trigger_recovery(struct rproc *rproc) > > return ret; > > > > /* State could have changed before we got the mutex */ > > - if (rproc->state != RPROC_CRASHED) > > + if (rproc->state == RPROC_DEFUNCT || rproc->state != RPROC_CRASHED) > > goto unlock_mutex; > > The problem is that rproc_trigger_recovery() an only be called once for a > remoteproc, something that modifies the state machine and may introduce backward > compatibility issues for other remote processor implementations. > I missed one more point to add here which i tried to highlight in second version[2] that setting of RPROC_DEFUNCT should happen for this case from vendor remoteproc driver and not at the core and that should take care of the backward compatibility. [2] https://lore.kernel.org/lkml/Zw2CAbMozI8vu4SL@xxxxxxxxxxxxxxxxxxxxxxxxx/ -Mukesh > Thanks, > Mathieu > > > > > dev_err(dev, "recovering %s\n", rproc->name); > > diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c > > index 138e752c5e4e..5f722b4576b2 100644 > > --- a/drivers/remoteproc/remoteproc_sysfs.c > > +++ b/drivers/remoteproc/remoteproc_sysfs.c > > @@ -171,6 +171,7 @@ static const char * const rproc_state_string[] = { > > [RPROC_DELETED] = "deleted", > > [RPROC_ATTACHED] = "attached", > > [RPROC_DETACHED] = "detached", > > + [RPROC_DEFUNCT] = "defunct", > > [RPROC_LAST] = "invalid", > > }; > > > > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h > > index b4795698d8c2..3e4ba06c6a9a 100644 > > --- a/include/linux/remoteproc.h > > +++ b/include/linux/remoteproc.h > > @@ -417,6 +417,8 @@ struct rproc_ops { > > * has attached to it > > * @RPROC_DETACHED: device has been booted by another entity and waiting > > * for the core to attach to it > > + * @RPROC_DEFUNCT: device neither crashed nor responding to any of the > > + * requests and can only recover on system restart. > > * @RPROC_LAST: just keep this one at the end > > * > > * Please note that the values of these states are used as indices > > @@ -433,7 +435,8 @@ enum rproc_state { > > RPROC_DELETED = 4, > > RPROC_ATTACHED = 5, > > RPROC_DETACHED = 6, > > - RPROC_LAST = 7, > > + RPROC_DEFUNCT = 7, > > + RPROC_LAST = 8, > > }; > > > > /** > > -- > > 2.34.1 > >
