On 6/5/2026 2:42 AM, Jeff Johnson wrote:
> On 8/19/2024 11:09 PM, Gokul Sriram Palanisamy wrote:
>> From: Vignesh Viswanathan <[email protected]>
>>
>> Currently the SSR subdevice notifies the client driver on crash of the
>> rproc from the recovery workqueue using the BEFORE_SHUTDOWN event.
>> However, the client driver might be interested to know that the device
>> has crashed immediately to pause any further transactions with the
>> rproc. This calls for an event to be sent to the driver in the IRQ
>> context as soon as the rproc crashes.
>>
>> Add NOTIFY_FATAL event to SSR subdevice to atomically notify rproc has
>> crashed to the client driver. The client driver in this scenario is a
>> ath Wi-Fi driver which is continuously queuing data to the remoteproc and
>> needs to know if remoteproc crashes as soon as possible to stop queuing
>> further data and also dump some debug statistics on the driver side that
>> could potentially help in debug of why the remoteproc crashed.
>>
>> Validated the event in IPQ9574 and IPQ5332 by forcing the rproc to crash
>> and ensuring the registered notifier function receives the notification
>> in IRQ context.
>>
>> The client driver in this scenario is a Wi-Fi driver which is continuously
>> queuing data to the remoteproc and needs to know if remoteproc crashes
>> as soon as possible to stop queuing further data and also dump some
>> debug statistics on the driver side that could potentially help in
>> debug of why the remoteproc crashed.
>>
>> Signed-off-by: Vignesh Viswanathan <[email protected]>
>> Acked-by: Mukesh Ojha <[email protected]>
>> Signed-off-by: Gokul Sriram Palanisamy <[email protected]>
>> ---
>> changes since v1:
>> - No changes. Rebased on top of linux-next.
>> - We will now have a user for this notifier, ath12k.
>>
>> drivers/remoteproc/qcom_common.c | 60 +++++++++++++++++++++++++++
>> drivers/remoteproc/remoteproc_core.c | 12 ++++++
>> include/linux/remoteproc.h | 3 ++
>> include/linux/remoteproc/qcom_rproc.h | 17 ++++++++
>> 4 files changed, 92 insertions(+)
>
> Core review comments below assisted by Claude:claude-sonnet-4-6
>>
>> diff --git a/drivers/remoteproc/qcom_common.c
>> b/drivers/remoteproc/qcom_common.c
>> index 8c8688f99f0a..6efee422cc23 100644
>> --- a/drivers/remoteproc/qcom_common.c
>> +++ b/drivers/remoteproc/qcom_common.c
>> @@ -86,6 +86,7 @@ struct minidump_global_toc {
>> struct qcom_ssr_subsystem {
>> const char *name;
>> struct srcu_notifier_head notifier_list;
>> + struct atomic_notifier_head atomic_notifier_list;
>> struct list_head list;
>> };
>>
>> @@ -377,6 +378,7 @@ static struct qcom_ssr_subsystem
>> *qcom_ssr_get_subsys(const char *name)
>> }
>> info->name = kstrdup_const(name, GFP_KERNEL);
>> srcu_init_notifier_head(&info->notifier_list);
>> + ATOMIC_INIT_NOTIFIER_HEAD(&info->atomic_notifier_list);
>>
>> /* Add to global notification list */
>> list_add_tail(&info->list, &qcom_ssr_subsystem_list);
>> @@ -428,6 +430,51 @@ int qcom_unregister_ssr_notifier(void *notify, struct
>> notifier_block *nb)
>> }
>> EXPORT_SYMBOL_GPL(qcom_unregister_ssr_notifier);
>>
>> +/**
>> + * qcom_register_ssr_atomic_notifier() - register SSR Atomic notification
>> + * handler
>> + * @name: Subsystem's SSR name
>> + * @nb: notifier_block to be invoked upon subsystem's state change
>> + *
>> + * This registers the @nb notifier block as part the atomic notifier
>> + * chain for a remoteproc associated with @name. The notifier block's
>> callback
>> + * will be invoked when the remote processor crashes in atomic context
>> before
>> + * the recovery process is queued.
>> + *
>> + * Return: a subsystem cookie on success, ERR_PTR on failure.
>> + */
>> +void *qcom_register_ssr_atomic_notifier(const char *name,
>> + struct notifier_block *nb)
>> +{
>> + struct qcom_ssr_subsystem *info;
>> +
>> + info = qcom_ssr_get_subsys(name);
>> + if (IS_ERR(info))
>> + return info;
>> +
>> + atomic_notifier_chain_register(&info->atomic_notifier_list, nb);
>> +
>> + return &info->atomic_notifier_list;
>> +}
>> +EXPORT_SYMBOL_GPL(qcom_register_ssr_atomic_notifier);
>> +
>> +/**
>> + * qcom_unregister_ssr_atomic_notifier() - unregister SSR Atomic
>> notification
>> + * handler
>> + * @notify: subsystem cookie returned from qcom_register_ssr_notifier
>
> @notify kdoc parameter references wrong function name
>
> Should be qcom_register_ssr_atomic_notifier. The two notifier chains are
> independent; notify from qcom_register_ssr_notifier points to
> &info->notifier_list (SRCU), while notify from
> qcom_register_ssr_atomic_notifier points to &info->atomic_notifier_list.
> Passing the wrong cookie to atomic_notifier_chain_unregister would corrupt the
> wrong list. The doc misleads callers about which cookie to pass.
Ack.
>
>> + * @nb: notifier_block to unregister
>> + *
>> + * This function will unregister the notifier from the atomic notifier
>> + * chain.
>> + *
>> + * Return: 0 on success, %ENOENT otherwise.
>> + */
>> +int qcom_unregister_ssr_atomic_notifier(void *notify, struct notifier_block
>> *nb)
>> +{
>> + return atomic_notifier_chain_unregister(notify, nb);
>> +}
>> +EXPORT_SYMBOL_GPL(qcom_unregister_ssr_atomic_notifier);
>> +
>> static int ssr_notify_prepare(struct rproc_subdev *subdev)
>> {
>> struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
>> @@ -478,6 +525,18 @@ static void ssr_notify_unprepare(struct rproc_subdev
>> *subdev)
>> QCOM_SSR_AFTER_SHUTDOWN, &data);
>> }
>>
>> +static void ssr_notify_crash(struct rproc_subdev *subdev)
>> +{
>> + struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
>> + struct qcom_ssr_notify_data data = {
>> + .name = ssr->info->name,
>> + .crashed = true,
>> + };
>> +
>> + atomic_notifier_call_chain(&ssr->info->atomic_notifier_list,
>> + QCOM_SSR_NOTIFY_CRASH, &data);
>> +}
>> +
>> /**
>> * qcom_add_ssr_subdev() - register subdevice as restart notification source
>> * @rproc: rproc handle
>> @@ -504,6 +563,7 @@ void qcom_add_ssr_subdev(struct rproc *rproc, struct
>> qcom_rproc_ssr *ssr,
>> ssr->subdev.start = ssr_notify_start;
>> ssr->subdev.stop = ssr_notify_stop;
>> ssr->subdev.unprepare = ssr_notify_unprepare;
>> + ssr->subdev.notify_crash = ssr_notify_crash;
>>
>> rproc_add_subdev(rproc, &ssr->subdev);
>> }
>> diff --git a/drivers/remoteproc/remoteproc_core.c
>> b/drivers/remoteproc/remoteproc_core.c
>> index f276956f2c5c..1828831e0e77 100644
>> --- a/drivers/remoteproc/remoteproc_core.c
>> +++ b/drivers/remoteproc/remoteproc_core.c
>> @@ -1140,6 +1140,16 @@ static void rproc_unprepare_subdevices(struct rproc
>> *rproc)
>> }
>> }
>>
>> +static void rproc_notify_crash_subdevices(struct rproc *rproc)
>> +{
>> + struct rproc_subdev *subdev;
>> +
>> + list_for_each_entry_reverse(subdev, &rproc->subdevs, node) {
>> + if (subdev->notify_crash)
>> + subdev->notify_crash(subdev);
>> + }
>> +}
>> +
>> /**
>> * rproc_alloc_registered_carveouts() - allocate all carveouts registered
>> * in the list
>> @@ -2712,6 +2722,8 @@ void rproc_report_crash(struct rproc *rproc, enum
>> rproc_crash_type type)
>> dev_err(&rproc->dev, "crash detected in %s: type %s\n",
>> rproc->name, rproc_crash_to_string(type));
>>
>> + rproc_notify_crash_subdevices(rproc);
>> +
>> queue_work(rproc_recovery_wq, &rproc->crash_handler);
>> }
>> EXPORT_SYMBOL(rproc_report_crash);
>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>> index b4795698d8c2..5101a7ec01bb 100644
>> --- a/include/linux/remoteproc.h
>> +++ b/include/linux/remoteproc.h
>> @@ -596,6 +596,8 @@ struct rproc {
>> * @stop: stop function, called before the rproc is stopped; the @crashed
>> * parameter indicates if this originates from a recovery
>> * @unprepare: unprepare function, called after the rproc has been stopped
>> + * @notify_crash: notify_crash function, called in atomic context to notify
>> + * rproc has crashed and recovery is about to start
>> */
>> struct rproc_subdev {
>> struct list_head node;
>> @@ -604,6 +606,7 @@ struct rproc_subdev {
>> int (*start)(struct rproc_subdev *subdev);
>> void (*stop)(struct rproc_subdev *subdev, bool crashed);
>> void (*unprepare)(struct rproc_subdev *subdev);
>> + void (*notify_crash)(struct rproc_subdev *subdev);
>> };
>>
>> /* we currently support only two vrings per rvdev */
>> diff --git a/include/linux/remoteproc/qcom_rproc.h
>> b/include/linux/remoteproc/qcom_rproc.h
>> index 82b211518136..f3d06900f297 100644
>> --- a/include/linux/remoteproc/qcom_rproc.h
>> +++ b/include/linux/remoteproc/qcom_rproc.h
>> @@ -11,12 +11,14 @@ struct notifier_block;
>> * @QCOM_SSR_AFTER_POWERUP: Remoteproc is running (start stage)
>> * @QCOM_SSR_BEFORE_SHUTDOWN: Remoteproc crashed or shutting down
>> (stop stage)
>> * @QCOM_SSR_AFTER_SHUTDOWN: Remoteproc is down (unprepare stage)
>> + * @QCOM_SSR_NOTIFY_CRASH: Remoteproc crashed
>> */
>> enum qcom_ssr_notify_type {
>> QCOM_SSR_BEFORE_POWERUP,
>> QCOM_SSR_AFTER_POWERUP,
>> QCOM_SSR_BEFORE_SHUTDOWN,
>> QCOM_SSR_AFTER_SHUTDOWN,
>> + QCOM_SSR_NOTIFY_CRASH,
>> };
>>
>> struct qcom_ssr_notify_data {
>> @@ -29,6 +31,10 @@ struct qcom_ssr_notify_data {
>> void *qcom_register_ssr_notifier(const char *name, struct notifier_block
>> *nb);
>> int qcom_unregister_ssr_notifier(void *notify, struct notifier_block *nb);
>>
>> +void *qcom_register_ssr_atomic_notifier(const char *name,
>> + struct notifier_block *nb);
>> +int qcom_unregister_ssr_atomic_notifier(void *notify,
>> + struct notifier_block *nb);
>> #else
>>
>> static inline void *qcom_register_ssr_notifier(const char *name,
>> @@ -43,6 +49,17 @@ static inline int qcom_unregister_ssr_notifier(void
>> *notify,
>> return 0;
>> }
>>
>> +static inline void *qcom_register_ssr_atomic_notifier(const char *name,
>> + struct notifier_block *nb)
>> +{
>> + return 0;
>
> qcom_register_ssr_atomic_notifier disabled stub returns integer 0 instead of
> NULL
>
> The function return type is void *. Returning integer 0 rather than NULL will
> trigger a -Wint-conversion compiler warning in kernel builds (return makes
> pointer from integer without a cast). The immediately preceding sibling stub
> qcom_register_ssr_notifier correctly returns NULL.
>
> Fix: return NULL;
Ack.
Thanks,
Vignesh
>
>
>> +}
>> +
>> +static inline int qcom_unregister_ssr_atomic_notifier(void *notify,
>> + struct notifier_block *nb)
>> +{
>> + return 0;
>> +}
>> #endif
>>
>> #endif
>
>
