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Message-ID: <cfe32c1c-6d9b-1c74-c7d1-6597591edf77@quicinc.com>
Date: Mon, 22 May 2023 15:03:14 +0530
From: Mukesh Ojha <quic_mojha@...cinc.com>
To: Vignesh Viswanathan <quic_viswanat@...cinc.com>,
<agross@...nel.org>, <andersson@...nel.org>,
<konrad.dybcio@...aro.org>, <mathieu.poirier@...aro.org>,
<linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-remoteproc@...r.kernel.org>
CC: <quic_srichara@...cinc.com>, <quic_varada@...cinc.com>,
<quic_kathirav@...cinc.com>, <quic_devipriy@...cinc.com>,
<quic_sjaganat@...cinc.com>
Subject: Re: [PATCH] remoteproc: qcom: Add NOTIFY_FATAL event type to SSR
subdevice
On 5/3/2023 4:56 PM, Mukesh Ojha wrote:
>
>
> On 5/3/2023 11:51 AM, Vignesh Viswanathan wrote:
>> 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.
>>
>> 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.
>
> This was one of valid use case we encounter in android, We have some
> other way of doing the same thing without core kernel change with
> something called early notifiers.
>
> https://git.codelinaro.org/clo/la/kernel/msm-5.15/-/commit/7583d24de337aa1bf7c375a7da706af9b995b9a1#a840754ebb0e24e88adbf48177e1abd0830b72d2
>
> https://git.codelinaro.org/clo/la/kernel/msm-5.15/-/commit/257de41c63a5a51a081cc7887cdaa4a46e4d1744
>
> But good to address this if possible.
Ack the idea of early notifier;
But here, atomic does not guarantees it to be atomic.
Acked-by: Mukesh Ojha <quic_mojha@...cinc.com>
-- Mukesh
>
> -Mukesh
>>
>> Signed-off-by: Vignesh Viswanathan <quic_viswanat@...cinc.com>
>> ---
>> 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(+)
>>
>> diff --git a/drivers/remoteproc/qcom_common.c
>> b/drivers/remoteproc/qcom_common.c
>> index a0d4238492e9..76542229aeb6 100644
>> --- a/drivers/remoteproc/qcom_common.c
>> +++ b/drivers/remoteproc/qcom_common.c
>> @@ -84,6 +84,7 @@ 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;
>> };
>> @@ -366,6 +367,7 @@ 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);
>> @@ -417,6 +419,51 @@ 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
>> + * @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);
>> @@ -467,6 +514,18 @@ 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
>> @@ -493,6 +552,7 @@ 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 695cce218e8c..3de0ece158ea 100644
>> --- a/drivers/remoteproc/remoteproc_core.c
>> +++ b/drivers/remoteproc/remoteproc_core.c
>> @@ -1139,6 +1139,16 @@ 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
>> @@ -2687,6 +2697,8 @@ 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 fe8978eb69f1..f3c0e0103e81 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;
>> +}
>> +
>> +static inline int qcom_unregister_ssr_atomic_notifier(void *notify,
>> + struct notifier_block *nb)
>> +{
>> + return 0;
>> +}
>> #endif
>> #endif
>
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