Add qcom_smem_bust_hwspin_lock_by_host to enable remoteproc to bust the
hwspin_lock owned by smem. In the event the remoteproc crashes
unexpectedly, the remoteproc driver can invoke this API to try and bust
the hwspin_lock and release the lock if still held by the remoteproc
device.
Signed-off-by: Chris Lew <[email protected]>
---
drivers/soc/qcom/smem.c | 28 ++++++++++++++++++++++++++++
include/linux/soc/qcom/smem.h | 2 ++
2 files changed, 30 insertions(+)
diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
index 7191fa0c087f..683599990387 100644
--- a/drivers/soc/qcom/smem.c
+++ b/drivers/soc/qcom/smem.c
@@ -359,6 +359,34 @@ static struct qcom_smem *__smem;
/* Timeout (ms) for the trylock of remote spinlocks */
#define HWSPINLOCK_TIMEOUT 1000
+/* The qcom hwspinlock id is always plus one from the smem host id */
+#define SMEM_HOST_ID_TO_HWSPINLOCK_ID(__x) ((__x) + 1)
+
+/**
+ * qcom_smem_bust_hwspin_lock_by_host() - bust the smem hwspinlock for an smem host id
+ * @host: remote processor id
+ *
+ * Busts the hwspin_lock for the given smem host id. This helper is intended for remoteproc drivers
+ * that manage remoteprocs with an equivalent smem driver instance in the remote firmware. Drivers
+ * can force a release of the smem hwspin_lock if the rproc unexpectedly goes into a bad state.
+ *
+ * Context: Process context.
+ *
+ * Returns: 0 on success, otherwise negative errno.
+ */
+int qcom_smem_bust_hwspin_lock_by_host(unsigned host)
+{
+ if (!__smem)
+ return -EPROBE_DEFER;
+
+ /* This function is for remote procs, so ignore SMEM_HOST_APPS */
+ if (host == SMEM_HOST_APPS ||host >= SMEM_HOST_COUNT)
+ return -EINVAL;
+
+ return hwspin_lock_bust(__smem->hwlock, SMEM_HOST_ID_TO_HWSPINLOCK_ID(host));
+}
+EXPORT_SYMBOL_GPL(qcom_smem_bust_hwspin_lock_by_host);
+
/**
* qcom_smem_is_available() - Check if SMEM is available
*
diff --git a/include/linux/soc/qcom/smem.h b/include/linux/soc/qcom/smem.h
index a36a3b9d4929..959eea0812bb 100644
--- a/include/linux/soc/qcom/smem.h
+++ b/include/linux/soc/qcom/smem.h
@@ -14,4 +14,6 @@ phys_addr_t qcom_smem_virt_to_phys(void *p);
int qcom_smem_get_soc_id(u32 *id);
+int qcom_smem_bust_hwspin_lock_by_host(unsigned host);
+
#endif
--
2.25.1
On Fri, May 24, 2024 at 06:26:42PM GMT, Chris Lew wrote:
> Add qcom_smem_bust_hwspin_lock_by_host to enable remoteproc to bust the
> hwspin_lock owned by smem. In the event the remoteproc crashes
> unexpectedly, the remoteproc driver can invoke this API to try and bust
> the hwspin_lock and release the lock if still held by the remoteproc
> device.
>
> Signed-off-by: Chris Lew <[email protected]>
> ---
> drivers/soc/qcom/smem.c | 28 ++++++++++++++++++++++++++++
> include/linux/soc/qcom/smem.h | 2 ++
> 2 files changed, 30 insertions(+)
>
> diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
> index 7191fa0c087f..683599990387 100644
> --- a/drivers/soc/qcom/smem.c
> +++ b/drivers/soc/qcom/smem.c
> @@ -359,6 +359,34 @@ static struct qcom_smem *__smem;
> /* Timeout (ms) for the trylock of remote spinlocks */
> #define HWSPINLOCK_TIMEOUT 1000
>
> +/* The qcom hwspinlock id is always plus one from the smem host id */
> +#define SMEM_HOST_ID_TO_HWSPINLOCK_ID(__x) ((__x) + 1)
> +
> +/**
> + * qcom_smem_bust_hwspin_lock_by_host() - bust the smem hwspinlock for an smem host id
> + * @host: remote processor id
> + *
> + * Busts the hwspin_lock for the given smem host id. This helper is intended for remoteproc drivers
> + * that manage remoteprocs with an equivalent smem driver instance in the remote firmware. Drivers
> + * can force a release of the smem hwspin_lock if the rproc unexpectedly goes into a bad state.
Please wrap these at 80 characters.
> + *
> + * Context: Process context.
> + *
> + * Returns: 0 on success, otherwise negative errno.
> + */
> +int qcom_smem_bust_hwspin_lock_by_host(unsigned host)
> +{
> + if (!__smem)
> + return -EPROBE_DEFER;
This would be called at a time where -EPROBE_DEFER isn't appropriate,
the client should invoke qcom_smem_is_available() at probe time to guard
against this.
> +
> + /* This function is for remote procs, so ignore SMEM_HOST_APPS */
> + if (host == SMEM_HOST_APPS ||host >= SMEM_HOST_COUNT)
Missing <space> after ||
Regards,
Bjorn
> + return -EINVAL;
> +
> + return hwspin_lock_bust(__smem->hwlock, SMEM_HOST_ID_TO_HWSPINLOCK_ID(host));
> +}
> +EXPORT_SYMBOL_GPL(qcom_smem_bust_hwspin_lock_by_host);
> +
> /**
> * qcom_smem_is_available() - Check if SMEM is available
> *
> diff --git a/include/linux/soc/qcom/smem.h b/include/linux/soc/qcom/smem.h
> index a36a3b9d4929..959eea0812bb 100644
> --- a/include/linux/soc/qcom/smem.h
> +++ b/include/linux/soc/qcom/smem.h
> @@ -14,4 +14,6 @@ phys_addr_t qcom_smem_virt_to_phys(void *p);
>
> int qcom_smem_get_soc_id(u32 *id);
>
> +int qcom_smem_bust_hwspin_lock_by_host(unsigned host);
> +
> #endif
>
> --
> 2.25.1
>
On 5/28/2024 2:55 PM, Bjorn Andersson wrote:
> On Fri, May 24, 2024 at 06:26:42PM GMT, Chris Lew wrote:
>> Add qcom_smem_bust_hwspin_lock_by_host to enable remoteproc to bust the
>> hwspin_lock owned by smem. In the event the remoteproc crashes
>> unexpectedly, the remoteproc driver can invoke this API to try and bust
>> the hwspin_lock and release the lock if still held by the remoteproc
>> device.
>>
>> Signed-off-by: Chris Lew <[email protected]>
>> ---
>> drivers/soc/qcom/smem.c | 28 ++++++++++++++++++++++++++++
>> include/linux/soc/qcom/smem.h | 2 ++
>> 2 files changed, 30 insertions(+)
>>
>> diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
>> index 7191fa0c087f..683599990387 100644
>> --- a/drivers/soc/qcom/smem.c
>> +++ b/drivers/soc/qcom/smem.c
..
>> + *
>> + * Context: Process context.
>> + *
>> + * Returns: 0 on success, otherwise negative errno.
>> + */
>> +int qcom_smem_bust_hwspin_lock_by_host(unsigned host)
>> +{
>> + if (!__smem)
>> + return -EPROBE_DEFER;
>
> This would be called at a time where -EPROBE_DEFER isn't appropriate,
> the client should invoke qcom_smem_is_available() at probe time to guard
> against this.
>
Should we keep the null pointer check to prevent null pointer
dereference and return 0? Or would it be better to allow the null
pointer deference to go through so we can catch misuse of the API and
ask clients to use qcom_smem_is_available()?
On Tue, May 28, 2024 at 03:50:25PM -0700, Chris Lew wrote:
>
>
> On 5/28/2024 2:55 PM, Bjorn Andersson wrote:
> > On Fri, May 24, 2024 at 06:26:42PM GMT, Chris Lew wrote:
> > > Add qcom_smem_bust_hwspin_lock_by_host to enable remoteproc to bust the
> > > hwspin_lock owned by smem. In the event the remoteproc crashes
> > > unexpectedly, the remoteproc driver can invoke this API to try and bust
> > > the hwspin_lock and release the lock if still held by the remoteproc
> > > device.
> > >
> > > Signed-off-by: Chris Lew <[email protected]>
> > > ---
> > > drivers/soc/qcom/smem.c | 28 ++++++++++++++++++++++++++++
> > > include/linux/soc/qcom/smem.h | 2 ++
> > > 2 files changed, 30 insertions(+)
> > >
> > > diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
> > > index 7191fa0c087f..683599990387 100644
> > > --- a/drivers/soc/qcom/smem.c
> > > +++ b/drivers/soc/qcom/smem.c
> ...
> > > + *
> > > + * Context: Process context.
> > > + *
> > > + * Returns: 0 on success, otherwise negative errno.
> > > + */
> > > +int qcom_smem_bust_hwspin_lock_by_host(unsigned host)
> > > +{
> > > + if (!__smem)
> > > + return -EPROBE_DEFER;
> >
> > This would be called at a time where -EPROBE_DEFER isn't appropriate,
> > the client should invoke qcom_smem_is_available() at probe time to guard
> > against this.
> >
>
> Should we keep the null pointer check to prevent null pointer dereference
> and return 0? Or would it be better to allow the null pointer deference to
> go through so we can catch misuse of the API and ask clients to use
> qcom_smem_is_available()?
>
I like the helpful callstack you get from the NULL pointer
dereference...
Regards,
Bjorn