In ultrasoc-smb drivers, smb_drv_data->spinlock can be held
during __schedule() by perf_event_task_sched_out()/in().

Since smb__drv_data->spinlock type is spinlock_t and
perf_event_task_sched_out()/in() is called after acquiring rq_lock,
which is raw_spinlock_t (an unsleepable lock),
this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable.

To address this, change type smb_drv_data->spinlock in ultrasoc-smb drivers,
which can be called by perf_event_task_sched_out()/in(),
from spinlock_t to raw_spinlock_t.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 drivers/hwtracing/coresight/ultrasoc-smb.c | 12 ++++++------
 drivers/hwtracing/coresight/ultrasoc-smb.h |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c
index dc3c9504dd7c..26cfc939e5bd 100644
--- a/drivers/hwtracing/coresight/ultrasoc-smb.c
+++ b/drivers/hwtracing/coresight/ultrasoc-smb.c
@@ -98,7 +98,7 @@ static int smb_open(struct inode *inode, struct file *file)
 	struct smb_drv_data *drvdata = container_of(file->private_data,
 					struct smb_drv_data, miscdev);
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	if (drvdata->reading)
 		return -EBUSY;
@@ -152,7 +152,7 @@ static int smb_release(struct inode *inode, struct file *file)
 	struct smb_drv_data *drvdata = container_of(file->private_data,
 					struct smb_drv_data, miscdev);
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 	drvdata->reading = false;
 
 	return 0;
@@ -245,7 +245,7 @@ static int smb_enable(struct coresight_device *csdev, enum cs_mode mode,
 	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
 	int ret = 0;
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	/* Do nothing, the trace data is reading by other interface now */
 	if (drvdata->reading)
@@ -280,7 +280,7 @@ static int smb_disable(struct coresight_device *csdev)
 {
 	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	if (drvdata->reading)
 		return -EBUSY;
@@ -378,7 +378,7 @@ static unsigned long smb_update_buffer(struct coresight_device *csdev,
 	if (!buf)
 		return 0;
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	/* Don't do anything if another tracer is using this sink. */
 	if (csdev->refcnt != 1)
@@ -563,7 +563,7 @@ static int smb_probe(struct platform_device *pdev)
 
 	smb_reset_buffer(drvdata);
 	platform_set_drvdata(pdev, drvdata);
-	spin_lock_init(&drvdata->spinlock);
+	raw_spin_lock_init(&drvdata->spinlock);
 	drvdata->pid = -1;
 
 	ret = smb_register_sink(pdev, drvdata);
diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.h b/drivers/hwtracing/coresight/ultrasoc-smb.h
index a91d39cfccb8..c4c111275627 100644
--- a/drivers/hwtracing/coresight/ultrasoc-smb.h
+++ b/drivers/hwtracing/coresight/ultrasoc-smb.h
@@ -115,7 +115,7 @@ struct smb_drv_data {
 	struct coresight_device	*csdev;
 	struct smb_data_buffer sdb;
 	struct miscdevice miscdev;
-	spinlock_t spinlock;
+	raw_spinlock_t spinlock;
 	bool reading;
 	pid_t pid;
 };
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}

Title of patch - this patch has nothing to do with cti_drvdata.

Mike


On Mon, 16 Dec 2024 at 11:50, Yeoreum Yun <yeoreum.yun@arm.com> wrote:
>
> In ultrasoc-smb drivers, smb_drv_data->spinlock can be held
> during __schedule() by perf_event_task_sched_out()/in().
>
> Since smb__drv_data->spinlock type is spinlock_t and
> perf_event_task_sched_out()/in() is called after acquiring rq_lock,
> which is raw_spinlock_t (an unsleepable lock),
> this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable.
>
> To address this, change type smb_drv_data->spinlock in ultrasoc-smb drivers,
> which can be called by perf_event_task_sched_out()/in(),
> from spinlock_t to raw_spinlock_t.
>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---
>  drivers/hwtracing/coresight/ultrasoc-smb.c | 12 ++++++------
>  drivers/hwtracing/coresight/ultrasoc-smb.h |  2 +-
>  2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c
> index dc3c9504dd7c..26cfc939e5bd 100644
> --- a/drivers/hwtracing/coresight/ultrasoc-smb.c
> +++ b/drivers/hwtracing/coresight/ultrasoc-smb.c
> @@ -98,7 +98,7 @@ static int smb_open(struct inode *inode, struct file *file)
>         struct smb_drv_data *drvdata = container_of(file->private_data,
>                                         struct smb_drv_data, miscdev);
>
> -       guard(spinlock)(&drvdata->spinlock);
> +       guard(raw_spinlock)(&drvdata->spinlock);
>
>         if (drvdata->reading)
>                 return -EBUSY;
> @@ -152,7 +152,7 @@ static int smb_release(struct inode *inode, struct file *file)
>         struct smb_drv_data *drvdata = container_of(file->private_data,
>                                         struct smb_drv_data, miscdev);
>
> -       guard(spinlock)(&drvdata->spinlock);
> +       guard(raw_spinlock)(&drvdata->spinlock);
>         drvdata->reading = false;
>
>         return 0;
> @@ -245,7 +245,7 @@ static int smb_enable(struct coresight_device *csdev, enum cs_mode mode,
>         struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
>         int ret = 0;
>
> -       guard(spinlock)(&drvdata->spinlock);
> +       guard(raw_spinlock)(&drvdata->spinlock);
>
>         /* Do nothing, the trace data is reading by other interface now */
>         if (drvdata->reading)
> @@ -280,7 +280,7 @@ static int smb_disable(struct coresight_device *csdev)
>  {
>         struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
>
> -       guard(spinlock)(&drvdata->spinlock);
> +       guard(raw_spinlock)(&drvdata->spinlock);
>
>         if (drvdata->reading)
>                 return -EBUSY;
> @@ -378,7 +378,7 @@ static unsigned long smb_update_buffer(struct coresight_device *csdev,
>         if (!buf)
>                 return 0;
>
> -       guard(spinlock)(&drvdata->spinlock);
> +       guard(raw_spinlock)(&drvdata->spinlock);
>
>         /* Don't do anything if another tracer is using this sink. */
>         if (csdev->refcnt != 1)
> @@ -563,7 +563,7 @@ static int smb_probe(struct platform_device *pdev)
>
>         smb_reset_buffer(drvdata);
>         platform_set_drvdata(pdev, drvdata);
> -       spin_lock_init(&drvdata->spinlock);
> +       raw_spin_lock_init(&drvdata->spinlock);
>         drvdata->pid = -1;
>
>         ret = smb_register_sink(pdev, drvdata);
> diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.h b/drivers/hwtracing/coresight/ultrasoc-smb.h
> index a91d39cfccb8..c4c111275627 100644
> --- a/drivers/hwtracing/coresight/ultrasoc-smb.h
> +++ b/drivers/hwtracing/coresight/ultrasoc-smb.h
> @@ -115,7 +115,7 @@ struct smb_drv_data {
>         struct coresight_device *csdev;
>         struct smb_data_buffer sdb;
>         struct miscdevice miscdev;
> -       spinlock_t spinlock;
> +       raw_spinlock_t spinlock;
>         bool reading;
>         pid_t pid;
>  };
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>


--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

Hi Mike.

> Title of patch - this patch has nothing to do with cti_drvdata.

Sorry. I'll fix this. Thanks
>
>
> On Mon, 16 Dec 2024 at 11:50, Yeoreum Yun <yeoreum.yun@arm.com> wrote:
> >
> > In ultrasoc-smb drivers, smb_drv_data->spinlock can be held
> > during __schedule() by perf_event_task_sched_out()/in().
> >
> > Since smb__drv_data->spinlock type is spinlock_t and
> > perf_event_task_sched_out()/in() is called after acquiring rq_lock,
> > which is raw_spinlock_t (an unsleepable lock),
> > this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable.
> >
> > To address this, change type smb_drv_data->spinlock in ultrasoc-smb drivers,
> > which can be called by perf_event_task_sched_out()/in(),
> > from spinlock_t to raw_spinlock_t.
> >
> > Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> > ---
> >  drivers/hwtracing/coresight/ultrasoc-smb.c | 12 ++++++------
> >  drivers/hwtracing/coresight/ultrasoc-smb.h |  2 +-
> >  2 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c
> > index dc3c9504dd7c..26cfc939e5bd 100644
> > --- a/drivers/hwtracing/coresight/ultrasoc-smb.c
> > +++ b/drivers/hwtracing/coresight/ultrasoc-smb.c
> > @@ -98,7 +98,7 @@ static int smb_open(struct inode *inode, struct file *file)
> >         struct smb_drv_data *drvdata = container_of(file->private_data,
> >                                         struct smb_drv_data, miscdev);
> >
> > -       guard(spinlock)(&drvdata->spinlock);
> > +       guard(raw_spinlock)(&drvdata->spinlock);
> >
> >         if (drvdata->reading)
> >                 return -EBUSY;
> > @@ -152,7 +152,7 @@ static int smb_release(struct inode *inode, struct file *file)
> >         struct smb_drv_data *drvdata = container_of(file->private_data,
> >                                         struct smb_drv_data, miscdev);
> >
> > -       guard(spinlock)(&drvdata->spinlock);
> > +       guard(raw_spinlock)(&drvdata->spinlock);
> >         drvdata->reading = false;
> >
> >         return 0;
> > @@ -245,7 +245,7 @@ static int smb_enable(struct coresight_device *csdev, enum cs_mode mode,
> >         struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
> >         int ret = 0;
> >
> > -       guard(spinlock)(&drvdata->spinlock);
> > +       guard(raw_spinlock)(&drvdata->spinlock);
> >
> >         /* Do nothing, the trace data is reading by other interface now */
> >         if (drvdata->reading)
> > @@ -280,7 +280,7 @@ static int smb_disable(struct coresight_device *csdev)
> >  {
> >         struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
> >
> > -       guard(spinlock)(&drvdata->spinlock);
> > +       guard(raw_spinlock)(&drvdata->spinlock);
> >
> >         if (drvdata->reading)
> >                 return -EBUSY;
> > @@ -378,7 +378,7 @@ static unsigned long smb_update_buffer(struct coresight_device *csdev,
> >         if (!buf)
> >                 return 0;
> >
> > -       guard(spinlock)(&drvdata->spinlock);
> > +       guard(raw_spinlock)(&drvdata->spinlock);
> >
> >         /* Don't do anything if another tracer is using this sink. */
> >         if (csdev->refcnt != 1)
> > @@ -563,7 +563,7 @@ static int smb_probe(struct platform_device *pdev)
> >
> >         smb_reset_buffer(drvdata);
> >         platform_set_drvdata(pdev, drvdata);
> > -       spin_lock_init(&drvdata->spinlock);
> > +       raw_spin_lock_init(&drvdata->spinlock);
> >         drvdata->pid = -1;
> >
> >         ret = smb_register_sink(pdev, drvdata);
> > diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.h b/drivers/hwtracing/coresight/ultrasoc-smb.h
> > index a91d39cfccb8..c4c111275627 100644
> > --- a/drivers/hwtracing/coresight/ultrasoc-smb.h
> > +++ b/drivers/hwtracing/coresight/ultrasoc-smb.h
> > @@ -115,7 +115,7 @@ struct smb_drv_data {
> >         struct coresight_device *csdev;
> >         struct smb_data_buffer sdb;
> >         struct miscdevice miscdev;
> > -       spinlock_t spinlock;
> > +       raw_spinlock_t spinlock;
> >         bool reading;
> >         pid_t pid;
> >  };
> > --
> > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
> >
>
>
> --
> Mike Leach
> Principal Engineer, ARM Ltd.
> Manchester Design Centre. UK