[PATCH 2/5] drm/xe: Add ref counting for xe_file

[Lucas De Marchi]

On Tue, Jul 09, 2024 at 12:28:43AM GMT, Matthew Brost wrote:
>On Mon, Jul 08, 2024 at 04:26:00PM -0700, Umesh Nerlige Ramappa wrote:
>> On Mon, Jul 08, 2024 at 05:52:00PM -0500, Lucas De Marchi wrote:
>> > On Mon, Jul 08, 2024 at 01:21:00PM GMT, Umesh Nerlige Ramappa wrote:
>> > > Add ref counting for xe_file.
>> > >
>> > > Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
>> > > ---
>> > > drivers/gpu/drm/xe/xe_device.c       |  7 +++++--
>> > > drivers/gpu/drm/xe/xe_device.h       | 12 ++++++++++++
>> > > drivers/gpu/drm/xe/xe_device_types.h |  3 +++
>> > > 3 files changed, 20 insertions(+), 2 deletions(-)
>> > >
>> > > diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
>> > > index babb697652d5..e6eacf1bcce0 100644
>> > > --- a/drivers/gpu/drm/xe/xe_device.c
>> > > +++ b/drivers/gpu/drm/xe/xe_device.c
>> > > @@ -87,11 +87,14 @@ static int xe_file_open(struct drm_device *dev, struct drm_file *file)
>> > > 	spin_unlock(&xe->clients.lock);
>> > >
>> > > 	file->driver_priv = xef;
>> > > +	kref_init(&xef->refcount);
>> > > +
>> > > 	return 0;
>> > > }
>> > >
>> > > -static void xe_file_destroy(struct xe_file *xef)
>> > > +void xe_file_destroy(struct kref *ref)
>> >
>> > why do you export this?  I don't think anybody should be calling
>> > xe_file_destroy() directly and this function being executed should only
>> > be the outcome of kref being 0. Also, if it's exported, it shouldn't
>> > really have struct kref as argument, but rather a struct xe_file
>> >
>> >
>> > > {
>> > > +	struct xe_file *xef = container_of(ref, struct xe_file, refcount);
>> > > 	struct xe_device *xe = xef->xe;
>> > > 	struct xe_vm *vm;
>> > > 	unsigned long idx;
>> > > @@ -130,7 +133,7 @@ static void xe_file_close(struct drm_device *dev, struct drm_file *file)
>> > > 		xe_exec_queue_put(q);
>> > > 	}
>> > >
>> > > -	xe_file_destroy(xef);
>> > > +	xe_file_put(xef);
>> > > }
>> > >
>> > > static const struct drm_ioctl_desc xe_ioctls[] = {
>> > > diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
>> > > index bb07f5669dbb..2a8b370b1fda 100644
>> > > --- a/drivers/gpu/drm/xe/xe_device.h
>> > > +++ b/drivers/gpu/drm/xe/xe_device.h
>> > > @@ -169,5 +169,17 @@ static inline bool xe_device_wedged(struct xe_device *xe)
>> > > }
>> > >
>> > > void xe_device_declare_wedged(struct xe_device *xe);
>> > > +void xe_file_destroy(struct kref *ref);
>> > > +
>> > > +static inline struct xe_file *xe_file_get(struct xe_file *xef)
>> > > +{
>> > > +	kref_get(&xef->refcount);
>> > > +	return xef;
>> > > +}
>> > > +
>> > > +static inline void xe_file_put(struct xe_file *xef)
>> >
>> > I think if you just make this non-inline, passing file_destroy and
>> > leave it in the same place, it should work.
>>
>> the put is called from xe_exec_queue.c and xe_vm.c also, so passing the
>> destroy may not work.
>>
>> Based on the patterns below, xe_file_put/xe_file_get will need to be moved
>> to xe_device.c and then exported. It looks cleaner, hoping that'w what you
>> mean.
>>
>> In xe_device.h:
>>
>> void xe_file_put(struct xe_file *xef);
>> struct xe_file *xe_file_get(struct xe_file *xef);

yes

>>
>
>My opinion is the way you have it is correct.
>
>Most of Xe is coded this way...
>
>mbrost at lstrano-desk:xe$ grep _get\( *.h | grep inline
>xe_bo.h:static inline struct xe_bo *xe_bo_get(struct xe_bo *bo)
>xe_device.h:static inline struct xe_file *xe_file_get(struct xe_file *xef)
>xe_exec_queue.h:static inline struct xe_exec_queue *xe_exec_queue_get(struct xe_exec_queue *q)
>xe_lrc.h:static inline struct xe_lrc *xe_lrc_get(struct xe_lrc *lrc)
>xe_sched_job.h:static inline struct xe_sched_job *xe_sched_job_get(struct xe_sched_job *job)
>xe_vm.h:static inline struct xe_vm *xe_vm_get(struct xe_vm *vm)
>
>I'm kinda confused by what Lucas is suggesting.

just don't make xe_file_destroy() non-static, which would basically
ignore the refcounting. xe_file_destroy() should rather be local to the
.c implementing xe_file_put().


Lucas De Marchi