Commit 38c04b47 authored by Maarten Lankhorst's avatar Maarten Lankhorst Committed by Rodrigo Vivi
Browse files

drm/xe: Use atomic instead of mutex for xe_device_mem_access_ongoing 



xe_guc_ct_fast_path() is called from an irq context, and cannot lock
the mutex used by xe_device_mem_access_ongoing().

Fortunately it is easy to fix, and the atomic guarantees are good enough
to ensure xe->mem_access.hold_rpm is set before last ref is dropped.

As far as I can tell, the runtime ref in device access should be
killable, but don't dare to do it yet.

Signed-off-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: default avatarMatthew Brost <matthew.brost@intel.com>
Acked-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
parent 044f0cfb

drivers/gpu/drm/xe/xe_device.c

+8 −10
Original line number Diff line number Diff line
@@ -206,8 +206,6 @@ struct xe_device *xe_device_create(struct pci_dev *pdev, 
	if (err)

		goto err_put;



	drmm_mutex_init(&xe->drm, &xe->mem_access.lock);



	return xe;



err_put:
@@ -354,25 +352,25 @@ u32 xe_device_ccs_bytes(struct xe_device *xe, u64 size) 
void xe_device_mem_access_get(struct xe_device *xe)

{

	bool resumed = xe_pm_runtime_resume_if_suspended(xe);

	int ref = atomic_inc_return(&xe->mem_access.ref);



	mutex_lock(&xe->mem_access.lock);

	if (xe->mem_access.ref++ == 0)

	if (ref == 1)

		xe->mem_access.hold_rpm = xe_pm_runtime_get_if_active(xe);

	mutex_unlock(&xe->mem_access.lock);



	/* The usage counter increased if device was immediately resumed */

	if (resumed)

		xe_pm_runtime_put(xe);



	XE_WARN_ON(xe->mem_access.ref == S32_MAX);

	XE_WARN_ON(ref == S32_MAX);

}



void xe_device_mem_access_put(struct xe_device *xe)

{

	mutex_lock(&xe->mem_access.lock);

	if (--xe->mem_access.ref == 0 && xe->mem_access.hold_rpm)

	bool hold = xe->mem_access.hold_rpm;

	int ref = atomic_dec_return(&xe->mem_access.ref);



	if (!ref && hold)

		xe_pm_runtime_put(xe);

	mutex_unlock(&xe->mem_access.lock);



	XE_WARN_ON(xe->mem_access.ref < 0);

	XE_WARN_ON(ref < 0);

}

drivers/gpu/drm/xe/xe_device.h

+4 −10
Original line number Diff line number Diff line
@@ -90,20 +90,14 @@ static inline struct xe_force_wake * gt_to_fw(struct xe_gt *gt) 
void xe_device_mem_access_get(struct xe_device *xe);

void xe_device_mem_access_put(struct xe_device *xe);



static inline void xe_device_assert_mem_access(struct xe_device *xe)

static inline bool xe_device_mem_access_ongoing(struct xe_device *xe)

{

	XE_WARN_ON(!xe->mem_access.ref);

	return atomic_read(&xe->mem_access.ref);

}



static inline bool xe_device_mem_access_ongoing(struct xe_device *xe)

static inline void xe_device_assert_mem_access(struct xe_device *xe)

{

	bool ret;



	mutex_lock(&xe->mem_access.lock);

	ret = xe->mem_access.ref;

	mutex_unlock(&xe->mem_access.lock);



	return ret;

	XE_WARN_ON(!xe_device_mem_access_ongoing(xe));

}



static inline bool xe_device_in_fault_mode(struct xe_device *xe)

drivers/gpu/drm/xe/xe_device_types.h

+1 −3
Original line number Diff line number Diff line
@@ -184,10 +184,8 @@ struct xe_device { 
	 * triggering additional actions when they occur.

	 */

	struct {

		/** @lock: protect the ref count */

		struct mutex lock;

		/** @ref: ref count of memory accesses */

		s32 ref;

		atomic_t ref;

		/** @hold_rpm: need to put rpm ref back at the end */

		bool hold_rpm;

	} mem_access;