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drm/xe: Use atomic instead of mutex for xe_device_mem_access_ongoing

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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: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Maarten Lankhorst 2023-02-28 11:17:30 +01:00 committed by Rodrigo Vivi
parent 044f0cfb19
commit 38c04b47ce
3 changed files with 15 additions and 25 deletions
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20
drivers/gpu/drm/xe/xe_device.c
View File

@ -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)
xe_pm_runtime_put(xe);
mutex_unlock(&xe->mem_access.lock);
bool hold = xe->mem_access.hold_rpm;
int ref = atomic_dec_return(&xe->mem_access.ref);
XE_WARN_ON(xe->mem_access.ref < 0);
if (!ref && hold)
xe_pm_runtime_put(xe);
XE_WARN_ON(ref < 0);
}

16
drivers/gpu/drm/xe/xe_device.h
View File

@ -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)
{
XE_WARN_ON(!xe->mem_access.ref);
}
static inline bool xe_device_mem_access_ongoing(struct xe_device *xe)
{
bool ret;
return atomic_read(&xe->mem_access.ref);
}
mutex_lock(&xe->mem_access.lock);
ret = xe->mem_access.ref;
mutex_unlock(&xe->mem_access.lock);
return ret;
static inline void xe_device_assert_mem_access(struct xe_device *xe)
{
XE_WARN_ON(!xe_device_mem_access_ongoing(xe));
}
static inline bool xe_device_in_fault_mode(struct xe_device *xe)

4
drivers/gpu/drm/xe/xe_device_types.h
View File

@ -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;