drm/i915: Mark up all locked waiters

In the next patch we want to handle reset directly by a locked waiter in
order to avoid issues with returning before the reset is handled. To
handle the reset, we must first know whether we hold the struct_mutex.
If we do not hold the struct_mtuex we can not perform the reset, but we do
not block the reset worker either (and so we can just continue to wait for
request completion) - otherwise we must relinquish the mutex.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160909131201.16673-10-chris@chris-wilson.co.uk

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index 479896e..def3572 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -222,7 +222,8 @@ int i915_wait_request(struct drm_i915_gem_request *req,
 		      s64 *timeout,
 		      struct intel_rps_client *rps)
 	__attribute__((nonnull(1)));
-#define I915_WAIT_INTERRUPTIBLE BIT(0)
+#define I915_WAIT_INTERRUPTIBLE	BIT(0)
+#define I915_WAIT_LOCKED	BIT(1) /* struct_mutex held, handle GPU reset */
 
 static inline u32 intel_engine_get_seqno(struct intel_engine_cs *engine);
 
@@ -576,7 +577,9 @@ i915_gem_active_wait(const struct i915_gem_active *active, struct mutex *mutex)
 	if (!request)
 		return 0;
 
-	return i915_wait_request(request, I915_WAIT_INTERRUPTIBLE, NULL, NULL);
+	return i915_wait_request(request,
+				 I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
+				 NULL, NULL);
 }
 
 /**
@@ -639,7 +642,9 @@ i915_gem_active_retire(struct i915_gem_active *active,
 	if (!request)
 		return 0;
 
-	ret = i915_wait_request(request, I915_WAIT_INTERRUPTIBLE, NULL, NULL);
+	ret = i915_wait_request(request,
+				I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
+				NULL, NULL);
 	if (ret)
 		return ret;