i915_request_wait is simply our i915-optimized version of
dma_fence_wait. They both use the exact same code. To help lockdep
discovering all the dependencies, annotate it.
v2: We do opportunistic retiring of dma-fences while holding
struct_mutex. The recursion this causes is intentional, and we do have
other paths which (hopefully) do depend upon the struct_mutex. 2nd
option to fix these annotations (and probably even better) would be
creating a dma_fence_signal_opportunistic, which doesnt have the
lockdep annotations. But that also doesn't guarantee that we'll
actually manage to signal fences without depending upon struct_mutex
somewhere, so might as well go with this trick here.
Aside, for non-i915 people: struct_mutex is our bkl. The locking rules
are ... complicated.
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_request.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 71107540581d..0f800b8967a4 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -30,6 +30,10 @@
#include "i915_drv.h"
+static long __i915_request_wait(struct i915_request *rq,
+ unsigned int flags,
+ long timeout);
+
static const char *i915_fence_get_driver_name(struct dma_fence *fence)
{
return "i915";
@@ -66,7 +70,7 @@ static signed long i915_fence_wait(struct dma_fence *fence,
bool interruptible,
signed long timeout)
{
- return i915_request_wait(to_request(fence), interruptible, timeout);
+ return __i915_request_wait(to_request(fence), interruptible, timeout);
}
static void i915_fence_release(struct dma_fence *fence)
@@ -1201,6 +1205,21 @@ static bool __i915_wait_request_check_and_reset(struct i915_request *request)
long i915_request_wait(struct i915_request *rq,
unsigned int flags,
long timeout)
+{
+ long ret;
+
+ if (!lockdep_is_held(&rq->i915->drm.struct_mutex))
+ dma_fence_wait_acquire();
+ ret = __i915_request_wait(rq, flags, timeout);
+ if (!lockdep_is_held(&rq->i915->drm.struct_mutex))
+ dma_fence_wait_release();
+
+ return ret;
+}
+
+static long __i915_request_wait(struct i915_request *rq,
+ unsigned int flags,
+ long timeout)
{
const int state = flags & I915_WAIT_INTERRUPTIBLE ?
TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
--
2.19.1
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