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 <[email protected]> Cc: Joonas Lahtinen <[email protected]> Cc: Rodrigo Vivi <[email protected]> Cc: [email protected] Signed-off-by: Daniel Vetter <[email protected]> --- 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 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
