[PATCH v2 11/14] drm/i915: Replace reset_wait_queue with default_wake_function

Chris Wilson
2017-02-14T09:54:29Z

If we change the wait_queue_t from using the autoremove_wake_function to
the default_wake_function, we no longer have to restore the wait_queue_t
entry on the wait_queue_head_t list after being woken up by it, as we
are unusual in sleeping multiple times on the same wait_queue_t.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem_request.c | 30 +++++++-----------------------
1 file changed, 7 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 56ebb653406d..bd921c4b0100 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -938,16 +938,6 @@ void __i915_add_request(struct drm_i915_gem_request *request, bool flush_caches)
local_bh_enable(); /* Kick the execlists tasklet if just scheduled */
}

-static void reset_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&q->lock, flags);
- if (list_empty(&wait->task_list))
- __add_wait_queue(q, wait);
- spin_unlock_irqrestore(&q->lock, flags);
-}
-
static unsigned long local_clock_us(unsigned int *cpu)
{
unsigned long t;
@@ -1042,8 +1032,8 @@ long i915_wait_request(struct drm_i915_gem_request *req,
const int state = flags & I915_WAIT_INTERRUPTIBLE ?
TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
wait_queue_head_t *errq = &req->i915->gpu_error.wait_queue;
- DEFINE_WAIT(reset);
- DEFINE_WAIT(exec);
+ DEFINE_WAIT_FUNC(reset, default_wake_function);
+ DEFINE_WAIT_FUNC(exec, default_wake_function);
struct intel_wait wait;

might_sleep();
@@ -1062,13 +1052,13 @@ long i915_wait_request(struct drm_i915_gem_request *req,

trace_i915_gem_request_wait_begin(req);

+ add_wait_queue(&req->execute, &exec);
if (flags & I915_WAIT_LOCKED)
add_wait_queue(errq, &reset);

wait.tsk = current;

restart:
- reset_wait_queue(&req->execute, &exec);
wait.seqno = i915_gem_request_global_seqno(req);
if (!wait.seqno) {
do {
@@ -1082,26 +1072,21 @@ long i915_wait_request(struct drm_i915_gem_request *req,
i915_reset_in_progress(&req->i915->gpu_error)) {
__set_current_state(TASK_RUNNING);
i915_reset(req->i915);
- reset_wait_queue(errq, &reset);
continue;
}

if (signal_pending_state(state, current)) {
timeout = -ERESTARTSYS;
- break;
+ goto complete;
}

if (!timeout) {
timeout = -ETIME;
- break;
+ goto complete;
}

timeout = io_schedule_timeout(timeout);
} while (1);
- finish_wait(&req->execute, &exec);
-
- if (timeout < 0)
- goto complete;

GEM_BUG_ON(!wait.seqno);
}
@@ -1161,7 +1146,6 @@ long i915_wait_request(struct drm_i915_gem_request *req,
i915_reset_in_progress(&req->i915->gpu_error)) {
__set_current_state(TASK_RUNNING);
i915_reset(req->i915);
- reset_wait_queue(errq, &reset);
continue;
}

@@ -1176,11 +1160,11 @@ long i915_wait_request(struct drm_i915_gem_request *req,
}

intel_engine_remove_wait(req->engine, &wait);
- __set_current_state(TASK_RUNNING);
-
complete:
+ __set_current_state(TASK_RUNNING);
if (flags & I915_WAIT_LOCKED)
remove_wait_queue(errq, &reset);
+ remove_wait_queue(&req->execute, &exec);
trace_i915_gem_request_wait_end(req);

return timeout;
--
2.11.0