Commit 2467658e authored by Chris Wilson's avatar Chris Wilson

drm/i915: Introduce i915_gem_active_wait_unlocked()

It is useful to be able to wait on pending rendering without grabbing
the struct_mutex. We can do this by using the i915_gem_active_get_rcu()
primitive to acquire a reference to the pending request without
requiring struct_mutex, just the RCU read lock, and then call
i915_wait_request().

v2: Rebase onto new i915_gem_active_get_unlocked() semantics that take
the RCU read lock on behalf of the caller.
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-1-git-send-email-chris@chris-wilson.co.uk
parent 94558e26
...@@ -568,6 +568,46 @@ i915_gem_active_wait(const struct i915_gem_active *active, struct mutex *mutex) ...@@ -568,6 +568,46 @@ i915_gem_active_wait(const struct i915_gem_active *active, struct mutex *mutex)
return i915_wait_request(request, true, NULL, NULL); return i915_wait_request(request, true, NULL, NULL);
} }
/**
* i915_gem_active_wait_unlocked - waits until the request is completed
* @active - the active request on which to wait
* @interruptible - whether the wait can be woken by a userspace signal
* @timeout - how long to wait at most
* @rps - userspace client to charge for a waitboost
*
* i915_gem_active_wait_unlocked() waits until the request is completed before
* returning, without requiring any locks to be held. Note that it does not
* retire any requests before returning.
*
* This function relies on RCU in order to acquire the reference to the active
* request without holding any locks. See __i915_gem_active_get_rcu() for the
* glory details on how that is managed. Once the reference is acquired, we
* can then wait upon the request, and afterwards release our reference,
* free of any locking.
*
* This function wraps i915_wait_request(), see it for the full details on
* the arguments.
*
* Returns 0 if successful, or a negative error code.
*/
static inline int
i915_gem_active_wait_unlocked(const struct i915_gem_active *active,
bool interruptible,
s64 *timeout,
struct intel_rps_client *rps)
{
struct drm_i915_gem_request *request;
int ret = 0;
request = i915_gem_active_get_unlocked(active);
if (request) {
ret = i915_wait_request(request, interruptible, timeout, rps);
i915_gem_request_put(request);
}
return ret;
}
/** /**
* i915_gem_active_retire - waits until the request is retired * i915_gem_active_retire - waits until the request is retired
* @active - the active request on which to wait * @active - the active request on which to wait
......
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