Re: [Intel-gfx] [PATCH v4 3/5] drm/i915: Create the locked version of the request create

[Das, Nirmoy]

On 3/8/2023 10:41 AM, Andi Shyti wrote:

Make version of the request creation that doesn't hold any
lock.

Signed-off-by: Andi Shyti <andi.sh...@linux.intel.com>
Cc: sta...@vger.kernel.org

Reviewed-by: Nirmoy Das <nirmoy....@intel.com>

---
  drivers/gpu/drm/i915/i915_request.c | 43 +++++++++++++++++++----------
  drivers/gpu/drm/i915/i915_request.h |  2 ++
  2 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c 
b/drivers/gpu/drm/i915/i915_request.c
index 72aed544f8714..5ddb0e02b06b7 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1028,18 +1028,11 @@ __i915_request_create(struct intel_context *ce, gfp_t 
gfp)
        return ERR_PTR(ret);
  }

-struct i915_request *

-i915_request_create(struct intel_context *ce)
+static struct i915_request *
+__i915_request_create_locked(struct intel_context *ce)
  {
        struct i915_request *rq;
-       struct intel_timeline *tl;
-
-       if (intel_context_throttle(ce))
-               return ERR_PTR(-EINTR);
-
-       tl = intel_context_timeline_lock(ce);
-       if (IS_ERR(tl))
-               return ERR_CAST(tl);
+       struct intel_timeline *tl = ce->timeline;

/* Move our oldest request to the slab-cache (if not in use!) */

        rq = list_first_entry(&tl->requests, typeof(*rq), link);
@@ -1049,16 +1042,38 @@ i915_request_create(struct intel_context *ce)
        intel_context_enter(ce);
        rq = __i915_request_create(ce, GFP_KERNEL);
        intel_context_exit(ce); /* active reference transferred to request */
-       if (IS_ERR(rq))
-               goto err_unlock;

/* Check that we do not interrupt ourselves with a new request */

        rq->cookie = lockdep_pin_lock(&tl->mutex);

return rq;

+}
+
+struct i915_request *
+i915_request_create_locked(struct intel_context *ce)
+{
+       intel_context_assert_timeline_is_locked(ce->timeline);
+
+       if (intel_context_throttle(ce))
+               return ERR_PTR(-EINTR);
+
+       return __i915_request_create_locked(ce);
+}
+
+struct i915_request *
+i915_request_create(struct intel_context *ce)
+{
+       struct i915_request *rq;
+       struct intel_timeline *tl;
+
+       tl = intel_context_timeline_lock(ce);
+       if (IS_ERR(tl))
+               return ERR_CAST(tl);
+
+       rq = __i915_request_create_locked(ce);
+       if (IS_ERR(rq))
+               intel_context_timeline_unlock(tl);

-err_unlock:

-       intel_context_timeline_unlock(tl);
        return rq;
  }

diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h

index f5e1bb5e857aa..bb48bd4605c03 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -374,6 +374,8 @@ struct i915_request * __must_check
  __i915_request_create(struct intel_context *ce, gfp_t gfp);
  struct i915_request * __must_check
  i915_request_create(struct intel_context *ce);
+struct i915_request * __must_check
+i915_request_create_locked(struct intel_context *ce);

void __i915_request_skip(struct i915_request *rq);

  bool i915_request_set_error_once(struct i915_request *rq, int error);