drm/i915/selftests: Take a ref to the request we wait upon

i915_request_add() consumes the passed in reference to the i915_request,
so if the selftest caller wishes to wait upon it afterwards, it needs to
take a reference for itself.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191120102741.3734346-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
index 9a509c1..f1ce5f6 100644 (file)
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
@@ -73,25 +73,34 @@ static int live_nop_switch(void *arg)
        }
 
        for_each_uabi_engine(engine, i915) {
-               struct i915_request *rq;
+               struct i915_request *rq = NULL;
                unsigned long end_time, prime;
                ktime_t times[2] = {};
 
                times[0] = ktime_get_raw();
                for (n = 0; n < nctx; n++) {
-                       rq = igt_request_alloc(ctx[n], engine);
-                       if (IS_ERR(rq)) {
-                               err = PTR_ERR(rq);
+                       struct i915_request *this;
+
+                       this = igt_request_alloc(ctx[n], engine);
+                       if (IS_ERR(this)) {
+                               err = PTR_ERR(this);
                                goto out_file;
                        }
-                       i915_request_add(rq);
+                       if (rq) {
+                               i915_request_await_dma_fence(this, &rq->fence);
+                               i915_request_put(rq);
+                       }
+                       rq = i915_request_get(this);
+                       i915_request_add(this);
                }
                if (i915_request_wait(rq, 0, HZ / 5) < 0) {
                        pr_err("Failed to populated %d contexts\n", nctx);
                        intel_gt_set_wedged(&i915->gt);
+                       i915_request_put(rq);
                        err = -EIO;
                        goto out_file;
                }
+               i915_request_put(rq);
 
                times[1] = ktime_get_raw();
 
@@ -106,13 +115,21 @@ static int live_nop_switch(void *arg)
                for_each_prime_number_from(prime, 2, 8192) {
                        times[1] = ktime_get_raw();
 
+                       rq = NULL;
                        for (n = 0; n < prime; n++) {
-                               rq = igt_request_alloc(ctx[n % nctx], engine);
-                               if (IS_ERR(rq)) {
-                                       err = PTR_ERR(rq);
+                               struct i915_request *this;
+
+                               this = igt_request_alloc(ctx[n % nctx], engine);
+                               if (IS_ERR(this)) {
+                                       err = PTR_ERR(this);
                                        goto out_file;
                                }
 
+                               if (rq) { /* Force submission order */
+                                       i915_request_await_dma_fence(this, &rq->fence);
+                                       i915_request_put(rq);
+                               }
+
                                /*
                                 * This space is left intentionally blank.
                                 *
@@ -127,14 +144,18 @@ static int live_nop_switch(void *arg)
                                 * for latency.
                                 */
 
-                               i915_request_add(rq);
+                               rq = i915_request_get(this);
+                               i915_request_add(this);
                        }
+                       GEM_BUG_ON(!rq);
                        if (i915_request_wait(rq, 0, HZ / 5) < 0) {
                                pr_err("Switching between %ld contexts timed out\n",
                                       prime);
                                intel_gt_set_wedged(&i915->gt);
+                               i915_request_put(rq);
                                break;
                        }
+                       i915_request_put(rq);
 
                        times[1] = ktime_sub(ktime_get_raw(), times[1]);
                        if (prime == 2)