[RFC v2 12/13] drm/i915: Protect access to driver and timeline name

[Tvrtko Ursulin]

Protect the access to driver and timeline name which otherwise could be
freed as dma-fence exported is signalling fences.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com>
---
 drivers/gpu/drm/i915/gt/intel_gt_requests.c | 2 ++
 drivers/gpu/drm/i915/i915_request.c         | 5 +++--
 drivers/gpu/drm/i915/i915_sw_fence.c        | 2 ++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c 
b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
index ae3557ed6c1e..11fca24c8b5b 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
@@ -251,10 +251,12 @@ void intel_gt_watchdog_work(struct work_struct *work)
                if (!i915_request_completed(rq)) {
                        struct dma_fence *f = &rq->fence;
 
+                       dma_fence_access_begin();
                        pr_notice("Fence expiration time out 
i915-%s:%s:%llx!\n",
                                  dma_fence_driver_name(f),
                                  dma_fence_timeline_name(f),
                                  f->seqno);
+                       dma_fence_access_end();
                        i915_request_cancel(rq, -EINTR);
                }
                i915_request_put(rq);
diff --git a/drivers/gpu/drm/i915/i915_request.c 
b/drivers/gpu/drm/i915/i915_request.c
index 4874c4f1e4ab..8008b7767641 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -2184,7 +2184,6 @@ void i915_request_show(struct drm_printer *m,
                       const char *prefix,
                       int indent)
 {
-       const char *name = dma_fence_timeline_name((struct dma_fence 
*)&rq->fence);
        char buf[80] = "";
        int x = 0;
 
@@ -2220,6 +2219,7 @@ void i915_request_show(struct drm_printer *m,
 
        x = print_sched_attr(&rq->sched.attr, buf, x, sizeof(buf));
 
+       dma_fence_access_begin();
        drm_printf(m, "%s%.*s%c %llx:%lld%s%s %s @ %dms: %s\n",
                   prefix, indent, "                ",
                   queue_status(rq),
@@ -2228,7 +2228,8 @@ void i915_request_show(struct drm_printer *m,
                   fence_status(rq),
                   buf,
                   jiffies_to_msecs(jiffies - rq->emitted_jiffies),
-                  name);
+                  dma_fence_timeline_name((struct dma_fence *)&rq->fence));
+       dma_fence_access_end();
 }
 
 static bool engine_match_ring(struct intel_engine_cs *engine, struct 
i915_request *rq)
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c 
b/drivers/gpu/drm/i915/i915_sw_fence.c
index e51ca7e50a4e..e7bdc1165b90 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -434,11 +434,13 @@ static void timer_i915_sw_fence_wake(struct timer_list *t)
        if (!fence)
                return;
 
+       dma_fence_access_begin();
        pr_notice("Asynchronous wait on fence %s:%s:%llx timed out 
(hint:%ps)\n",
                  dma_fence_driver_name(cb->dma),
                  dma_fence_timeline_name(cb->dma),
                  cb->dma->seqno,
                  i915_sw_fence_debug_hint(fence));
+       dma_fence_access_end();
 
        i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
        i915_sw_fence_complete(fence);
-- 
2.48.0