Protect the access to driver and timeline name which otherwise could be
freed as dma-fence exported is signalling fences.
This prepares the code for incoming dma-fence API changes which will start
asserting these accesses are done from a RCU locked section.
Now that the safe access is handled in the dma-fence API, the external
callers such as sync_file, and our internal code paths, we can drop the
similar protection from i915_fence_get_timeline_name().
This prepares the code for incoming dma-fence API changes which will start
asserting these accesses are done from a RCU locked section.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com>
Reviewed-by: Andi Shyti <andi.sh...@linux.intel.com> # v1
---
v2:
* Rebased for dma-fence API change.
---
drivers/gpu/drm/i915/gt/intel_gt_requests.c | 10 ++++++++--
drivers/gpu/drm/i915/i915_request.c | 7 +++++--
drivers/gpu/drm/i915/i915_sw_fence.c | 10 ++++++++--
3 files changed, 21 insertions(+), 6 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..93298820bee2 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
@@ -250,11 +250,17 @@ void intel_gt_watchdog_work(struct work_struct *work)
llist_for_each_entry_safe(rq, rn, first, watchdog.link) {
if (!i915_request_completed(rq)) {
struct dma_fence *f = &rq->fence;
+ const char __rcu *timeline;
+ const char __rcu *driver;
+ rcu_read_lock();
+ driver = dma_fence_driver_name(f);
+ timeline = dma_fence_timeline_name(f);
pr_notice("Fence expiration time out
i915-%s:%s:%llx!\n",
- dma_fence_driver_name(f),
- dma_fence_timeline_name(f),
+ rcu_dereference(driver),
+ rcu_dereference(timeline),
f->seqno);
+ rcu_read_unlock();
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..b9a2b2194c8f 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -2184,7 +2184,7 @@ 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);
+ const char __rcu *timeline;
char buf[80] = "";
int x = 0;
@@ -2220,6 +2220,8 @@ void i915_request_show(struct drm_printer *m,
x = print_sched_attr(&rq->sched.attr, buf, x, sizeof(buf));
+ rcu_read_lock();
+ timeline = dma_fence_timeline_name((struct dma_fence *)&rq->fence);
drm_printf(m, "%s%.*s%c %llx:%lld%s%s %s @ %dms: %s\n",
prefix, indent, " ",
queue_status(rq),
@@ -2228,7 +2230,8 @@ void i915_request_show(struct drm_printer *m,
fence_status(rq),
buf,
jiffies_to_msecs(jiffies - rq->emitted_jiffies),
- name);
+ rcu_dereference(timeline));
+ rcu_read_unlock();
}
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 9edf659d18db..73e89b168fc3 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -430,16 +430,22 @@ static void timer_i915_sw_fence_wake(struct timer_list *t)
struct i915_sw_dma_fence_cb_timer *cb = timer_container_of(cb, t,
timer);
struct i915_sw_fence *fence;
+ const char __rcu *timeline;
+ const char __rcu *driver;
fence = xchg(&cb->base.fence, NULL);
if (!fence)
return;
+ rcu_read_lock();
+ driver = dma_fence_driver_name(cb->dma);
+ timeline = dma_fence_timeline_name(cb->dma);
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),
+ rcu_dereference(driver),
+ rcu_dereference(timeline),
cb->dma->seqno,
i915_sw_fence_debug_hint(fence));
+ rcu_read_unlock();
i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
i915_sw_fence_complete(fence);
--
2.48.0
