For locking semantics it really doesn't matter when we grab the
ticket. But for lockdep validation it does: the acquire ctx is a fake
lockdep. Since other drivers might want to do a full multi-lock dance
in their fault-handler, not just lock a single dma_resv. Therefore we
must init the acquire_ctx only after we've done all the copy_*_user or
anything else that might trigger a pagefault. For msm this means we
need to move it past submit_lookup_objects.
Aside: Why is msm still using struct_mutex, it seems to be using
dma_resv_lock for general buffer state protection?
v2:
- Add comment to explain why the ww ticket setup is separate (Rob)
- Fix up error handling, we need to make sure we don't call
ww_acquire_fini without _init.
Signed-off-by: Daniel Vetter <daniel.vet...@intel.com>
Cc: Rob Clark <robdcl...@gmail.com>
Cc: Sean Paul <s...@poorly.run>
Cc: linux-arm-...@vger.kernel.org
Cc: freedr...@lists.freedesktop.org
---
drivers/gpu/drm/msm/msm_gem_submit.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c
b/drivers/gpu/drm/msm/msm_gem_submit.c
index fb1fdd7fa3ef..385d4965a8d0 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -54,7 +54,6 @@ static struct msm_gem_submit *submit_create(struct drm_device
*dev,
INIT_LIST_HEAD(&submit->node);
INIT_LIST_HEAD(&submit->bo_list);
- ww_acquire_init(&submit->ticket, &reservation_ww_class);
return submit;
}
@@ -390,8 +389,6 @@ static void submit_cleanup(struct msm_gem_submit *submit)
list_del_init(&msm_obj->submit_entry);
drm_gem_object_put(&msm_obj->base);
}
-
- ww_acquire_fini(&submit->ticket);
}
int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
@@ -408,6 +405,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
struct msm_ringbuffer *ring;
int out_fence_fd = -1;
struct pid *pid = get_pid(task_pid(current));
+ bool has_ww_ticket = false;
unsigned i;
int ret, submitid;
if (!gpu)
@@ -489,6 +487,9 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
if (ret)
goto out;
+ /* copy_*_user while holding a ww ticket upsets lockdep */
+ ww_acquire_init(&submit->ticket, &reservation_ww_class);
+ has_ww_ticket = true;
ret = submit_lock_objects(submit);
if (ret)
goto out;
@@ -588,6 +589,8 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
out:
submit_cleanup(submit);
+ if (has_ww_ticket)
+ ww_acquire_fini(&submit->ticket);
if (ret)
msm_gem_submit_free(submit);
out_unlock:
--
2.24.0
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
