On Wed, Nov 20, 2019 at 2:56 AM Daniel Vetter daniel.vetter@ffwll.ch wrote:
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.vetter@intel.com Cc: Rob Clark robdclark@gmail.com Cc: Sean Paul sean@poorly.run Cc: linux-arm-msm@vger.kernel.org Cc: freedreno@lists.freedesktop.org
found a few minutes to take this for a spin and seems fine.. t-b && r-b
BR, -R
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