| Message ID | 20191119210844.16947-4-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | more dma-buf lockdep priming | expand |
On Tue, Nov 19, 2019 at 1:08 PM 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. seems reasonable.. but maybe a comment would be useful to prevent future-me from "cleaning-this-up" back to the way it was with that, r-b > > Aside: Why is msm still using struct_mutex, it seems to be using > dma_resv_lock for general buffer state protection? only because I (or anyone else) hasn't had time to revisit the struct_mutex usage since we moved to per-object-locks.. the downside, I suppose, of kernel generally working ok and this not being a big enough fire to bubble up to the top of my todo list BR, -R > > 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 > --- > drivers/gpu/drm/msm/msm_gem_submit.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c > index fb1fdd7fa3ef..126b2f62bfe7 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; > } > @@ -489,6 +488,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, > if (ret) > goto out; > > + ww_acquire_init(&submit->ticket, &reservation_ww_class); > ret = submit_lock_objects(submit); > if (ret) > goto out; > -- > 2.24.0 >
On Wed, Nov 20, 2019 at 3:07 AM Rob Clark <robdclark@gmail.com> wrote: > > On Tue, Nov 19, 2019 at 1:08 PM 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. > > seems reasonable.. but maybe a comment would be useful to prevent > future-me from "cleaning-this-up" back to the way it was I'll add a comment. > with that, r-b Well I spotted a bug for the error handling, I'll need to respin. -Daniel > > > > > Aside: Why is msm still using struct_mutex, it seems to be using > > dma_resv_lock for general buffer state protection? > > only because I (or anyone else) hasn't had time to revisit the > struct_mutex usage since we moved to per-object-locks.. the downside, > I suppose, of kernel generally working ok and this not being a big > enough fire to bubble up to the top of my todo list > > BR, > -R > > > > > 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 > > --- > > drivers/gpu/drm/msm/msm_gem_submit.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c > > index fb1fdd7fa3ef..126b2f62bfe7 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; > > } > > @@ -489,6 +488,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, > > if (ret) > > goto out; > > > > + ww_acquire_init(&submit->ticket, &reservation_ww_class); > > ret = submit_lock_objects(submit); > > if (ret) > > goto out; > > -- > > 2.24.0 > >
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c index fb1fdd7fa3ef..126b2f62bfe7 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; } @@ -489,6 +488,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, if (ret) goto out; + ww_acquire_init(&submit->ticket, &reservation_ww_class); ret = submit_lock_objects(submit); if (ret) goto out;
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? 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 --- drivers/gpu/drm/msm/msm_gem_submit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)