From: Peter Zijlstra <peterz@infradead.org>
To: "Christian König" <ckoenig.leichtzumerken@gmail.com>
Cc: daniel@ffwll.ch, mingo@redhat.com, will@kernel.org,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/syncobj: make lockdep complain on WAIT_FOR_SUBMIT v2
Date: Tue, 19 Jan 2021 10:35:38 +0100 [thread overview]
Message-ID: <YAan6haGjnIlNIoJ@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210118180334.43714-2-christian.koenig@amd.com>
On Mon, Jan 18, 2021 at 07:03:34PM +0100, Christian König wrote:
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 6e74e6745eca..f51458615158 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -387,6 +387,13 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
> if (!syncobj)
> return -ENOENT;
>
> + /* Waiting for userspace with locks help is illegal cause that can
> + * trivial deadlock with page faults for example. Make lockdep complain
> + * about it early on.
> + */
Egads, the cursed comment style is spreading :/
> + if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT)
> + lockdep_assert_none_held_once();
> +
Should this not be part of drm_syncobj_fence_add_wait() instead? Also,
do you want to sprinkle might_sleep() around ?
> *fence = drm_syncobj_fence_get(syncobj);
> drm_syncobj_put(syncobj);
>
> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
next prev parent reply other threads:[~2021-01-19 9:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-18 18:03 Let lockdep complain when locks are taken while waiting for userspace Christian König
2021-01-18 18:03 ` [PATCH] drm/syncobj: make lockdep complain on WAIT_FOR_SUBMIT v2 Christian König
2021-01-18 19:42 ` Randy Dunlap
2021-01-19 9:35 ` Peter Zijlstra [this message]
2021-01-19 9:46 ` Christian König
2021-01-19 10:05 ` Peter Zijlstra
2021-01-19 10:08 ` Christian König
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