From: Peter Zijlstra <peterz@infradead.org>
To: "Christian König" <christian.koenig@amd.com>
Cc: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] locking/ww_mutex: cleanup lock->ctx usage in amdgpu
Date: Tue, 20 Feb 2018 14:22:54 +0100 [thread overview]
Message-ID: <20180220132254.GB25201@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <c22fe062-6c7e-cfa3-5f0b-da135a751921@amd.com>
On Tue, Feb 20, 2018 at 02:08:26PM +0100, Christian König wrote:
> Am 20.02.2018 um 13:35 schrieb Peter Zijlstra:
> > > +static inline bool ww_mutex_is_owned_by(struct ww_mutex *lock,
> > > + struct task_struct *task,
> > > + struct ww_acquire_ctx *ctx)
> > > +{
> > > + return likely(__mutex_owner(&lock->base) == task) &&
> > > + READ_ONCE(lock->ctx) == ctx;
> > > +}
> > Nak on that interface, that's racy and broken by design.
>
> Why?
If task != current you can race with a concurrent mutex_unlock().
prev parent reply other threads:[~2018-02-20 13:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-15 14:19 [PATCH 1/3] locking/ww_mutex: cleanup lock->ctx usage in amdgpu Christian König
2018-02-15 14:19 ` [PATCH 2/3] drm/ttm: handle already locked BOs during eviction and swapout Christian König
2018-02-15 14:19 ` [PATCH 3/3] drm/ttm: keep BOs reserved until end of eviction Christian König
2018-02-15 20:36 ` [PATCH 1/3] locking/ww_mutex: cleanup lock->ctx usage in amdgpu Alex Deucher
2018-02-19 15:24 ` Daniel Vetter
2018-02-19 15:41 ` Christian König
2018-02-19 16:15 ` Daniel Vetter
2018-02-19 16:29 ` Christian König
2018-02-19 16:43 ` Daniel Vetter
2018-02-20 9:43 ` Christian König
2018-02-20 11:33 ` Daniel Vetter
2018-02-20 12:31 ` Christian König
2018-02-20 12:35 ` Peter Zijlstra
2018-02-20 13:08 ` Christian König
2018-02-20 13:22 ` Peter Zijlstra [this message]
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