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From: Vaishali Thakkar <vaishali.thakkar@oracle.com>
To: Rob Clark <robdclark@gmail.com>, David Airlie <airlied@linux.ie>,
	linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	Julia Lawall <julia.lawall@lip6.fr>
Subject: Use of copy_from_user in msm_gem_submit.c while holding a spin_lock
Date: Wed, 17 Aug 2016 17:10:30 +0530	[thread overview]
Message-ID: <57B44D2E.2030301@oracle.com> (raw)

Hello,

I was wondering about the call to copy_from_user in function submit_lookup_objects for drive
/gpu/drm/msm/msm_gem_submit.c  It calls copy_from_user[1] in a spin_lock, which is not normally
allowed, due to the possibility of a deadlock.  

Is there some reason that I am overlooking why it is OK in this case? Is there some code in the
same file which ensures that page fault will not occur when we are calling the function holding
spin_lock?

Thank you.

[1] http://lxr.free-electrons.com/source/drivers/gpu/drm/msm/msm_gem_submit.c#L85

-- 
Vaishali
_______________________________________________
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dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: Vaishali Thakkar <vaishali.thakkar@oracle.com>
To: Rob Clark <robdclark@gmail.com>, David Airlie <airlied@linux.ie>,
	linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	Julia Lawall <julia.lawall@lip6.fr>
Subject: Use of copy_from_user in msm_gem_submit.c while holding a spin_lock
Date: Wed, 17 Aug 2016 17:10:30 +0530	[thread overview]
Message-ID: <57B44D2E.2030301@oracle.com> (raw)

Hello,

I was wondering about the call to copy_from_user in function submit_lookup_objects for drive
/gpu/drm/msm/msm_gem_submit.c  It calls copy_from_user[1] in a spin_lock, which is not normally
allowed, due to the possibility of a deadlock.  

Is there some reason that I am overlooking why it is OK in this case? Is there some code in the
same file which ensures that page fault will not occur when we are calling the function holding
spin_lock?

Thank you.

[1] http://lxr.free-electrons.com/source/drivers/gpu/drm/msm/msm_gem_submit.c#L85

-- 
Vaishali

             reply	other threads:[~2016-08-17 11:40 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-17 11:40 Vaishali Thakkar [this message]
2016-08-17 11:40 ` Use of copy_from_user in msm_gem_submit.c while holding a spin_lock Vaishali Thakkar
     [not found] ` <57B44D2E.2030301-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2016-08-17 15:08   ` Rob Clark
2016-08-17 15:08     ` Rob Clark
2016-08-17 17:08     ` Al Viro
     [not found]       ` <20160817170827.GC2356-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2016-08-17 18:49         ` Rob Clark
2016-08-17 18:49           ` Rob Clark
     [not found]           ` <CAF6AEGtLVW-_PMhpb5YQX_vXfn5t=jH7Fe7R+1DbMaoWt6Cc1A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-08-17 18:58             ` Rob Clark
2016-08-17 18:58               ` Rob Clark
2016-08-17 19:15             ` Al Viro
2016-08-17 19:15               ` Al Viro
2016-08-17 19:24               ` Rob Clark
2016-08-17 19:31                 ` Al Viro
2016-08-18  8:31                   ` Daniel Vetter
2016-08-18  8:31                     ` Daniel Vetter
2016-08-17 21:29               ` Rob Clark
2016-08-17 21:29                 ` Rob Clark
     [not found]                 ` <CAF6AEGsJ0scrJp_4Udh2PTxwZq6_poRZuDQYHF6UayFb1htT5Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-08-18  8:36                   ` Daniel Vetter
2016-08-18  8:36                     ` Daniel Vetter
2016-08-18 10:55                     ` Rob Clark
2016-08-18 10:55                       ` Rob Clark
2016-08-18 13:08                       ` Daniel Vetter
2016-08-18 13:08                         ` Daniel Vetter
2016-08-18 13:14                         ` Rob Clark
2016-08-18 13:14                           ` Rob Clark

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