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From: Greg KH <gregkh@linuxfoundation.org>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: linux-arch@vger.kernel.org,
	Thomas Hellstrom <thellstrom@vmware.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linaro-mm-sig@lists.linaro.org" <linaro-mm-sig@lists.linaro.org>,
	Colin Cross <ccross@google.com>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
Subject: Re: [REPOST PATCH 1/8] fence: dma-buf cross-device synchronization (v17)
Date: Thu, 19 Jun 2014 13:01:59 -0700	[thread overview]
Message-ID: <20140619200159.GA27883@kroah.com> (raw)
In-Reply-To: <CAKMK7uFa57YjeJCFQhWFr_5cRTTpWxBdJ1qtb5Ojnu-KZpe-Lw@mail.gmail.com>

On Thu, Jun 19, 2014 at 09:15:36PM +0200, Daniel Vetter wrote:
> On Thu, Jun 19, 2014 at 7:00 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >> >> +     BUG_ON(f1->context != f2->context);
> >> >
> >> > Nice, you just crashed the kernel, making it impossible to debug or
> >> > recover :(
> >>
> >> agreed, that should probably be 'if (WARN_ON(...)) return NULL;'
> >>
> >> (but at least I wouldn't expect to hit that under console_lock so you
> >> should at least see the last N lines of the backtrace on the screen
> >> ;-))
> >
> > Lots of devices don't have console screens :)
> 
> Aside: This is a pet peeve of mine and recently I've switched to
> rejecting all patch that have a BUG_ON, period.

Please do, I have been for a few years now as well for the same reasons
you cite.

greg k-h

WARNING: multiple messages have this Message-ID (diff)
From: Greg KH <gregkh@linuxfoundation.org>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Rob Clark <robdclark@gmail.com>,
	Maarten Lankhorst <maarten.lankhorst@canonical.com>,
	linux-arch@vger.kernel.org,
	Thomas Hellstrom <thellstrom@vmware.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linaro-mm-sig@lists.linaro.org" <linaro-mm-sig@lists.linaro.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Colin Cross <ccross@google.com>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
Subject: Re: [REPOST PATCH 1/8] fence: dma-buf cross-device synchronization (v17)
Date: Thu, 19 Jun 2014 13:01:59 -0700	[thread overview]
Message-ID: <20140619200159.GA27883@kroah.com> (raw)
Message-ID: <20140619200159.7F7jcPjhmB_QAP1FbRA0WDuE-Y8TiqgEkyPSb2kLLk8@z> (raw)
In-Reply-To: <CAKMK7uFa57YjeJCFQhWFr_5cRTTpWxBdJ1qtb5Ojnu-KZpe-Lw@mail.gmail.com>

On Thu, Jun 19, 2014 at 09:15:36PM +0200, Daniel Vetter wrote:
> On Thu, Jun 19, 2014 at 7:00 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >> >> +     BUG_ON(f1->context != f2->context);
> >> >
> >> > Nice, you just crashed the kernel, making it impossible to debug or
> >> > recover :(
> >>
> >> agreed, that should probably be 'if (WARN_ON(...)) return NULL;'
> >>
> >> (but at least I wouldn't expect to hit that under console_lock so you
> >> should at least see the last N lines of the backtrace on the screen
> >> ;-))
> >
> > Lots of devices don't have console screens :)
> 
> Aside: This is a pet peeve of mine and recently I've switched to
> rejecting all patch that have a BUG_ON, period.

Please do, I have been for a few years now as well for the same reasons
you cite.

greg k-h

  parent reply	other threads:[~2014-06-19 20:01 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-18 10:36 [REPOST PATCH 0/8] fence synchronization patches Maarten Lankhorst
2014-06-18 10:36 ` Maarten Lankhorst
2014-06-18 10:36 ` [REPOST PATCH 1/8] fence: dma-buf cross-device synchronization (v17) Maarten Lankhorst
2014-06-18 10:36   ` Maarten Lankhorst
2014-06-19  1:13   ` Greg KH
2014-06-19  1:13     ` Greg KH
2014-06-19  1:23     ` Rob Clark
2014-06-19  1:23       ` Rob Clark
2014-06-19  1:44       ` Greg KH
2014-06-19  1:44         ` Greg KH
2014-06-19 14:00     ` Rob Clark
2014-06-19 17:00       ` Greg KH
2014-06-19 17:00         ` Greg KH
2014-06-19 17:45         ` Rob Clark
2014-06-19 17:45           ` Rob Clark
2014-06-19 18:19           ` Greg KH
2014-06-19 18:37             ` James Bottomley
2014-06-19 18:37               ` James Bottomley
2014-06-19 18:52             ` Rob Clark
2014-06-19 18:52               ` Rob Clark
2014-06-19 19:20             ` Daniel Vetter
2014-06-19 19:20               ` Daniel Vetter
2014-06-19 21:50             ` Dave Airlie
2014-06-19 21:50               ` Dave Airlie
2014-06-19 23:21               ` Rob Clark
2014-06-19 23:21                 ` Rob Clark
2014-06-19 19:15         ` Daniel Vetter
2014-06-19 19:15           ` Daniel Vetter
2014-06-19 20:01           ` Greg KH [this message]
2014-06-19 20:01             ` Greg KH
2014-06-19 22:39             ` H. Peter Anvin
2014-06-19 22:39               ` H. Peter Anvin
2014-06-19 23:08               ` James Bottomley
2014-06-19 23:08                 ` James Bottomley
2014-06-19 23:42               ` Greg KH
2014-06-20  8:30                 ` Daniel Vetter
2014-06-20  8:24               ` Daniel Vetter
2014-06-20  8:24                 ` Daniel Vetter
2014-06-19  1:15   ` Greg KH
2014-06-19  1:16   ` Greg KH
2014-06-19  1:25     ` Rob Clark
2014-06-19  1:25       ` Rob Clark
2014-06-19  4:27       ` Sumit Semwal
2014-06-19  4:54         ` Greg KH
2014-06-19  4:54           ` Greg KH
2014-06-19  5:26           ` Sumit Semwal
2014-06-19  5:26             ` Sumit Semwal
2014-06-18 10:37 ` [REPOST PATCH 2/8] seqno-fence: Hardware dma-buf implementation of fencing (v5) Maarten Lankhorst
2014-06-18 10:37   ` Maarten Lankhorst
2014-06-18 10:37 ` [REPOST PATCH 3/8] dma-buf: use reservation objects Maarten Lankhorst
2014-06-18 10:37   ` Maarten Lankhorst
2014-06-18 10:37 ` [REPOST PATCH 4/8] android: convert sync to fence api, v5 Maarten Lankhorst
2014-06-18 10:37   ` Maarten Lankhorst
2014-06-19  1:15   ` Greg KH
2014-06-19  6:37     ` Daniel Vetter
2014-06-19  6:37       ` Daniel Vetter
2014-06-19 11:48       ` Thierry Reding
2014-06-19 11:48         ` Thierry Reding
2014-06-19 12:28         ` Daniel Vetter
2014-06-19 15:35           ` Colin Cross
2014-06-19 16:34             ` Daniel Vetter
2014-06-19 16:34               ` Daniel Vetter
2014-06-20 20:52           ` Thierry Reding
2014-06-20 20:52             ` Thierry Reding
2014-06-23  8:45             ` Maarten Lankhorst
2014-07-07 13:28               ` Daniel Vetter
2014-07-07 13:28                 ` Daniel Vetter
2014-06-19 15:22       ` Colin Cross
2014-06-19 15:22         ` Colin Cross
2014-06-19 16:12         ` Maarten Lankhorst
2014-06-18 10:37 ` [REPOST PATCH 5/8] reservation: add support for fences to enable cross-device synchronisation Maarten Lankhorst
2014-06-18 10:37   ` Maarten Lankhorst
2014-06-18 10:37 ` [REPOST PATCH 6/8] dma-buf: add poll support, v3 Maarten Lankhorst
2014-06-18 10:37   ` Maarten Lankhorst
2014-06-18 10:37 ` [REPOST PATCH 7/8] reservation: update api and add some helpers Maarten Lankhorst
2014-06-18 10:37   ` Maarten Lankhorst
2014-06-18 10:37 ` [REPOST PATCH 8/8] reservation: add suppport for read-only access using rcu Maarten Lankhorst
2014-06-18 10:37   ` Maarten Lankhorst
  -- strict thread matches above, loose matches on Subject: below --
2014-06-19 17:53 [REPOST PATCH 1/8] fence: dma-buf cross-device synchronization (v17) Eric Boxer

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