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Subject: Re: [REPOST PATCH 1/8] fence: dma-buf cross-device synchronization (v17)
From: Daniel Vetter <daniel@ffwll.ch>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Rob Clark <robdclark@gmail.com>,
        Maarten Lankhorst <maarten.lankhorst@canonical.com>,
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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. Except when you can
prove that the kernel will die in the next few lines and there's
nothing you can do about it a WARN_ON is always better - I've wasted
_way_ too much time debugging hard hangs because such a "benign"
BUG_ON ended up eating my irq handler or a spinlock required by such.
Or some other nonsense that makes debugging a royal pita, especially
if your remote debugger consists of a frustrated users staring at a
hung machine.

</rant>

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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