From: Arjan van de Ven <arjan@infradead.org>
To: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: mchehab@infradead.org, linux-kernel@vger.kernel.org,
Al Viro <viro@ftp.linux.org.uk>
Subject: Re: [PATCH] Fix open/close race in saa7134
Date: Mon, 23 Jun 2008 12:53:48 -0700 [thread overview]
Message-ID: <20080623125348.3133b30b@infradead.org> (raw)
In-Reply-To: <20080623192141.GB5593@joi>
On Mon, 23 Jun 2008 21:22:03 +0200
Marcin Slusarz <marcin.slusarz@gmail.com> wrote:
>
> If dev->empress_users could be > 1 then ok - it could break, but it
> can only be 1 or 0. If it's 1 you won't open the device. If it's 0
> you won't reach ts_close.
>
> If you still see the race, please show me the sequence, because I
> don't (of course when decrementing is the last operation of ts_close).
a decrement in C, without locking, is NOT atomic.
It in fact is
"load variable into register"
"increment register value"
"write register to variable"
which the compiler then takes and orders for maximum performance....
--
If you want to reach me at my work email, use arjan@linux.intel.com
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next prev parent reply other threads:[~2008-06-23 19:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-22 17:05 Arjan van de Ven
2008-06-22 17:33 ` Marcin Slusarz
2008-06-22 17:45 ` Mauro Carvalho Chehab
2008-06-22 17:57 ` Arjan van de Ven
2008-06-22 17:58 ` Arjan van de Ven
2008-06-23 18:49 ` Marcin Slusarz
2008-06-23 18:54 ` Arjan van de Ven
2008-06-23 19:22 ` Marcin Slusarz
2008-06-23 19:53 ` Arjan van de Ven [this message]
2008-06-23 20:11 ` Marcin Slusarz
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