From: Stefani Seibold <stefani@seibold.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Walls <awalls@radix.net>,
Mauro Carvalho Chehab <mchehab@infradead.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [Fwd: [patch] media video cx23888 driver: ported to new kfifo API]
Date: Fri, 18 Dec 2009 23:09:26 +0100 [thread overview]
Message-ID: <1261174166.13019.20.camel@wall-e> (raw)
In-Reply-To: <20091218140026.15416033.akpm@linux-foundation.org>
Am Freitag, den 18.12.2009, 14:00 -0800 schrieb Andrew Morton:
> On Fri, 18 Dec 2009 22:57:22 +0100
> Stefani Seibold <stefani@seibold.net> wrote:
>
> > But kfifo_len() did not
> > requiere a lock in my opinion. It is save to use without a look.
>
> What do you mean by this? Safe in general, or safe in this particular driver?
>
Safe until you don't call kfifo_reset(). kfifo_reset() is evil, because
it it the only function which breaks the single read/writer concept.
This function modifies the in and the out fifo counters. Thats why i
introduced the kfifo_reset_out() function, which set the out to the
value of in, which means the fifo is empty. This function can be call
from the receiver of a fifo without locking.
Stefani
prev parent reply other threads:[~2009-12-18 22:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-18 10:14 [Fwd: [patch] media video cx23888 driver: ported to new kfifo API] Mauro Carvalho Chehab
2009-12-18 12:00 ` Andy Walls
2009-12-18 12:11 ` Stefani Seibold
2009-12-18 21:39 ` Andy Walls
2009-12-18 21:57 ` Stefani Seibold
2009-12-18 22:00 ` Andrew Morton
2009-12-18 22:09 ` Stefani Seibold [this message]
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