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From: Vincent Whitchurch <vincent.whitchurch@axis.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Jie Deng <jie.deng@intel.com>, "wsa@kernel.org" <wsa@kernel.org>,
	"virtualization@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>,
	"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	kernel <kernel@axis.com>
Subject: Re: [PATCH 2/2] i2c: virtio: fix completion handling
Date: Fri, 29 Oct 2021 13:54:46 +0200	[thread overview]
Message-ID: <20211029115446.GA24060@axis.com> (raw)
In-Reply-To: <20211020104709.k6oqo2gmegiwfre4@vireshk-i7>

On Wed, Oct 20, 2021 at 12:47:09PM +0200, Viresh Kumar wrote:
> On 20-10-21, 12:38, Vincent Whitchurch wrote:
> > I don't quite understand how that would be safe since
> > virtqueue_add_sgs() can fail after a few iterations and all queued
> > request buffers can have FAIL_NEXT set.  In such a case, we would end up
> > waiting forever with your proposed change, wouldn't we?
> 
> Good point. I didn't think of that earlier.
> 
> I think a good simple way of handling this is counting the number of
> buffers sent and received. Once they match, we are done. That
> shouldn't break anything else I believe.

That could work, but it's not so straightforward since you would have to
introduce locking to prevent races since the final count is only known
after virtio_i2c_prepare_reqs() completes, while the callback could be
called before that.  Please do not hesitate to send out a patch to fix
it that way if that is what you prefer.

  reply	other threads:[~2021-10-29 11:54 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-19  7:46 [PATCH 0/2] virtio-i2c: Fix buffer handling Vincent Whitchurch
2021-10-19  7:46 ` [PATCH 1/2] i2c: virtio: disable timeout handling Vincent Whitchurch
2021-10-19  8:09   ` Viresh Kumar
2021-10-19  9:36     ` Greg KH
2021-10-19  9:42       ` Viresh Kumar
2021-10-19 11:15         ` Wolfram Sang
2021-10-19 14:14           ` Viresh Kumar
2021-10-19 11:16         ` Greg KH
2021-10-19 14:37           ` Viresh Kumar
2021-10-19 18:14             ` Wolfram Sang
2021-10-20  4:20               ` Jie Deng
2021-10-20  5:36                 ` Greg KH
2021-10-20  6:35                   ` Jie Deng
2021-10-20  6:41                     ` Viresh Kumar
2021-10-20  7:04                       ` Jie Deng
2021-10-20 10:55                         ` Vincent Whitchurch
2021-10-20 11:03                           ` Viresh Kumar
2021-10-21  3:30                             ` Jie Deng
2021-10-29 12:24                               ` Vincent Whitchurch
2021-11-01  5:23                                 ` Jie Deng
2021-11-03  6:18                                   ` Chen, Conghui
2021-11-03  6:37                                     ` Viresh Kumar
2021-11-03 14:42                                       ` Vincent Whitchurch
2021-11-09  4:52                                         ` Viresh Kumar
2021-10-20  3:36     ` Jie Deng
2021-10-19  7:46 ` [PATCH 2/2] i2c: virtio: fix completion handling Vincent Whitchurch
2021-10-19  8:22   ` Viresh Kumar
2021-10-20  8:54     ` Jie Deng
2021-10-20  9:17       ` Viresh Kumar
2021-10-20 10:38         ` Vincent Whitchurch
2021-10-20 10:47           ` Viresh Kumar
2021-10-29 11:54             ` Vincent Whitchurch [this message]
2021-10-21  5:55   ` Jie Deng
2021-10-21  5:58     ` Viresh Kumar
2021-11-02  4:32   ` Viresh Kumar

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