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From: Rusty Russell <rusty@rustcorp.com.au>
To: Amit Shah <amit.shah@redhat.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Virtualization List <virtualization@lists.linux-foundation.org>
Subject: Re: [PATCH 1/2] virtio: console: Fix poll blocking even though there is data to read
Date: Mon, 20 Sep 2010 12:19:33 +0930	[thread overview]
Message-ID: <201009201219.34378.rusty@rustcorp.com.au> (raw)
In-Reply-To: <6c7c2590a114d65ec52689be7cda7ada5ee876d5.1284628364.git.amit.shah@redhat.com>

On Thu, 16 Sep 2010 06:43:08 pm Amit Shah wrote:
> From: Hans de Goede <hdegoede@redhat.com>
> 
> I found this while working on a Linux agent for spice, the symptom I was
> seeing was select blocking on the spice vdagent virtio serial port even
> though there were messages queued up there.
> 
> virtio_console's port_fops_poll checks port->inbuf != NULL to determine
> if read won't block. However if an application reads enough bytes from
> inbuf through port_fops_read, to empty the current port->inbuf,
> port->inbuf will be NULL even though there may be buffers left in the
> virtqueue.
> 
> This causes poll() to block even though there is data to be read,
> this patch fixes this by using will_read_block(port) instead of the
> port->inbuf != NULL check.
> 
> Signed-off-By: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Amit Shah <amit.shah@redhat.com>

Thanks.  I assume this one should go into stable too?

Cheers,
Rusty.

  parent reply	other threads:[~2010-09-20  2:49 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-16  9:13 [PATCH 1/2] virtio: console: Fix poll blocking even though there is data to read Amit Shah
2010-09-16  9:13 ` [PATCH 2/2] virtio: console: Disable lseek(2) for port file operations Amit Shah
2010-09-20  2:49 ` Rusty Russell [this message]
2010-09-20  5:08   ` [PATCH 1/2] virtio: console: Fix poll blocking even though there is data to read Amit Shah

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