[PATCH] net/hyperv: Fix the stop/wake queue mechanism

Haiyang Zhang haiyangz at microsoft.com
Fri Dec 9 16:00:59 UTC 2011

> -----Original Message-----
> From: Haiyang Zhang [mailto:haiyangz at microsoft.com]
> Sent: Friday, December 02, 2011 2:56 PM
> To: Haiyang Zhang; KY Srinivasan; davem at davemloft.net; gregkh at suse.de;
> linux-kernel at vger.kernel.org; netdev at vger.kernel.org;
> devel at linuxdriverproject.org
> Subject: [PATCH] net/hyperv: Fix the stop/wake queue mechanism
> The ring buffer is only used to pass meta data for outbound packets. The
> actual payload is accessed by DMA from the host. So the stop/wake queue
> mechanism based on counting and comparing number of pages sent v.s.
> number
> of pages in the ring buffer is wrong. Also, there is a race condition in
> the stop/wake queue calls, which can stop xmit queue forever.
> The new stop/wake queue mechanism is based on the actual bytes used by
> outbound packets in the ring buffer. The check for number of outstanding
> sends after stop queue prevents the race condition that can cause wake
> queue happening earlier than stop queue.
> Signed-off-by: Haiyang Zhang <haiyangz at microsoft.com>
> Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
> Reported-by: Long Li <longli at microsoft.com>
> ---
>  drivers/net/hyperv/netvsc.c     |   14 +++++++++++---
>  drivers/net/hyperv/netvsc_drv.c |   24 +-----------------------
>  2 files changed, 12 insertions(+), 26 deletions(-)

Hi Greg,

Since the netvsc haven't been merged into Dave's tree yet after out of staging,
could you consider this patch for your tree?

-  Haiyang

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