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

[Haiyang Zhang]

> -----Original Message-----
> From: Haiyang Zhang [mailto:haiyangz@xxxxxxxxxxxxx]
> Sent: Friday, December 02, 2011 2:56 PM
> To: Haiyang Zhang; KY Srinivasan; davem@xxxxxxxxxxxxx; gregkh@xxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx
> 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@xxxxxxxxxxxxx>
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> Reported-by: Long Li <longli@xxxxxxxxxxxxx>
> ---
>  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?

Thanks,
-  Haiyang


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