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From: Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Roland Dreier <roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Yishai Hadas <yishaih-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] IB/mlx4: Allocation of CQ resize structure doesn't need to be atomic
Date: Sun, 31 Jul 2016 09:42:45 +0300	[thread overview]
Message-ID: <20160731064245.GX4628@leon.nu> (raw)
In-Reply-To: <1469768323-8093-1-git-send-email-roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

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On Thu, Jul 28, 2016 at 09:58:43PM -0700, Roland Dreier wrote:
> From: Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
> 
> We allocate a small tracking structure as part of mlx4_ib_resize_cq().
> However, we don't need to use GFP_ATOMIC -- immediately after the
> allocation, we call mlx4_cq_resize(), which allocates a command
> mailbox with GFP_KERNEL and then sleeps on a firmware command, so we
> better not be in an atomic context.
> 
> This actually has a real impact, because when this GFP_ATOMIC
> allocation fails (and GFP_ATOMIC does fail in practice) then a
> userspace consumer resizing a CQ will get a spurious failure that we
> can easily avoid.
> 
> Signed-off-by: Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>

Thanks,
Reviewed-by: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

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  parent reply	other threads:[~2016-07-31  6:42 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-29  4:58 [PATCH] IB/mlx4: Allocation of CQ resize structure doesn't need to be atomic Roland Dreier
     [not found] ` <1469768323-8093-1-git-send-email-roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-07-31  6:42   ` Leon Romanovsky [this message]
2016-08-02 17:52   ` Doug Ledford

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