Re: [PATCH] IB/mlx5: Fix outstanding_pi index for GSI qps

From: Leon Romanovsky <leon@kernel.org>
To: Prabhath Sajeepa <psajeepa@purestorage.com>
Cc: dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org, roland@purestorage.com
Subject: Re: [PATCH] IB/mlx5: Fix outstanding_pi index for GSI qps
Date: Wed, 18 Dec 2019 08:00:38 +0200	[thread overview]
Message-ID: <20191218060038.GL66555@unreal> (raw)
In-Reply-To: <1576195889-23527-1-git-send-email-psajeepa@purestorage.com>

On Thu, Dec 12, 2019 at 05:11:29PM -0700, Prabhath Sajeepa wrote:
> b0ffeb537f3a changed the way how outstanding WRs are tracked for GSI QP. But the
> fix did not cover the case when a call to ib_post_send fails and index
> to track outstanding WRs need to be updated correctly.
>
> Fixes: b0ffeb537f3a ('IB/mlx5: Fix iteration overrun in GSI qps ')
> Signed-off-by: Prabhath Sajeepa <psajeepa@purestorage.com>
> ---
>  drivers/infiniband/hw/mlx5/gsi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)

The description of this patch is better to be updated to include the
fact that outstanding_ci holds unwrapped version of outstanding_pi and
current code will generate wrong loop inside generate_completions(), due
to breaking assumption that outstanding_ci < outstanding_pi:

 79         for (index = gsi->outstanding_ci; index != gsi->outstanding_pi;
 80              index++) {

Thanks,
Acked-by: Leon Romanovsky <leonro@mellanox.com>