From: Eric Dumazet <eric.dumazet@gmail.com>
To: Song Liu <songliubraving@fb.com>, netdev@vger.kernel.org
Cc: intel-wired-lan@lists.osuosl.org, kernel-team@fb.com,
stable@vger.kernel.org,
Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Subject: Re: [PATCH net] ixgbe: check return value of napi_complete_done()
Date: Thu, 20 Sep 2018 13:35:00 -0700 [thread overview]
Message-ID: <c1251d5d-4b18-a1de-acd2-6de829b7c7ac@gmail.com> (raw)
In-Reply-To: <20180920190113.490005-1-songliubraving@fb.com>
On 09/20/2018 12:01 PM, Song Liu wrote:
> The NIC driver should only enable interrupts when napi_complete_done()
> returns true. This patch adds the check for ixgbe.
>
> Cc: stable@vger.kernel.org # 4.10+
> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> Suggested-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Song Liu <songliubraving@fb.com>
> ---
Well, unfortunately we do not know why this is needed,
this is why I have not yet sent this patch formally.
netpoll has correct synchronization :
poll_napi() places into napi->poll_owner current cpu number before calling poll_one_napi()
netpoll_poll_lock() does also use napi->poll_owner
When netpoll calls ixgbe poll() method, it passed a budget of 0,
meaning napi_complete_done() is not called.
As long as we can not explain the problem properly in the changelog,
we should investigate, otherwise we will probably see coming dozens of patches
trying to fix a 'potential hazard'.
Thanks.
next prev parent reply other threads:[~2018-09-20 20:35 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 19:01 [PATCH net] ixgbe: check return value of napi_complete_done() Song Liu
2018-09-20 20:35 ` Eric Dumazet [this message]
2018-09-20 21:01 ` Jeff Kirsher
2018-09-20 22:42 ` Song Liu
2018-09-20 23:22 ` Eric Dumazet
2018-09-20 23:43 ` Song Liu
2018-09-20 23:49 ` Eric Dumazet
2018-09-21 7:17 ` Song Liu
2018-09-21 13:33 ` Eric Dumazet
2018-09-21 14:55 ` Alexei Starovoitov
2018-09-21 14:59 ` Eric Dumazet
2018-09-21 15:14 ` Alexei Starovoitov
2018-09-21 15:43 ` Eric Dumazet
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