linux-kernel - [PATCH 4.19 65/79] net: aquantia: fix out of memory condition on rx side

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Message-Id: <20190919214813.375849733@linuxfoundation.org>
Date:   Fri, 20 Sep 2019 00:03:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Igor Russkikh <igor.russkikh@...antia.com>,
        Dmitry Bogdanov <dmitry.bogdanov@...antia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 65/79] net: aquantia: fix out of memory condition on rx side

From: Dmitry Bogdanov <dmitry.bogdanov@...antia.com>

[ Upstream commit be6cef69ba570ebb327eba1ef6438f7af49aaf86 ]

On embedded environments with hard memory limits it is a normal although
rare case when skb can't be allocated on rx part under high traffic.

In such OOM cases napi_complete_done() was not called.
So the napi object became in an invalid state like it is "scheduled".
Kernel do not re-schedules the poll of that napi object.

Consequently, kernel can not remove that object the system hangs on
`ifconfig down` waiting for a poll.

We are fixing this by gracefully closing napi poll routine with correct
invocation of napi_complete_done.

This was reproduced with artificially failing the allocation of skb to
simulate an "out of memory" error case and check that traffic does
not get stuck.

Fixes: 970a2e9864b0 ("net: ethernet: aquantia: Vector operations")
Signed-off-by: Igor Russkikh <igor.russkikh@...antia.com>
Signed-off-by: Dmitry Bogdanov <dmitry.bogdanov@...antia.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/ethernet/aquantia/atlantic/aq_vec.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_vec.c b/drivers/net/ethernet/aquantia/atlantic/aq_vec.c
index d335c334fa561..82582fa54d5d2 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_vec.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_vec.c
@@ -89,6 +89,7 @@ static int aq_vec_poll(struct napi_struct *napi, int budget)
 			}
 		}
 
+err_exit:
 		if (!was_tx_cleaned)
 			work_done = budget;
 
@@ -98,7 +99,7 @@ static int aq_vec_poll(struct napi_struct *napi, int budget)
 					1U << self->aq_ring_param.vec_idx);
 		}
 	}
-err_exit:
+
 	return work_done;
 }
 
-- 
2.20.1