[PATCH AUTOSEL 4.19 51/52] net: aquantia: fix out of memory condition on rx side

From: Sasha Levin
Date: Wed Sep 04 2019 - 12:09:11 EST

From: Dmitry Bogdanov <dmitry.bogdanov@xxxxxxxxxxxx>

[ 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@xxxxxxxxxxxx>
Signed-off-by: Dmitry Bogdanov <dmitry.bogdanov@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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)

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);
return work_done;