This is a note to let you know that I've just added the patch titled
net: ena: fix napi handler misbehavior when the napi budget is zero
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-ena-fix-napi-handler-misbehavior-when-the-napi-budget-is-zero.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu 02 Jan 2020 11:49:15 AM CET
From: Netanel Belgazal <netanel@xxxxxxxxxx>
Date: Tue, 10 Dec 2019 11:27:44 +0000
Subject: net: ena: fix napi handler misbehavior when the napi budget is zero
From: Netanel Belgazal <netanel@xxxxxxxxxx>
[ Upstream commit 24dee0c7478d1a1e00abdf5625b7f921467325dc ]
In netpoll the napi handler could be called with budget equal to zero.
Current ENA napi handler doesn't take that into consideration.
The napi handler handles Rx packets in a do-while loop.
Currently, the budget check happens only after decrementing the
budget, therefore the napi handler, in rare cases, could run over
MAX_INT packets.
In addition to that, this moves all budget related variables to int
calculation and stop mixing u32 to avoid ambiguity
Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Netanel Belgazal <netanel@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/amazon/ena/ena_netdev.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -1105,8 +1105,8 @@ static int ena_io_poll(struct napi_struc
struct ena_ring *tx_ring, *rx_ring;
struct ena_eth_io_intr_reg intr_reg;
- u32 tx_work_done;
- u32 rx_work_done;
+ int tx_work_done;
+ int rx_work_done = 0;
int tx_budget;
int napi_comp_call = 0;
int ret;
@@ -1122,7 +1122,11 @@ static int ena_io_poll(struct napi_struc
}
tx_work_done = ena_clean_tx_irq(tx_ring, tx_budget);
- rx_work_done = ena_clean_rx_irq(rx_ring, napi, budget);
+ /* On netpoll the budget is zero and the handler should only clean the
+ * tx completions.
+ */
+ if (likely(budget))
+ rx_work_done = ena_clean_rx_irq(rx_ring, napi, budget);
if ((budget > rx_work_done) && (tx_budget > tx_work_done)) {
napi_complete_done(napi, rx_work_done);
Patches currently in stable-queue which might be from netanel@xxxxxxxxxx are
queue-4.9/net-ena-fix-napi-handler-misbehavior-when-the-napi-budget-is-zero.patch
