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net: ena: fix napi handler misbehavior when the napi budget is zero

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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: 1738cd3ed3 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Netanel Belgazal <netanel@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Netanel Belgazal 2019-12-10 11:27:44 +00:00 committed by David S. Miller
parent f1ce0a1557
commit 24dee0c747
1 changed files with 7 additions and 3 deletions
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10
drivers/net/ethernet/amazon/ena/ena_netdev.c
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@ -1238,8 +1238,8 @@ static int ena_io_poll(struct napi_struct *napi, int budget)
struct ena_napi *ena_napi = container_of(napi, struct ena_napi, napi);
struct ena_ring *tx_ring, *rx_ring;
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;
@ -1256,7 +1256,11 @@ static int ena_io_poll(struct napi_struct *napi, int budget)
}
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 the device is about to reset or down, avoid unmask
* the interrupt and return 0 so NAPI won't reschedule