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bnx2x: avoid soft lockup in bnx2x_poll() 

Under heavy TX load, bnx2x_poll() can loop forever and trigger
soft lockup bugs.

A napi poll handler must yield after one TX completion round,
risk of livelock is too high otherwise.

Bug is very easy to trigger using a debug build, and udp flood, because
of added cpu cycles in TX completion, and we do not receive enough
packets to break the loop.

Reported-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ariel Elior <ariel.elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-12-08 05:54:40 -08:00 committed by David S. Miller
parent 46c749eac9
commit 4d6acb62d2
1 changed files with 21 additions and 30 deletions
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51
drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
View File

@ -3204,42 +3204,32 @@ int bnx2x_set_power_state(struct bnx2x *bp, pci_power_t state)
*/
static int bnx2x_poll(struct napi_struct *napi, int budget)
{
int work_done = 0;
u8 cos;
struct bnx2x_fastpath *fp = container_of(napi, struct bnx2x_fastpath,
napi);
struct bnx2x *bp = fp->bp;
int rx_work_done;
u8 cos;
while (1) {
#ifdef BNX2X_STOP_ON_ERROR
if (unlikely(bp->panic)) {
napi_complete(napi);
return 0;
}
if (unlikely(bp->panic)) {
napi_complete(napi);
return 0;
}
#endif
for_each_cos_in_tx_queue(fp, cos)
if (bnx2x_tx_queue_has_work(fp->txdata_ptr[cos]))
bnx2x_tx_int(bp, fp->txdata_ptr[cos]);
for_each_cos_in_tx_queue(fp, cos)
if (bnx2x_tx_queue_has_work(fp->txdata_ptr[cos]))
bnx2x_tx_int(bp, fp->txdata_ptr[cos]);
if (bnx2x_has_rx_work(fp)) {
work_done += bnx2x_rx_int(fp, budget - work_done);
rx_work_done = (bnx2x_has_rx_work(fp)) ? bnx2x_rx_int(fp, budget) : 0;
/* must not complete if we consumed full budget */
if (work_done >= budget)
break;
}
/* Fall out from the NAPI loop if needed */
if (!(bnx2x_has_rx_work(fp) || bnx2x_has_tx_work(fp))) {
/* No need to update SB for FCoE L2 ring as long as
* it's connected to the default SB and the SB
* has been updated when NAPI was scheduled.
*/
if (IS_FCOE_FP(fp)) {
napi_complete(napi);
break;
}
if (rx_work_done < budget) {
/* No need to update SB for FCoE L2 ring as long as
* it's connected to the default SB and the SB
* has been updated when NAPI was scheduled.
*/
if (IS_FCOE_FP(fp)) {
napi_complete(napi);
} else {
bnx2x_update_fpsb_idx(fp);
/* bnx2x_has_rx_work() reads the status block,
* thus we need to ensure that status block indices
@ -3264,12 +3254,13 @@ static int bnx2x_poll(struct napi_struct *napi, int budget)
bnx2x_ack_sb(bp, fp->igu_sb_id, USTORM_ID,
le16_to_cpu(fp->fp_hc_idx),
IGU_INT_ENABLE, 1);
break;
} else {
rx_work_done = budget;
}
}
}
return work_done;
return rx_work_done;
}
/* we split the first BD into headers and data BDs