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Commit 4d6acb62 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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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: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Ariel Elior <ariel.elior@qlogic.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 46c749ea

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c

+21 −30
Original line number Diff line number Diff line
@@ -3204,13 +3204,12 @@ 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);
@@ -3221,25 +3220,16 @@ static int bnx2x_poll(struct napi_struct *napi, int budget) 
		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);



			/* 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))) {

	rx_work_done = (bnx2x_has_rx_work(fp)) ? bnx2x_rx_int(fp, budget) : 0;



	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);

				break;

			}

		} 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