bnx2x: napi_poll budget check
Check the napi_poll budget only when updating it. Also add a comment to explain
the rmb
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c
index a66536e..e0851a7 100644
--- a/drivers/net/bnx2x_main.c
+++ b/drivers/net/bnx2x_main.c
@@ -10068,14 +10068,27 @@
if (bnx2x_has_tx_work(fp))
bnx2x_tx_int(fp);
- if (bnx2x_has_rx_work(fp))
+ if (bnx2x_has_rx_work(fp)) {
work_done = bnx2x_rx_int(fp, budget);
- rmb(); /* BNX2X_HAS_WORK() reads the status block */
+ /* must not complete if we consumed full budget */
+ if (work_done >= budget)
+ goto poll_again;
+ }
- /* must not complete if we consumed full budget */
- if ((work_done < budget) && !BNX2X_HAS_WORK(fp)) {
+ /* BNX2X_HAS_WORK() reads the status block, thus we need to
+ * ensure that status block indices have been actually read
+ * (bnx2x_update_fpsb_idx) prior to this check (BNX2X_HAS_WORK)
+ * so that we won't write the "newer" value of the status block to IGU
+ * (if there was a DMA right after BNX2X_HAS_WORK and
+ * if there is no rmb, the memory reading (bnx2x_update_fpsb_idx)
+ * may be postponed to right before bnx2x_ack_sb). In this case
+ * there will never be another interrupt until there is another update
+ * of the status block, while there is still unhandled work.
+ */
+ rmb();
+ if (!BNX2X_HAS_WORK(fp)) {
#ifdef BNX2X_STOP_ON_ERROR
poll_panic:
#endif
@@ -10087,6 +10100,7 @@
le16_to_cpu(fp->fp_c_idx), IGU_INT_ENABLE, 1);
}
+poll_again:
return work_done;
}