Commit 67a95e20 authored by Michael Chan's avatar Michael Chan Committed by David S. Miller
Browse files

bnxt_en: Need memory barrier when processing the completion ring.



The code determines if the next ring entry is valid before proceeding
further to read the rest of the entry.  The CPU can re-order and read
the rest of the entry first, possibly reading a stale entry, if DMA
of a new entry happens right after reading it.  This issue can be
readily seen on a ppc64 system, causing it to crash.
Signed-off-by: default avatarMichael Chan <michael.chan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 32b583a0
......@@ -1388,6 +1388,10 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
if (!TX_CMP_VALID(txcmp, raw_cons))
break;
/* The valid test of the entry must be done first before
* reading any further.
*/
rmb();
if (TX_CMP_TYPE(txcmp) == CMP_TYPE_TX_L2_CMP) {
tx_pkts++;
/* return full budget so NAPI will complete. */
......
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