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authorMichael Chan <michael.chan@broadcom.com>2016-05-04 16:56:43 -0400
committerDavid S. Miller <davem@davemloft.net>2016-05-04 17:11:37 -0400
commit67a95e2022c7f0405408fb1f910283785ece354a (patch)
treeba7439fac778de34a693ee7a3b0d446f70c5a8ba /drivers/net
parent32b583a0cb9b757d68c44f2819fa6ccf95dbb953 (diff)
downloadleg-kernel-67a95e2022c7f0405408fb1f910283785ece354a.tar.gz
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: Michael Chan <michael.chan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/broadcom/bnxt/bnxt.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 72eb29ed0359..f33ff205a0ea 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -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. */