2.6.29-stable review patch. If anyone has any objections, please let us know. ------------------ From: Michael Chan commit 581daf7e00c5e766f26aff80a61a860a17b0d75a upstream. Add barrier() to bnx2_get_hw_{tx|rx}_cons() to fix this issue: http://bugzilla.kernel.org/show_bug.cgi?id=12698 This issue was reported by multiple i386 users. Without barrier(), the compiled code looks like the following where %eax contains the address of the tx_cons or rx_cons in the DMA status block. The status block contents can change between the cmpb and the movzwl instruction. The driver would crash if the value was not 0xff during the cmpb instruction, but changed to 0xff during the movzwl instruction. 6828: 80 38 ff cmpb $0xff,(%eax) 682b: 0f b7 10 movzwl (%eax),%edx With the added barrier(), the compiled code now looks correct: 683d: 0f b7 10 movzwl (%eax),%edx 6840: 0f b6 c2 movzbl %dl,%eax 6843: 3d ff 00 00 00 cmp $0xff,%eax Thanks to Pascal de Bruijn for reporting the problem and Holger Noefer for patiently testing test patches for us. [greg - took out version change] Signed-off-by: Michael Chan Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/bnx2.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/net/bnx2.c +++ b/drivers/net/bnx2.c @@ -2585,6 +2585,7 @@ bnx2_get_hw_tx_cons(struct bnx2_napi *bn /* Tell compiler that status block fields can change. */ barrier(); cons = *bnapi->hw_tx_cons_ptr; + barrier(); if (unlikely((cons & MAX_TX_DESC_CNT) == MAX_TX_DESC_CNT)) cons++; return cons; @@ -2864,6 +2865,7 @@ bnx2_get_hw_rx_cons(struct bnx2_napi *bn /* Tell compiler that status block fields can change. */ barrier(); cons = *bnapi->hw_rx_cons_ptr; + barrier(); if (unlikely((cons & MAX_RX_DESC_CNT) == MAX_RX_DESC_CNT)) cons++; return cons; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/