cnic: Prevent status block race conditions with hardware
The status block index is used to acknowledge interrupt events and must
be read before checking for the interrupt events, so we need to add rmb()
to guarantee that.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/cnic.c b/drivers/net/cnic.c
index 7ff170c..b0d9e4a 100644
--- a/drivers/net/cnic.c
+++ b/drivers/net/cnic.c
@@ -2760,6 +2760,8 @@
u32 status_idx = (u16) *cp->kcq1.status_idx_ptr;
int kcqe_cnt;
+ /* status block index must be read before reading other fields */
+ rmb();
cp->kwq_con_idx = *cp->kwq_con_idx_ptr;
while ((kcqe_cnt = cnic_get_kcqes(dev, &cp->kcq1))) {
@@ -2770,6 +2772,8 @@
barrier();
if (status_idx != *cp->kcq1.status_idx_ptr) {
status_idx = (u16) *cp->kcq1.status_idx_ptr;
+ /* status block index must be read first */
+ rmb();
cp->kwq_con_idx = *cp->kwq_con_idx_ptr;
} else
break;
@@ -2888,6 +2892,8 @@
u32 last_status = *info->status_idx_ptr;
int kcqe_cnt;
+ /* status block index must be read before reading the KCQ */
+ rmb();
while ((kcqe_cnt = cnic_get_kcqes(dev, info))) {
service_kcqes(dev, kcqe_cnt);
@@ -2898,6 +2904,8 @@
break;
last_status = *info->status_idx_ptr;
+ /* status block index must be read before reading the KCQ */
+ rmb();
}
return last_status;
}