iwlwifi: read the Rx write pointer only once
The FH (DMA engine) tells the driver the index of the last
ready (closed) Rx buffer. This data is in closed_rb_num.
If we read this data several times we may get inconsistencies
between the code and the debug prints which can make it
harder to debug issues here.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/pcie/rx.c b/drivers/net/wireless/iwlwifi/pcie/rx.c
index c81b978..787b9ca 100644
--- a/drivers/net/wireless/iwlwifi/pcie/rx.c
+++ b/drivers/net/wireless/iwlwifi/pcie/rx.c
@@ -698,7 +698,7 @@
/* uCode's read index (stored in shared DRAM) indicates the last Rx
* buffer that the driver may process (last buffer filled by ucode). */
- r = le16_to_cpu(rxq->rb_stts->closed_rb_num) & 0x0FFF;
+ r = le16_to_cpu(ACCESS_ONCE(rxq->rb_stts->closed_rb_num)) & 0x0FFF;
i = rxq->read;
/* Rx interrupt, but nothing sent from uCode */