diff mbox series

[net-next,v2,1/2] ibmvnic: rework to ensure SCRQ entry reads are properly ordered

Message ID 20210130011905.1485-2-ljp@linux.ibm.com (mailing list archive)
State Accepted
Commit 665ab1eb18d7e8eaa8377fb8bf4924bfeb63bbce
Delegated to: Netdev Maintainers
Headers show
Series rework the memory barrier for SCRQ entry | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 6 maintainers not CCed: benh@kernel.crashing.org mpe@ellerman.id.au paulus@samba.org linuxppc-dev@lists.ozlabs.org davem@davemloft.net kuba@kernel.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 3 this patch: 3
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 55 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Lijun Pan Jan. 30, 2021, 1:19 a.m. UTC 
Move the dma_rmb() between pending_scrq() and ibmvnic_next_scrq()
into the end of pending_scrq() to save the duplicated code since
this dma_rmb will be used 3 times.

Signed-off-by: Lijun Pan <ljp@linux.ibm.com>
Acked-by: Thomas Falcon <tlfalcon@linux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 30 +++++++++++-------------------
 1 file changed, 11 insertions(+), 19 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index a40af510018a..331ebca2f57a 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2444,12 +2444,6 @@  static int ibmvnic_poll(struct napi_struct *napi, int budget)
 
 		if (!pending_scrq(adapter, rx_scrq))
 			break;
-		/* The queue entry at the current index is peeked at above
-		 * to determine that there is a valid descriptor awaiting
-		 * processing. We want to be sure that the current slot
-		 * holds a valid descriptor before reading its contents.
-		 */
-		dma_rmb();
 		next = ibmvnic_next_scrq(adapter, rx_scrq);
 		rx_buff =
 		    (struct ibmvnic_rx_buff *)be64_to_cpu(next->
@@ -3189,13 +3183,6 @@  static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter,
 		int total_bytes = 0;
 		int num_packets = 0;
 
-		/* The queue entry at the current index is peeked at above
-		 * to determine that there is a valid descriptor awaiting
-		 * processing. We want to be sure that the current slot
-		 * holds a valid descriptor before reading its contents.
-		 */
-		dma_rmb();
-
 		next = ibmvnic_next_scrq(adapter, scrq);
 		for (i = 0; i < next->tx_comp.num_comps; i++) {
 			if (next->tx_comp.rcs[i])
@@ -3569,11 +3556,16 @@  static int pending_scrq(struct ibmvnic_adapter *adapter,
 			struct ibmvnic_sub_crq_queue *scrq)
 {
 	union sub_crq *entry = &scrq->msgs[scrq->cur];
+	int rc;
 
-	if (entry->generic.first & IBMVNIC_CRQ_CMD_RSP)
-		return 1;
-	else
-		return 0;
+	rc = !!(entry->generic.first & IBMVNIC_CRQ_CMD_RSP);
+
+	/* Ensure that the SCRQ valid flag is loaded prior to loading the
+	 * contents of the SCRQ descriptor
+	 */
+	dma_rmb();
+
+	return rc;
 }
 
 static union sub_crq *ibmvnic_next_scrq(struct ibmvnic_adapter *adapter,
@@ -3592,8 +3584,8 @@  static union sub_crq *ibmvnic_next_scrq(struct ibmvnic_adapter *adapter,
 	}
 	spin_unlock_irqrestore(&scrq->lock, flags);
 
-	/* Ensure that the entire buffer descriptor has been
-	 * loaded before reading its contents
+	/* Ensure that the SCRQ valid flag is loaded prior to loading the
+	 * contents of the SCRQ descriptor
 	 */
 	dma_rmb();