[PATCH 5.15 049/148] net: mana: Add rmb after checking owner bits

Greg Kroah-Hartman
2022-09-26T11:15:24Z

From: Haiyang Zhang <haiyangz@microsoft.com>

commit 6fd2c68da55c552f86e401ebe40c4a619025ef69 upstream.

Per GDMA spec, rmb is necessary after checking owner_bits, before
reading EQ or CQ entries.

Add rmb in these two places to comply with the specs.

Cc: stable@vger.kernel.org
Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
Reported-by: Sinan Kaya <Sinan.Kaya@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Link: https://lore.kernel.org/r/1662928805-15861-1-git-send-email-haiyangz@microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/microsoft/mana/gdma_main.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -368,6 +368,11 @@ static void mana_gd_process_eq_events(vo
break;
}

+ /* Per GDMA spec, rmb is necessary after checking owner_bits, before
+ * reading eqe.
+ */
+ rmb();
+
mana_gd_process_eqe(eq);

eq->head++;
@@ -1096,6 +1101,11 @@ static int mana_gd_read_cqe(struct gdma_
if (WARN_ON_ONCE(owner_bits != new_bits))
return -1;

+ /* Per GDMA spec, rmb is necessary after checking owner_bits, before
+ * reading completion info
+ */
+ rmb();
+
comp->wq_num = cqe->cqe_info.wq_num;
comp->is_sq = cqe->cqe_info.is_sq;
memcpy(comp->cqe_data, cqe->cqe_data, GDMA_COMP_DATA_SIZE);