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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Sinan Kaya <Sinan.Kaya@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Dexuan Cui <decui@microsoft.com>,
        Jakub Kicinski <kuba@kernel.org>
Subject: [PATCH 5.15 049/148] net: mana: Add rmb after checking owner bits
Date:   Mon, 26 Sep 2022 12:11:23 +0200
Message-Id: <20220926100757.863881132@linuxfoundation.org>
In-Reply-To: <20220926100756.074519146@linuxfoundation.org>
References: <20220926100756.074519146@linuxfoundation.org>
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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);