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From:   Sergei Trofimovich <slyfox@gentoo.org>
To:     "Martin K. Petersen" <martin.petersen@oracle.com>,
        Arnd Bergmann <arnd@kernel.org>,
        John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        Don Brace <don.brace@microchip.com>,
        linux-ia64@vger.kernel.org, storagedev@microchip.com,
        linux-scsi <linux-scsi@vger.kernel.org>, jszczype@redhat.com,
        Scott Benesh <scott.benesh@microchip.com>,
        Scott Teel <scott.teel@microchip.com>, thenzl@redhat.com
Cc:     linux-kernel@vger.kernel.org,
        Sergei Trofimovich <slyfox@gentoo.org>
Subject: [PATCH v2 2/3] hpsa: fix boot on ia64 (atomic_t alignment)
Date:   Tue, 30 Mar 2021 08:19:57 +0100
Message-Id: <20210330071958.3788214-2-slyfox@gentoo.org>
In-Reply-To: <20210330071958.3788214-1-slyfox@gentoo.org>
References: <yq1wntpgxxr.fsf@ca-mkp.ca.oracle.com>
 <20210330071958.3788214-1-slyfox@gentoo.org>
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The failure initially observed as boot failure on rx3600 ia64 machine
with RAID bus controller: Hewlett-Packard Company Smart Array P600:

    kernel unaligned access to 0xe000000105dd8b95, ip=0xa000000100b87551
    kernel unaligned access to 0xe000000105dd8e95, ip=0xa000000100b87551
    hpsa 0000:14:01.0: Controller reports max supported commands of 0 Using 16 instead. Ensure that firmware is up to date.
    swapper/0[1]: error during unaligned kernel access

Here unaligned access comes from 'struct CommandList' that happens
to be packed. The change f749d8b7a ("scsi: hpsa: Correct dev cmds
outstanding for retried cmds") introduced unexpected padding and
un-aligned atomic_t from natural alignment to something else.

This change removes packing annotation from struct not intended to be
sent to controller as is. This restores natural `atomic_t` alignment.

The change is tested on the same rx3600 machine.

CC: linux-ia64@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: storagedev@microchip.com
CC: linux-scsi@vger.kernel.org
CC: Joe Szczypek <jszczype@redhat.com>
CC: Scott Benesh <scott.benesh@microchip.com>
CC: Scott Teel <scott.teel@microchip.com>
CC: Tomas Henzl <thenzl@redhat.com>
CC: "Martin K. Petersen" <martin.petersen@oracle.com>
CC: Don Brace <don.brace@microchip.com>
Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Suggested-by: Don Brace <don.brace@microchip.com>
Fixes: f749d8b7a "scsi: hpsa: Correct dev cmds outstanding for retried cmds"
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
---
 drivers/scsi/hpsa_cmd.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/hpsa_cmd.h b/drivers/scsi/hpsa_cmd.h
index 280e933d27e7..885b1f1fb20a 100644
--- a/drivers/scsi/hpsa_cmd.h
+++ b/drivers/scsi/hpsa_cmd.h
@@ -452,7 +452,7 @@ struct CommandList {
 	bool retry_pending;
 	struct hpsa_scsi_dev_t *device;
 	atomic_t refcount; /* Must be last to avoid memset in hpsa_cmd_init() */
-} __packed __aligned(COMMANDLIST_ALIGNMENT);
+} __aligned(COMMANDLIST_ALIGNMENT);
 
 /* Max S/G elements in I/O accelerator command */
 #define IOACCEL1_MAXSGENTRIES           24
-- 
2.31.1