From: Bart Van Assche <bart.vanassche@wdc.com>
Date: Thu, 17 Aug 2017 20:12:46 +0000 (-0700)
Subject: skd: Submit requests to firmware before triggering the doorbell
X-Git-Tag: v4.14-rc1~81^2~124
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=5fbd545cd3fd311ea1d6e8be4cedddd0ee5684c7;p=linux.git

skd: Submit requests to firmware before triggering the doorbell

Ensure that the members of struct skd_msg_buf have been transferred
to the PCIe adapter before the doorbell is triggered. This patch
avoids that I/O fails sporadically and that the following error
message is reported:

(skd0:STM000196603:[0000:00:09.0]): Completion mismatch comp_id=0x0000 skreq=0x0400 new=0x0000

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/drivers/block/skd_main.c b/drivers/block/skd_main.c
index edab9c04e8ad..153f20ce318b 100644
--- a/drivers/block/skd_main.c
+++ b/drivers/block/skd_main.c
@@ -2160,6 +2160,9 @@ static void skd_send_fitmsg(struct skd_device *skdev,
 		 */
 		qcmd |= FIT_QCMD_MSGSIZE_64;
 
+	/* Make sure skd_msg_buf is written before the doorbell is triggered. */
+	smp_wmb();
+
 	SKD_WRITEQ(skdev, qcmd, FIT_Q_COMMAND);
 }
 
@@ -2202,6 +2205,9 @@ static void skd_send_special_fitmsg(struct skd_device *skdev,
 	qcmd = skspcl->mb_dma_address;
 	qcmd |= FIT_QCMD_QID_NORMAL + FIT_QCMD_MSGSIZE_128;
 
+	/* Make sure skd_msg_buf is written before the doorbell is triggered. */
+	smp_wmb();
+
 	SKD_WRITEQ(skdev, qcmd, FIT_Q_COMMAND);
 }