[PATCH 3/7] remoteproc: safer boot/shutdown order

[Ohad Ben-Cohen]

Boot the remote processor only after setting up the virtqueues,
and shut it down before deleting them.

Remote processors should obey virtio status changes, and
therefore not manipulate/trigger the virtqueues while the virtio
driver isn't ready, but it's just safer not to rely on that
(plus a vq access might already be inflight while a vdev
status is changed).

We also don't have yet status change notifications, but that's
a temporary limitation.

Signed-off-by: Ohad Ben-Cohen <ohad at wizery.com>
Cc: Brian Swetland <swetland at google.com>
Cc: Iliyan Malchev <malchev at google.com>
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: Grant Likely <grant.likely at secretlab.ca>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: Mark Grosen <mgrosen at ti.com>
Cc: John Williams <john.williams at petalogix.com>
Cc: Michal Simek <monstr at monstr.eu>
Cc: Loic PALLARDY <loic.pallardy at stericsson.com>
Cc: Ludovic BARRE <ludovic.barre at stericsson.com>
Cc: Omar Ramirez Luna <omar.luna at linaro.org>
Cc: Guzman Lugo Fernando <fernando.lugo at ti.com>
Cc: Anna Suman <s-anna at ti.com>
Cc: Clark Rob <rob at ti.com>
Cc: Stephen Boyd <sboyd at codeaurora.org>
Cc: Saravana Kannan <skannan at codeaurora.org>
Cc: David Brown <davidb at codeaurora.org>
Cc: Kieran Bingham <kieranbingham at gmail.com>
Cc: Tony Lindgren <tony at atomide.com>
---
 drivers/remoteproc/remoteproc_virtio.c |   20 ++++++++++----------
 1 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
index 4f73e81..78d8527 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -123,14 +123,14 @@ static void rproc_virtio_del_vqs(struct virtio_device *vdev)
 	struct virtqueue *vq, *n;
 	struct rproc *rproc = vdev_to_rproc(vdev);
 
+	/* power down the remote processor before deleting vqs */
+	rproc_shutdown(rproc);
+
 	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
 		struct rproc_virtio_vq_info *rpvq = vq->priv;
 		vring_del_virtqueue(vq);
 		kfree(rpvq);
 	}
-
-	/* power down the remote processor */
-	rproc_shutdown(rproc);
 }
 
 static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
@@ -145,13 +145,6 @@ static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 	if (nvqs != 2)
 		return -EINVAL;
 
-	/* boot the remote processor */
-	ret = rproc_boot(rproc);
-	if (ret) {
-		dev_err(rproc->dev, "rproc_boot() failed %d\n", ret);
-		goto error;
-	}
-
 	for (i = 0; i < nvqs; ++i) {
 		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
 		if (IS_ERR(vqs[i])) {
@@ -160,6 +153,13 @@ static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 		}
 	}
 
+	/* now that the vqs are all set, boot the remote processor */
+	ret = rproc_boot(rproc);
+	if (ret) {
+		dev_err(rproc->dev, "rproc_boot() failed %d\n", ret);
+		goto error;
+	}
+
 	return 0;
 
 error:
-- 
1.7.5.4