[Xen-devel] [PATCH] xen-blkfront: move negotiate_mq to cover all cases of new VBDs

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

From: Bhavesh Davda <bhavesh.davda@xxxxxxxxxx>

negotiate_mq should happen in all cases of a new VBD being discovered by
xen-blkfront, whether called through _probe() or a hot-attached new VBD
from dom-0 via xenstore. Otherwise, hot-attached new VBDs are left
configured without multi-queue.

Signed-off-by: Bhavesh Davda <bhavesh.davda@xxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 drivers/block/xen-blkfront.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 891265acb10e..7d23225f79ed 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -262,6 +262,7 @@ static DEFINE_SPINLOCK(minor_lock);
 
 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 static void blkfront_gather_backend_features(struct blkfront_info *info);
+static int negotiate_mq(struct blkfront_info *info);
 
 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 {
@@ -1774,11 +1775,18 @@ static int talk_to_blkback(struct xenbus_device *dev,
        unsigned int i, max_page_order;
        unsigned int ring_page_order;
 
+       if (!info)
+               return -ENODEV;
+
        max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
                                              "max-ring-page-order", 0);
        ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
        info->nr_ring_pages = 1 << ring_page_order;
 
+       err = negotiate_mq(info);
+       if (err)
+               goto destroy_blkring;
+
        for (i = 0; i < info->nr_rings; i++) {
                struct blkfront_ring_info *rinfo = &info->rinfo[i];
 
@@ -1978,11 +1986,6 @@ static int blkfront_probe(struct xenbus_device *dev,
        }
 
        info->xbdev = dev;
-       err = negotiate_mq(info);
-       if (err) {
-               kfree(info);
-               return err;
-       }
 
        mutex_init(&info->mutex);
        info->vdevice = vdevice;
@@ -2099,10 +2102,6 @@ static int blkfront_resume(struct xenbus_device *dev)
 
        blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
 
-       err = negotiate_mq(info);
-       if (err)
-               return err;
-
        err = talk_to_blkback(dev, info);
        if (!err)
                blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
-- 
2.13.4


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