[Qemu-devel] [PATCH] block/nvme: call blk_drain in NVMe reset code to avoid lockups

[Igor Druzhinin <igor.druzhinin@citrix.com>]

When blk_flush called in NVMe reset path S/C queues are already freed
which means that re-entering AIO handling loop having some IO requests
unfinished will lockup or crash as their SG structures being potentially
reused. Call blk_drain before freeing the queues to avoid this nasty
scenario.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
---
 hw/block/nvme.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index fc7dacb..cdf836e 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -797,6 +797,8 @@ static void nvme_clear_ctrl(NvmeCtrl *n)
 {
     int i;
 
+    blk_drain(n->conf.blk);
+
     for (i = 0; i < n->num_queues; i++) {
         if (n->sq[i] != NULL) {
             nvme_free_sq(n->sq[i], n);
-- 
2.7.4