vhost/scsi: Use GFP_ATOMIC with percpu_ida_alloc for obtaining tag

Fix GFP_KERNEL -> GFP_ATOMIC usage of percpu_ida_alloc() within
vhost_scsi_get_tag(), as this code is expected to be called directly
from interrupt context.

v2 changes:

  - Handle possible tag < 0 failure with GFP_ATOMIC

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Asias He <asias@redhat.com>
Cc: Kent Overstreet <kmo@daterainc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 592b31698fc8..ce5221fa393a 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -728,7 +728,12 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq,
         }
         se_sess = tv_nexus->tvn_se_sess;
 
-        tag = percpu_ida_alloc(&se_sess->sess_tag_pool, GFP_KERNEL);
+        tag = percpu_ida_alloc(&se_sess->sess_tag_pool, GFP_ATOMIC);
+        if (tag < 0) {
+                pr_err("Unable to obtain tag for tcm_vhost_cmd\n");
+                return ERR_PTR(-ENOMEM);
+        }
+
         cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[tag];
         sg = cmd->tvc_sgl;
         pages = cmd->tvc_upages;