[PATCH] sg: reset 'res_in_use' after unlinking reserved array

[Hannes Reinecke <hare@suse.de>]

Once the reserved page array is unused we can reset the
'res_in_use' state; here we can do a lazy update without
holding the mutex as we only need to check against
concurrent access, not concurrent release.

Fixes: 1bc0eb0 ("scsi: sg: protect accesses to 'reserved' page array")
Signed-off-by: Hannes Reinecke <hare@suse.com>
---
 drivers/scsi/sg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 8147147..06503c1 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -2056,6 +2056,8 @@ static long sg_compat_ioctl(struct file *filp, unsigned int cmd_in, unsigned lon
 	req_schp->page_order = 0;
 	req_schp->sglist_len = 0;
 	srp->res_used = 0;
+	/* Called without mutex lock to avoid deadlock */
+	sfp->res_in_use = 0;
 }
 
 static Sg_request *
-- 
1.8.5.6