This patch fixes two bugs that got introduced recently in setup_scsi_dh(): - Avoid that a memory leak occurs if attached_handler_name is not assigned to m->hw_handler_name. - Avoid that m->hw_handler_name becomes a dangling pointer if the RETAIN_ATTACHED_HW_HANDLER flag is set and scsi_dh_attach() returns -EBUSY.

Fixes: e8f74a0f0011 ("dm mpath: eliminate need to use scsi_device_from_queue") Signed-off-by: Bart Van Assche bvanassche@acm.org Cc: Martin K. Petersen martin.petersen@oracle.com Cc: stable@vger.kernel.org --- drivers/md/dm-mpath.c | 14 +++++++++----- include/scsi/scsi_device.h | 9 +++++++++ 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index d94ba6f72ff5..0ba58a537182 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -22,6 +22,7 @@ #include <linux/time.h> #include <linux/workqueue.h> #include <linux/delay.h> +#include <scsi/scsi_device.h> #include <scsi/scsi_dh.h> #include <linux/atomic.h> #include <linux/blk-mq.h> @@ -806,13 +807,15 @@ static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg, }

static int setup_scsi_dh(struct block_device *bdev, struct multipath *m, - const char *attached_handler_name, char **error) + char **error) { struct request_queue *q = bdev_get_queue(bdev); + const char *attached_handler_name; int r;

if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) { retain: + attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL); if (attached_handler_name) { /* * Clear any hw_handler_params associated with a @@ -867,7 +870,7 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps struct pgpath *p; struct multipath *m = ti->private; struct request_queue *q; - const char *attached_handler_name; + struct scsi_device *sdev;

/* we need at least a path arg */ if (as->argc < 1) { @@ -887,10 +890,11 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps }

q = bdev_get_queue(p->path.dev->bdev); - attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL); - if (attached_handler_name || m->hw_handler_name) { + sdev = scsi_device_from_queue(q); + if (sdev) { + put_device(&sdev->sdev_gendev); INIT_DELAYED_WORK(&p->activate_path, activate_path_work); - r = setup_scsi_dh(p->path.dev->bdev, m, attached_handler_name, &ti->error); + r = setup_scsi_dh(p->path.dev->bdev, m, &ti->error); if (r) { dm_put_device(ti, p->path.dev); goto bad; diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 202f4d6a4342..1c839089c711 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -2,6 +2,7 @@ #ifndef _SCSI_SCSI_DEVICE_H #define _SCSI_SCSI_DEVICE_H

+#include <linux/kconfig.h> #include <linux/list.h> #include <linux/spinlock.h> #include <linux/workqueue.h> @@ -335,7 +336,15 @@ extern void scsi_remove_device(struct scsi_device *); extern int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh); void scsi_attach_vpd(struct scsi_device *sdev);

+#if IS_ENABLED(CONFIG_SCSI) extern struct scsi_device *scsi_device_from_queue(struct request_queue *q); +#else +static inline struct scsi_device * +scsi_device_from_queue(struct request_queue *q) +{ + return NULL; +} +#endif extern int __must_check scsi_device_get(struct scsi_device *); extern void scsi_device_put(struct scsi_device *); extern struct scsi_device *scsi_device_lookup(struct Scsi_Host *,