SCSI fixes on 20161001

One final fix before 4.8: there's a memory leak triggered by turning scsi mq
 off due to the fact that we assume on host release that the already running
 hosts weren't mq based because that's the state of the global flag (even
 though they were), so fix it by tracking this on a per host host basis.
 
 Signed-off-by: James Bottomley <jejb@linux.vnet.ibm.com>
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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI fix from James Bottomley:
 "One final fix before 4.8.

  There was a memory leak triggered by turning scsi mq off due to the
  fact that we assume on host release that the already running hosts
  weren't mq based because that's the state of the global flag (even
  though they were).

  Fix it by tracking this on a per host host basis"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: Avoid that toggling use_blk_mq triggers a memory leak

drivers/scsi/hosts.c

@@ -486,6 +486,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 	else
 		shost->dma_boundary = 0xffffffff;
 
+	shost->use_blk_mq = scsi_use_blk_mq;
+
 	device_initialize(&shost->shost_gendev);
 	dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
 	shost->shost_gendev.bus = &scsi_bus_type;

drivers/scsi/scsi.c

@@ -1160,7 +1160,6 @@ bool scsi_use_blk_mq = true;
 bool scsi_use_blk_mq = false;
 #endif
 module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO);
-EXPORT_SYMBOL_GPL(scsi_use_blk_mq);
 
 static int __init init_scsi(void)
 {

drivers/scsi/scsi_priv.h

@@ -29,6 +29,7 @@ extern int scsi_init_hosts(void);
 extern void scsi_exit_hosts(void);
 
 /* scsi.c */
+extern bool scsi_use_blk_mq;
 extern int scsi_setup_command_freelist(struct Scsi_Host *shost);
 extern void scsi_destroy_command_freelist(struct Scsi_Host *shost);
 #ifdef CONFIG_SCSI_LOGGING

include/scsi/scsi_host.h

@@ -771,12 +771,9 @@ static inline int scsi_host_in_recovery(struct Scsi_Host *shost)
 		shost->tmf_in_progress;
 }
 
-extern bool scsi_use_blk_mq;
-
 static inline bool shost_use_blk_mq(struct Scsi_Host *shost)
 {
-	return scsi_use_blk_mq;
-
+	return shost->use_blk_mq;
 }
 
 extern int scsi_queue_work(struct Scsi_Host *, struct work_struct *);