fix race that can give duplicate host number
Just once, two fcoe instances got the same host number
from scsi_add_host().
Use atomic_t and atomic_inc_return() to get next host number.
Subtract 1, so that scsi_host still starts with 0.
[jejb: added comment about unusual subtraction]
Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 89d41a4..5fd2da4 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -40,7 +40,7 @@
#include "scsi_logging.h"
-static int scsi_host_next_hn; /* host_no for next new host */
+static atomic_t scsi_host_next_hn; /* host_no for next new host */
static void scsi_host_cls_release(struct device *dev)
@@ -333,7 +333,11 @@
mutex_init(&shost->scan_mutex);
- shost->host_no = scsi_host_next_hn++; /* XXX(hch): still racy */
+ /*
+ * subtract one because we increment first then return, but we need to
+ * know what the next host number was before increment
+ */
+ shost->host_no = atomic_inc_return(&scsi_host_next_hn) - 1;
shost->dma_channel = 0xff;
/* These three are default values which can be overridden */