From: Joe Eykholt Date: Tue, 16 Jun 2009 06:22:14 +0000 (-0700) Subject: fix race that can give duplicate host number X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=30c9afa6cc477f6f21f8a0b36f3b81080941a0c9;p=deliverable%2Flinux.git 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 Signed-off-by: James Bottomley --- diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index 89d41a424b33..5fd2da494d08 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 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) 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 */