From 30c9afa6cc477f6f21f8a0b36f3b81080941a0c9 Mon Sep 17 00:00:00 2001 From: Joe Eykholt Date: Mon, 15 Jun 2009 23:22:14 -0700 Subject: [PATCH] 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 --- drivers/scsi/hosts.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) 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 */ -- 2.39.5