[34-longterm 255/260] sd name space exhaustion causes system hang

Paul Gortmaker
2011-01-02T07:28:51Z

From: Michael Reed <mdr@sgi.com>

commit 1a03ae0f556a931aa3747b70e44b78308f5b0590 upstream.

Following a site power outage which re-enabled all the ports on my FC
switches, my system subsequently booted with far too many luns! I had
let it run hoping it would make multi-user. It didn't. :( It hung solid
after exhausting the last sd device, sdzzz, and attempting to create sdaaaa
and beyond. I was unable to get a dump.

Discovered using a 2.6.32.13 based system.

correct this by detecting when the last index is utilized and failing
the sd probe of the device. Patch applies to scsi-misc-2.6.

Signed-off-by: Michael Reed <mdr@sgi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
drivers/scsi/sd.c | 15 ++++++++++-----
1 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index de6c603..892f446 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2163,11 +2163,10 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
index = sdkp->index;
dev = &sdp->sdev_gendev;

- if (index < SD_MAX_DISKS) {
- gd->major = sd_major((index & 0xf0) >> 4);
- gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
- gd->minors = SD_MINORS;
- }
+ gd->major = sd_major((index & 0xf0) >> 4);
+ gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
+ gd->minors = SD_MINORS;
+
gd->fops = &sd_fops;
gd->private_data = &sdkp->driver;
gd->queue = sdkp->device->request_queue;
@@ -2256,6 +2255,12 @@ static int sd_probe(struct device *dev)
if (error)
goto out_put;

+ if (index >= SD_MAX_DISKS) {
+ error = -ENODEV;
+ sdev_printk(KERN_WARNING, sdp, "SCSI disk (sd) name space exhausted.\n");
+ goto out_free_index;
+ }
+
error = sd_format_disk_name("sd", index, gd->disk_name, DISK_NAME_LEN);
if (error)
goto out_free_index;
--
1.7.3.3