sg kill local jiffies problems

sg kill local jiffies problems

[Douglas Gilbert]

It has been reported that the change to sg.c in lk 2.6.9-rc1-bk5
to use library jiffy functions breaks sg (albeit under vmware).
Evidentally sg devices are no longer recognised after that change.

Reverting that changeset removes the problem. Strange, it is not
obvious why.

At some stage I must have detected negative time spans (yeh yeh it
never happens) and my versions returned 0 in this case; otherwise
the implementations look very similar.

Doug Gilbert

[PATCH] sg jiffy library calls [was: sg kill local jiffies problems]

[Douglas Gilbert]

[-- Attachment #1: Type: text/plain, Size: 780 bytes --]

Douglas Gilbert wrote:
> It has been reported that the change to sg.c in lk 2.6.9-rc1-bk5
> to use library jiffy functions breaks sg (albeit under vmware).
> Evidentally sg devices are no longer recognised after that change.
> 
> Reverting that changeset removes the problem. Strange, it is not
> obvious why.
> 
> At some stage I must have detected negative time spans (yeh yeh it
> never happens) and my versions returned 0 in this case; otherwise
> the implementations look very similar.

The following patch fixes the problem. It is
against lk 2.6.9-rc1-bk7 (i.e. after "standard"
jiffy_to_millisecs macros replaced sg versions).

Change:
    - make sure a (large) user supplied timeout value does
      not result in a negative timeout passed to the midlevel

Doug Gilbert



[-- Attachment #2: sg_269rc1bk7jif.diff --]
[-- Type: text/x-patch, Size: 703 bytes --]

--- linux/drivers/scsi/sg.c	2004-09-01 11:48:55.000000000 +1000
+++ linux/drivers/scsi/sg.c269rc1bk7jif	2004-09-06 17:00:56.000000000 +1000
@@ -576,6 +576,7 @@
 	sg_io_hdr_t *hp;
 	unsigned char cmnd[sizeof (dummy_cmdp->sr_cmnd)];
 	int timeout;
+	unsigned long ul_timeout;
 
 	if (count < SZ_SG_IO_HDR)
 		return -EINVAL;
@@ -610,7 +611,8 @@
 			return -EBUSY;	/* reserve buffer already being used */
 		}
 	}
-	timeout = msecs_to_jiffies(srp->header.timeout);
+	ul_timeout = msecs_to_jiffies(srp->header.timeout);
+	timeout = (ul_timeout < INT_MAX) ? ul_timeout : INT_MAX;
 	if ((!hp->cmdp) || (hp->cmd_len < 6) || (hp->cmd_len > sizeof (cmnd))) {
 		sg_remove_request(sfp, srp);
 		return -EMSGSIZE;