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

[Douglas Gilbert <dougg@torque.net>]

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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



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--- 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;