Andrew Morton wrote:

On Fri, 04 Dec 2009 11:23:14 -0500
Vlad Yasevich [off-list ref] wrote:

quoted

quoted

Overall, it would be way simpler and saner to clamp this value to some
explicit time period, IMO.

<pulls number out of thin air>

--- a/net/sctp/socket.c~a
+++ a/net/sctp/socket.c

@@ -2086,9 +2086,8 @@ static int sctp_setsockopt_autoclose(str
 		return -EINVAL;
 	if (copy_from_user(&sp->autoclose, optval, optlen))
 		return -EFAULT;
-	/* make sure it won't exceed MAX_SCHEDULE_TIMEOUT */
-	if (sp->autoclose > (MAX_SCHEDULE_TIMEOUT / HZ) )
-		sp->autoclose = MAX_SCHEDULE_TIMEOUT / HZ ;
+	/* make sure it won't exceed one hour */
+	sp->autoclose = min_t(u32, sp->autoclose, 60 * 60);
 

But that may not be long enough.  The spec doesn't impose limits
and it's really up to the application to decide how long it wants
to keep idle connections open.  Thus any limits shorter the maximum
supported by kernel are really artificial and may not be sufficient.

Could make ->autoclose a u64?  That fixes any 32bit-vs-64bit
inconsistencies and allows for an effectively infinite period.

That's isn't going to help much since the timer intervals are unsigned longs,
and would overflow on 32 bit systems.  We would still need the limiting value to
prevent that overflow, but would be able to drop the cast.  Additionally, the
API provides only for a 32 bit integer, thus we would waste 32 bit of space.

I don't think that's worth it.  The last patch from Andrei fixed the warning
with a cast to u32.  It seems like the simplest solution.

-vlad