From bb1d23b02657f494dff295f6cdd1f29df30fa61e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 5 Jul 2005 15:00:32 -0700 Subject: [PATCH] [IPV4]: Bug fix in rt_check_expire() - rt_check_expire() fixes (an overflow occured if size of the hash was >= 65536) reminder of the bugfix: The rt_check_expire() has a serious problem on machines with large route caches, and a standard HZ value of 1000. With default values, ie ip_rt_gc_interval = 60*HZ = 60000 ; the loop count : for (t = ip_rt_gc_interval << rt_hash_log; t >= 0; overflows (t is a 31 bit value) as soon rt_hash_log is >= 16 (65536 slots in route cache hash table). In this case, rt_check_expire() does nothing at all Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/route.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 9fcbb1b0a8d6..726ea5e8180a 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -54,7 +54,7 @@ * Marc Boucher : routing by fwmark * Robert Olsson : Added rt_cache statistics * Arnaldo C. Melo : Convert proc stuff to seq_file - * Eric Dumazet : hashed spinlocks + * Eric Dumazet : hashed spinlocks and rt_check_expire() fixes. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -606,18 +606,25 @@ static struct rtable **rt_remove_balanced_route(struct rtable **chain_head, /* This runs via a timer and thus is always in BH context. */ static void rt_check_expire(unsigned long dummy) { - static int rover; - int i = rover, t; + static unsigned int rover; + unsigned int i = rover, goal; struct rtable *rth, **rthp; unsigned long now = jiffies; - - for (t = ip_rt_gc_interval << rt_hash_log; t >= 0; - t -= ip_rt_gc_timeout) { + u64 mult; + + mult = ((u64)ip_rt_gc_interval) << rt_hash_log; + if (ip_rt_gc_timeout > 1) + do_div(mult, ip_rt_gc_timeout); + goal = (unsigned int)mult; + if (goal > rt_hash_mask) goal = rt_hash_mask + 1; + for (; goal > 0; goal--) { unsigned long tmo = ip_rt_gc_timeout; i = (i + 1) & rt_hash_mask; rthp = &rt_hash_table[i].chain; + if (*rthp == 0) + continue; spin_lock(rt_hash_lock_addr(i)); while ((rth = *rthp) != NULL) { if (rth->u.dst.expires) { @@ -658,7 +665,7 @@ static void rt_check_expire(unsigned long dummy) break; } rover = i; - mod_timer(&rt_periodic_timer, now + ip_rt_gc_interval); + mod_timer(&rt_periodic_timer, jiffies + ip_rt_gc_interval); } /* This can run from both BH and non-BH contexts, the latter -- 2.20.1