[NET] Fix too aggressive backoff in dst garbage collection
The bug is evident when it is seen once. dst gc timer was backed off,
when gc queue is not empty. But this means that timer quickly backs off,
if at least one destination remains in use. Normally, the bug is invisible,
because adding new dst entry to queue cancels the backoff. But it shots
deadly with destination cache overflow when new destinations are not released
for long time f.e. after an interface goes down.
The fix is to cancel backoff when something was released.
Signed-off-by: Denis Lunev <den@sw.ru>
Signed-off-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dst.c b/net/core/dst.c
index fc434ad..334790d 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -45,6 +45,7 @@
static void dst_run_gc(unsigned long dummy)
{
int delayed = 0;
+ int work_performed;
struct dst_entry * dst, **dstp;
if (!spin_trylock(&dst_lock)) {
@@ -52,9 +53,9 @@
return;
}
-
del_timer(&dst_gc_timer);
dstp = &dst_garbage_list;
+ work_performed = 0;
while ((dst = *dstp) != NULL) {
if (atomic_read(&dst->__refcnt)) {
dstp = &dst->next;
@@ -62,6 +63,7 @@
continue;
}
*dstp = dst->next;
+ work_performed = 1;
dst = dst_destroy(dst);
if (dst) {
@@ -86,9 +88,14 @@
dst_gc_timer_inc = DST_GC_MAX;
goto out;
}
- if ((dst_gc_timer_expires += dst_gc_timer_inc) > DST_GC_MAX)
- dst_gc_timer_expires = DST_GC_MAX;
- dst_gc_timer_inc += DST_GC_INC;
+ if (!work_performed) {
+ if ((dst_gc_timer_expires += dst_gc_timer_inc) > DST_GC_MAX)
+ dst_gc_timer_expires = DST_GC_MAX;
+ dst_gc_timer_inc += DST_GC_INC;
+ } else {
+ dst_gc_timer_inc = DST_GC_INC;
+ dst_gc_timer_expires = DST_GC_MIN;
+ }
dst_gc_timer.expires = jiffies + dst_gc_timer_expires;
#if RT_CACHE_DEBUG >= 2
printk("dst_total: %d/%d %ld\n",