W dniu 2017-09-21 o 03:17, Eric Dumazet pisze:
On Wed, 2017-09-20 at 18:09 -0700, Wei Wang wrote:
Thanks very much Pawel for the feedback.
I was looking into the code (specifically IPv4 part) and found that in
free_fib_info_rcu(), we call free_nh_exceptions() without holding the
fnhe_lock. I am wondering if that could cause some race condition on
fnhe->fnhe_rth_input/output so a double call on dst_dev_put() on the
same dst could be happening.
But as we call free_fib_info_rcu() only after the grace period, and
the lookup code which could potentially modify
fnhe->fnhe_rth_input/output all holds rcu_read_lock(), it seems
fine...
Hi Pawel,
Could you try the following debug patch on top of net-next branch and
reproduce the issue check if there are warning msg showing?
diff --git a/include/net/dst.h b/include/net/dst.h
index 93568bd0a352..82aff41c6f63 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -271,7 +271,7 @@ static inline void dst_use_noref(struct dst_entry
*dst, unsigned long time)
static inline struct dst_entry *dst_clone(struct dst_entry *dst)
{
if (dst)
- atomic_inc(&dst->__refcnt);
+ dst_hold(dst);
return dst;
}
Thanks.
Wei
Yes, we believe skb_dst_force() and skb_dst_force_safe() should be
unified (to the 'safe' version)
We no longer have gc to protect from 0 -> 1 transition of dst refcount.
After adding patch from Wei
https://bugzilla.kernel.org/show_bug.cgi?id=197005#c14
