Re: [PATCH 1/2] ipv6: do not hold route table lock when send ndisc probe
From: Debabrata Banerjee <hidden>
Date: 2012-08-17 18:54:26
Well it get rids of the deadlock for sure, but I am not sure it doesn't break something else, one would have to know all of this code much better to tell. You'll notice read_unlock_bh(&table->tb6_lock) for the first lock in ip6_pol_route() has more in the critical section after the rt6_select() call, especially that rather scary BACKTRACK() macro. -Debabrata On Fri, Aug 17, 2012 at 3:11 AM, Cong Wang [off-list ref] wrote:
quoted hunk ↗ jump to hunk
In rt6_probe(), we call ndisc_send_ns() with root->rwlock, but this is not necessary, so we can drop it before calling ndisc_send_ns(). This could probably fix the deadlock reported by Debabrata: https://lkml.org/lkml/2012/8/16/432 Reported-by: "Banerjee, Debabrata" <redacted> Cc: "Banerjee, Debabrata" <redacted> Cc: "David S. Miller" <davem@davemloft.net> Cc: Hideaki YOSHIFUJI <redacted> Cc: Patrick McHardy <redacted> Signed-off-by: Cong Wang <redacted> --- net/ipv6/route.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-)diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 0ddf2d1..7a36df2 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c@@ -460,13 +460,18 @@ static void rt6_probe(struct rt6_info *rt) time_after(jiffies, neigh->updated + rt->rt6i_idev->cnf.rtr_probe_interval)) { struct in6_addr mcaddr; struct in6_addr *target; + struct net_device *dev = rt->dst.dev; + struct fib6_table *table = rt->rt6i_table; neigh->updated = jiffies; read_unlock_bh(&neigh->lock); + read_unlock_bh(&table->tb6_lock); target = (struct in6_addr *)&neigh->primary_key; addrconf_addr_solict_mult(target, &mcaddr); - ndisc_send_ns(rt->dst.dev, NULL, target, &mcaddr, NULL); + ndisc_send_ns(dev, NULL, target, &mcaddr, NULL); + + read_lock_bh(&table->tb6_lock); } else { read_unlock_bh(&neigh->lock); } --1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html