| Message ID | 1340388785.4604.11442.camel@edumazet-glaptop |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Fri, Jun 22, 2012 at 2:13 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > On Fri, 2012-06-22 at 08:44 -0500, Josh Hunt wrote: > >> Ahh. That makes sense and is what Alexey said before I just didn't put >> it all together. So we are OK reverting this patch? I cannot find a path >> where the walker's pointers are updated without the tb6_lock write_lock. >> > > There was a bug somewhere, not sure we want to NULL dereference again. > As you identified, the tree seems to be protected by tb6_lock. I couldn't find a race by inspection either. If this is not the root of the problem, how would this patch fix it? So I think it does nothing. We are attempting to reproduce that crash to prove it, but like Gao feng I don't think we will see it. My current favorite theory is that inet6_dump_fib was called with a NULL func in callback. This looks like the approximate area of the crash, but it's impossible to say without more information from Patrick McHardy. -- 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
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Fri, 22 Jun 2012 20:13:05 +0200 > On Fri, 2012-06-22 at 08:44 -0500, Josh Hunt wrote: > >> Ahh. That makes sense and is what Alexey said before I just didn't put >> it all together. So we are OK reverting this patch? I cannot find a path >> where the walker's pointers are updated without the tb6_lock write_lock. >> > > There was a bug somewhere, not sure we want to NULL dereference again. Well: 1) Patrick McHardy has been inactive for a while, so do not expect any insight from him. 2) Ben Greear isn't even on the CC: list of this discussion yet he appears to be the person who reproduced the crash way back then and is listed in the Tested-by tag of the commit. As a result we aren't likely to get any insight from the one person who actually could hit the crash. I'm inclined to just revert simply because we have people active who can reproduce regressions introduced by this change and nobody can understand why the change is even necessary. -- 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
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 74c21b9..6083276 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -1349,8 +1349,8 @@ static int fib6_walk_continue(struct fib6_walker_t *w) if (w->leaf && fn->fn_flags & RTN_RTINFO) { int err; - if (w->count < w->skip) { - w->count++; + if (w->skip) { + w->skip--; continue; }