Date: Mon, 04 Jun 2012 10:48:38 +0400 From: "Alexander V. Chernikov" <melifaro@FreeBSD.org> To: Andriy Gapon <avg@FreeBSD.org> Cc: freebsd-net@FreeBSD.org, FreeBSD-Current <freebsd-current@FreeBSD.org> Subject: Re: null pointer panic in bpf_peers_present Message-ID: <4FCC5A46.8020007@FreeBSD.org> In-Reply-To: <4FCBE3B6.1020003@FreeBSD.org> References: <4FCBCF7E.9020603@FreeBSD.org> <4FCBE3B6.1020003@FreeBSD.org>
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On 04.06.2012 02:22, Andriy Gapon wrote:
> on 03/06/2012 23:56 Andriy Gapon said the following:
>>
>> I wonder if anybody else is seeing this and if there is a fix...
>> This is very recent (today's) FreeBSD head with pretty dull network
>> configuration. During boot I run into the following panic:
>>
>> <118>Setting hostname: xxxxx
>> <118>Starting dhclient.
>>
> My current guess is that the panic occurs because of the newly added (r235745)
> bpf_ifdetach which is an ifnet_departure_event handler. My rc.conf is
> configured to do interface renaming and SIOCSIFNAME seems to post
> ifnet_departure_event followed by ifnet_arrival_event.
>
> Not sure if it's a window between ifnet_departure_event and ifnet_arrival_event
> when if_bpf is NULL, or if if_bpf is never restored in this case.
if_bpf is never restored.
Can you please try an attached patch ?
>>
>
>
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Index: sys/net/bpf.c
===================================================================
--- sys/net/bpf.c (revision 236540)
+++ sys/net/bpf.c (working copy)
@@ -2542,13 +2542,23 @@ bpf_ifdetach(void *arg __unused, struct ifnet *ifp
{
struct bpf_if *bp;
- if ((bp = ifp->if_bpf) == NULL)
+ BPF_LOCK();
+ if ((bp = ifp->if_bpf) == NULL) {
+ BPF_UNLOCK();
return;
+ }
+ if ((bp->flags & BPFIF_FLAG_DYING) == 0) {
+ BPF_UNLOCK();
+ return;
+ }
+
CTR3(KTR_NET, "%s: freing BPF instance %p for interface %p",
__func__, bp, ifp);
ifp->if_bpf = NULL;
+ BPF_UNLOCK();
+
rw_destroy(&bp->bif_lock);
free(bp, M_BPF);
}
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