Date: Tue, 9 Nov 2004 20:40:21 GMT From: Maxim Konovalov <maxim@FreeBSD.org> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/73719: Page fault in bpf_mtap () Message-ID: <200411092040.iA9KeL8i012078@freefall.freebsd.org>
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The following reply was made to PR kern/73719; it has been noted by GNATS. From: Maxim Konovalov <maxim@FreeBSD.org> To: Vladimir Ivanov <wawa@yandex-team.ru> Cc: rwatson@FreeBSD.org, bug-followup@FreeBSD.org Subject: Re: kern/73719: Page fault in bpf_mtap () Date: Tue, 9 Nov 2004 23:35:41 +0300 (MSK) On Tue, 9 Nov 2004, 20:10-0000, Vladimir Ivanov wrote: > The following reply was made to PR kern/73719; it has been noted by GNATS. > > From: Vladimir Ivanov <wawa@yandex-team.ru> > To: freebsd-gnats-submit@FreeBSD.org, wawa@yandex-team.ru > Cc: > Subject: Re: kern/73719: Page fault in bpf_mtap () > Date: Tue, 09 Nov 2004 23:02:26 +0300 > > Ok, > The bpf_mtap () seems to be little enough to make a look. > > We suppose that most probable reason to panic is zero value of "bp" pointer. > Also, I know that bpf open/close are frequent on my system. > We can see (look at BPF_MTAP definition) that the value may be changed > from another thread after verification but before bpf_mtap call because > "ifp" points to global variable. The patch does not change the logic of > program as you can see but garantee "bp" is not NULL. The only side > effect is hypotetic pushing extra packet to just detached bpf device. > It's not very big price I seem > > I've commited the patch to the system and awaiting results. I can't believe this technique is a right way to fix things. Robert, is bpf(4) MP safe already? -- Maxim Konovalov
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