Re: panic: mutex Giant not owned at src/sys/security/mac/mac_net.c:355

On 2004.04.22 17:19:32 -0400, Robert Watson wrote:
> 
> On Thu, 22 Apr 2004, Simon L. Nielsen wrote:
> 
> > I have a reproduceable panic when I have MAC enabled in my kernel and I
> > try to run tcpdump on the interface I have logged in on via ssh (I'm not
> > really sure why it only happens in this case and in other cases).  I run
> > "tcpdump -n -i sis0" and the panic as shown below.  I do not have any
> > MAC policies loaded. 
> > 
> > The problem is (if I understand the code correctly) that MAC calls
> > BPFD_LOCK_ASSERT, which rwatson added NET_ASSERT_GIANT to, but since the
> > sis interrupt handler is marked INTR_MPSAFE then GIANT isn't aquired
> > before bpf_mtap (and therefor mac_check_bpfdesc_receive) is called.
> > 
> > I'm not really sure what the correct fix is, but if bpf is locked, is
> > GIANT really required for it?
> 
> Are you running a main line kernel with debug.mpsafenet turned on?

Main line kernel (I assume you mean no special patches), but
debug.mpsafenet is turned off.

[root_at_soekris:~] sysctl debug.mpsafenet
debug.mpsafenet: 0

> > panic: mutex Giant not owned at /data/nanobsd/src/sys/security/mac/mac_net.c:355
> > at line 729 in file /data/nanobsd/src/sys/kern/kern_mutex.c
> > Debugger("panic")
> > Stopped at      Debugger+0x45:  xchgl   %ebx,in_Debugger.0
> > db> trace
> > Debugger(c063705f) at Debugger+0x45
> > __panic(c06363ea,2d9,c063655f,c063669a,c0646fff) at __panic+0xc7
> > _mtx_assert(c0689720,1,c0646fff,163) at _mtx_assert+0xc2
> > mac_check_bpfdesc_receive(c1995c00,c1750c00) at mac_check_bpfdesc_receive+0x40
> > bpf_mtap(c17536c0,c0adfa00) at bpf_mtap+0xa6
> > sis_start(c1750c00) at sis_start+0x1a7
> > sis_tick(c1750c00) at sis_tick+0x70
> > softclock(0) at softclock+0x176
> > ithread_loop(c0ac2500,c80c2d48,c0ac2500,c04c2e80,0) at ithread_loop+0x11c
> > fork_exit(c04c2e80,c0ac2500,c80c2d48) at fork_exit+0xa8
> > fork_trampoline() at fork_trampoline+0x8
> > --- trap 0x1, eip = 0, esp = 0xc80c2d7c, ebp = 0 ---

-- 
Simon L. Nielsen
FreeBSD Documentation Team