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Date:      Tue, 25 May 1999 21:09:02 -0400
From:      "David E. Cross" <crossd@cs.rpi.edu>
To:        hackers@freebsd.org
Subject:   kernel debugging assistance
Message-ID:  <199905260109.VAA93769@cs.rpi.edu>

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I am trying to trace down the cause of the recursive lock and I stumbled upon
this:

(kgdb) bt
#0  boot (howto=256) at ../../kern/kern_shutdown.c:285
#1  0xc014b3f4 in at_shutdown (
    function=0xc0234aca <__set_sysuninit_set_sym_M_KTRACE_uninit_sys_uninit+154>, arg=0x10002, queue=-951064448) at ../../kern/kern_shutdown.c:446
#2  0xc01470f8 in lockmgr (lkp=0xc10d8f00, flags=16842754, 
    interlkp=0xc74fe8f0, p=0xc743eb20) at ../../kern/kern_lock.c:326
#3  0xc016cfbc in vop_stdlock (ap=0xc7482a64) at ../../kern/vfs_default.c:209
#4  0xc01e4fad in ufs_vnoperate (ap=0xc7482a64)
    at ../../ufs/ufs/ufs_vnops.c:2299
#5  0xc0175d97 in vn_lock (vp=0xc74fe880, flags=65538, p=0xc743eb20)
    at vnode_if.h:811
#6  0xc016f93f in vget (vp=0xc74fe880, flags=2, p=0xc743eb20)
    at ../../kern/vfs_subr.c:1274
#7  0xc016bac7 in vfs_cache_lookup (ap=0xc7482b24)
    at ../../kern/vfs_cache.c:439
#8  0xc01e4fad in ufs_vnoperate (ap=0xc7482b24)
    at ../../ufs/ufs/ufs_vnops.c:2299
#9  0xc016e079 in lookup (ndp=0xc7482d94) at vnode_if.h:31
#10 0xc01b769c in nfs_namei (ndp=0xc7482d94, fhp=0xc7482d0c, len=3, 
    slp=0xc0f7e600, nam=0xc0f54200, mdp=0xc7482c48, dposp=0xc7482c44, 
    retdirp=0xc7482c2c, p=0xc743eb20, kerbflag=0, pubflag=0)
    at ../../nfs/nfs_subs.c:1642
#11 0xc01a068f in nfsrv_lookup (nfsd=0xc1185700, slp=0xc0f7e600, 
    procp=0xc743eb20, mrq=0xc7482e34) at ../../nfs/nfs_serv.c:396
#12 0xc01b90f6 in nfssvc_nfsd (nsd=0xc7482e94, argp=0x8071af4 "", p=0xc743eb20)
    at ../../nfs/nfs_syscalls.c:656
#13 0xc01b8a11 in nfssvc (p=0xc743eb20, uap=0xc7482f94)
    at ../../nfs/nfs_syscalls.c:342
#14 0xc020bd5f in syscall (frame={tf_es = 39, tf_ds = 39, tf_edi = 8, 
      tf_esi = 0, tf_ebp = -1077944892, tf_isp = -951570460, tf_ebx = 0, 
      tf_edx = -1077945288, tf_ecx = 0, tf_eax = 155, tf_trapno = 12, 
      tf_err = 2, tf_eip = 134518940, tf_cs = 31, tf_eflags = 642, 
      tf_esp = -1077945280, tf_ss = 39}) at ../../i386/i386/trap.c:1100
#15 0xc0202b8c in Xint0x80_syscall ()
#16 0x80480e9 in ?? ()
(kgdb) up 3
#3  0xc016cfbc in vop_stdlock (ap=0xc7482a64) at ../../kern/vfs_default.c:209
209             return (lockmgr(l, ap->a_flags, &ap->a_vp->v_interlock, ap->a_p));
(kgdb) print ap
$1 = (struct vop_lock_args *) 0x0
(kgdb) 

That doesn't seem to be possible, especially since ap->FOO is used in the same
line.. wouldn't that cause a fault at this point? (it isn't the panic
occurs later as you can see.)

--
David Cross                               |  email: crossd@cs.rpi.edu 
Systems Administrator/Research Programmer |  Web: http://www.cs.rpi.edu/~crossd 
Rensselaer Polytechnic Institute,         |  Ph: 518.276.2860            
Department of Computer Science            |  Fax: 518.276.4033
I speak only for myself.                  |  WinNT:Linux::Linux:FreeBSD


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