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Date:      Sat, 9 Dec 2000 14:01:58 -0500 (EST)
From:      Kenneth Wayne Culver <culverk@wam.umd.edu>
To:        freebsd-questions@freebsd.org
Subject:   kernel panic in 4.2 with AHA-2940
Message-ID:  <Pine.GSO.4.21.0012091356290.26508-100000@rac4.wam.umd.edu>

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Alright, since nobody is answering me in the freebsd-scsi list about my
4.2 panic with the AHA-2940, I'll send this here. I have gotten the crash
again, and in addition to that, I have the panic messages, a backtrace and
what I think is happening. I can send whoever needs it my vmcore.0,
kernel.0, and kernel.debug if you want

(kgdb) bt   
#0  dumpsys () at ../../kern/kern_shutdown.c:469
#1  0xc014c22f in boot (howto=260) at ../../kern/kern_shutdown.c:309
#2  0xc014c5c5 in panic (fmt=0xc02229b4 "from debugger")
    at ../../kern/kern_shutdown.c:556
#3  0xc012a055 in db_panic (addr=-1072224404, have_addr=0, count=-1, 
    modif=0xcd4b2c28 "") at ../../ddb/db_command.c:433
#4  0xc0129ff5 in db_command (last_cmdp=0xc024f5ec, cmd_table=0xc024f44c, 
    aux_cmd_tablep=0xc0289d08) at ../../ddb/db_command.c:333
#5  0xc012a0ba in db_command_loop () at ../../ddb/db_command.c:455
#6  0xc012c1c7 in db_trap (type=12, code=0) at ../../ddb/db_trap.c:71
#7  0xc0203826 in kdb_trap (type=12, code=0, regs=0xcd4b2d7c)
    at ../../i386/i386/db_interface.c:158
#8  0xc020fa10 in trap_fatal (frame=0xcd4b2d7c, eva=152)
    at ../../i386/i386/trap.c:946
#9  0xc020f6e9 in trap_pfault (frame=0xcd4b2d7c, usermode=0, eva=152)
    at ../../i386/i386/trap.c:844
#10 0xc020f28b in trap (frame={tf_fs = 16, tf_es = 16, tf_ds = 16, 
      tf_edi = -850353856, tf_esi = -850710760, tf_ebp = -850711096, 
      tf_isp = -850711128, tf_ebx = 128, tf_edx = -1061277696, 
      tf_ecx = -861838324, tf_eax = 683, tf_trapno = 12, tf_err = 0, 
      tf_eip = -1072224404, tf_cs = 8, tf_eflags = 66054, tf_esp = 0, 
      tf_ss = -850353856}) at ../../i386/i386/trap.c:443
#11 0xc017276c in cache_lookup (dvp=0xcd50a140, vpp=0xcd4b2f04,
cnp=0xcd4b2f18)
    at ../../kern/vfs_cache.c:213
#12 0xc0172c08 in vfs_cache_lookup (ap=0xcd4b2e58)
    at ../../kern/vfs_cache.c:451
#13 0xc01b8e51 in ufs_vnoperate (ap=0xcd4b2e58)
    at ../../ufs/ufs/ufs_vnops.c:2287
---Type <return> to continue, or q <return> to quit---
#14 0xc0175b50 in lookup (ndp=0xcd4b2ef0) at vnode_if.h:52
#15 0xc0175640 in namei (ndp=0xcd4b2ef0) at ../../kern/vfs_lookup.c:153
#16 0xc017ae25 in access (p=0xcca02ea0, uap=0xcd4b2f80)
    at ../../kern/vfs_syscalls.c:1599
#17 0xc020fc5e in syscall2 (frame={tf_fs = 47, tf_es = 47, tf_ds = 47, 
      tf_edi = 134524429, tf_esi = 134522776, tf_ebp = -1077939796, 
      tf_isp = -850710572, tf_ebx = 134524416, tf_edx = -1, tf_ecx = 2, 
      tf_eax = 33, tf_trapno = 12, tf_err = 2, tf_eip = 671749180, tf_cs =
31, 
      tf_eflags = 643, tf_esp = -1077939840, tf_ss = 47})
    at ../../i386/i386/trap.c:1150
#18 0xc0204165 in Xint0x80_syscall ()

I looked at what caused the trap and it seems to be in the line

                if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen
&&
                    !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
                        break;

I think it is because ncp->nc_name has a value:

(kgdb) print ncp->nc_name
$7 = 0x804ae00 "admindefines"

but cnp->cn_nameptr is a null pointer:

(kgdb) print cnp->cn_nameptr
$8 = 0x0

but the length argument to bcmp is:

(kgdb) print ncp->nc_nlen
$9 = 73 'I'

I don't know where to go from here though, I have absolutely no idea why
cnp->cn_nameptr would be NULL, or how any of this could be caused 
by the SCSI driver, but I know it is the ahc driver's fault
because when I take that driver out of the kernel, everything
works fine again. Anyway, any help is appreciated.

Ken




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