>Number:         12534
>Category:       kern
>Synopsis:       Processes can hang at exit-time on ttyout
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Apr 03 01:27:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Antti Kantee
>Release:        1.5.1_ALPHA
>Organization:
>Environment:
System: NetBSD 1.5.1_ALPHA i386

>Description:

Under some conditions an exiting process can hang in the kernel:

zhora:1:~> ps axl
  UID   PID  PPID CPU PRI  NI    VSZ   RSS WCHAN    STAT TT     TIME COMMAND
26645  9966     1   0   4   0    200   532 ttyout   IE   p0- 0:00.01 (uisp)

I have figured out nothing that helps short of a reboot.

Inside the kernel the process traceback looks like this:
#0  mi_switch (p=0xf6740010) at ../../../../kern/kern_synch.c:834
#1  0xc0134cfe in ltsleep (ident=0xf637e164, priority=282, 
    wmesg=0xc028f263 "ttyout", timo=0, interlock=0x0)
    at ../../../../kern/kern_synch.c:482
#2  0xc0144c66 in ttysleep (tp=0xf637e11c, chan=0xf637e164, pri=282, 
    wmesg=0xc028f263 "ttyout", timo=0) at ../../../../kern/tty.c:2121
#3  0xc0143633 in ttywait (tp=0xf637e11c) at ../../../../kern/tty.c:1085
#4  0xc014367a in ttywflush (tp=0xf637e11c) at ../../../../kern/tty.c:1102
#5  0xc01438d2 in ttylclose (tp=0xf637e11c, flag=3)
    at ../../../../kern/tty.c:1223
#6  0xc0105ace in comclose (dev=2048, flag=3, mode=8192, p=0xf6740010)
    at ../../../../dev/ic/com.c:905
#7  0xc01651a6 in spec_close (v=0xf71a4e4c)
    at ../../../../miscfs/specfs/spec_vnops.c:653
#8  0xc0221ac1 in ufsspec_close (v=0xf71a4e4c)
    at ../../../../ufs/ufs/ufs_vnops.c:1758
#9  0xc015c557 in vn_close (vp=0xf69fe948, flags=3, cred=0xc0dd7580, 
    p=0xf6740010) at ../../../../sys/vnode_if.h:171
#10 0xc015ce07 in vn_closefile (fp=0xf671fe74, p=0xf6740010)
    at ../../../../kern/vfs_vnops.c:605
#11 0xc012b73a in closef (fp=0xf671fe74, p=0xf6740010)
    at ../../../../kern/kern_descrip.c:1090
#12 0xc012b56d in fdfree (p=0xf6740010) at ../../../../kern/kern_descrip.c:965
---Type <return> to continue, or q <return> to quit---
#13 0xc012d1a2 in exit1 (p=0xf6740010, rv=2)
    at ../../../../kern/kern_exit.c:185
#14 0xc01333bb in sigexit (p=0xf6740010, signum=2)
    at ../../../../kern/kern_sig.c:1281
#15 0xc01331ba in postsig (signum=2) at ../../../../kern/kern_sig.c:1178
#16 0xc023a0f2 in syscall (frame={tf_es = 31, tf_ds = 31, 
      tf_edi = -1077946988, tf_esi = 1, tf_ebp = -1077957156, 
      tf_ebx = -1077957188, tf_edx = 3404, tf_ecx = 4, tf_eax = 4, 
      tf_trapno = 3, tf_err = 2, tf_eip = 1209026483, tf_cs = 23, 
      tf_eflags = 519, tf_esp = -1077957320, tf_ss = 31, tf_vm86_es = 0, 
      tf_vm86_ds = 0, tf_vm86_fs = 0, tf_vm86_gs = 0})
    at ../../../../arch/i386/i386/trap.c:187
#17 0xc0100cab in syscall1 ()

Here's one from another process which seems to be suffering from the
same problem:

#0  mi_switch (p=0xf66a8980) at ../../../../kern/kern_synch.c:834
#1  0xc0134cfe in ltsleep (ident=0xf637e5d4, priority=282, 
    wmesg=0xc028f263 "ttyout", timo=0, interlock=0x0)
    at ../../../../kern/kern_synch.c:482
#2  0xc0144c66 in ttysleep (tp=0xf637e58c, chan=0xf637e5d4, pri=282, 
    wmesg=0xc028f263 "ttyout", timo=0) at ../../../../kern/tty.c:2121
#3  0xc0143633 in ttywait (tp=0xf637e58c) at ../../../../kern/tty.c:1085
#4  0xc014367a in ttywflush (tp=0xf637e58c) at ../../../../kern/tty.c:1102
#5  0xc01438d2 in ttylclose (tp=0xf637e58c, flag=3)
    at ../../../../kern/tty.c:1223
#6  0xc0144fa5 in ptsclose (dev=1282, flag=3, mode=8192, p=0xf66a8980)
    at ../../../../kern/tty_pty.c:173
#7  0xc01651a6 in spec_close (v=0xf6dd7e4c)
    at ../../../../miscfs/specfs/spec_vnops.c:653
#8  0xc0221ac1 in ufsspec_close (v=0xf6dd7e4c)
    at ../../../../ufs/ufs/ufs_vnops.c:1758
#9  0xc015c557 in vn_close (vp=0xf6a52d0c, flags=3, cred=0xc0bb6f80, 
    p=0xf66a8980) at ../../../../sys/vnode_if.h:171
#10 0xc015ce07 in vn_closefile (fp=0xf671ff34, p=0xf66a8980)
    at ../../../../kern/vfs_vnops.c:605
#11 0xc012b73a in closef (fp=0xf671ff34, p=0xf66a8980)
    at ../../../../kern/kern_descrip.c:1090
#12 0xc012b56d in fdfree (p=0xf66a8980) at ../../../../kern/kern_descrip.c:965
---Type <return> to continue, or q <return> to quit---
#13 0xc012d1a2 in exit1 (p=0xf66a8980, rv=9)
    at ../../../../kern/kern_exit.c:185
#14 0xc01333bb in sigexit (p=0xf66a8980, signum=9)
    at ../../../../kern/kern_sig.c:1281
#15 0xc01331ba in postsig (signum=9) at ../../../../kern/kern_sig.c:1178
#16 0xc023a0f2 in syscall (frame={tf_es = 43, tf_ds = 43, tf_edi = 134736144, 
      tf_esi = 10, tf_ebp = -1077963604, tf_ebx = 10, tf_edx = 17, 
      tf_ecx = 135339784, tf_eax = 4, tf_trapno = 3, tf_err = 2, 
      tf_eip = 1209121465, tf_cs = 35, tf_eflags = 514, tf_esp = -1077963620, 
      tf_ss = 43, tf_vm86_es = 0, tf_vm86_ds = 0, tf_vm86_fs = 0, 
      tf_vm86_gs = 0}) at ../../../../arch/i386/i386/trap.c:187
#17 0xc0100cab in syscall1 ()

Especially notice frame #6!

>How-To-Repeat:

Not sure. Run eg. com port using processes until the problem shows up.

>Fix:

don't know
>Release-Note:
>Audit-Trail:
>Unformatted: