Re: Problem: strace -ff fails on 2.4.21-rc1

[Chuck Ebbert]

> Another note: suid is ignored when you are tracing the task which runs
> exec() for a setuid program.

  You're right -- an ordinary user cannot trace minicom's setgroupid
children with -ff (but root now can, where with rc1 that failed too.)

  And this is no longer an strace/ptrace problem at all.

  Minicom hangs on exit (ctrl-a, q, enter) even when strace is not
running (can't believe I just now thought to try that.)

minicom       S C01183A1  4472  1197    834                     (NOTLB)
Using defaults from ksymoops -t elf32-i386 -a i386
Call Trace:    [<c0122f24>] [<c0134a31>] [<c021195b>] [<c0220d79>] [<c020d997>]
  [<c011690d>] [<c020e01a>] [<c013c52e>] [<c013b1d5>] [<c013b23b>] [<c0108b73>]
Warning (Oops_read): Code line not seen, dumping what data is available

Proc;  minicom
>>EIP; c01183a1 <schedule+351/3b0>   <===== ignore this bogus address
Trace; c0122f24 <schedule_timeout+14/a0>
Trace; c0134a31 <__alloc_pages+41/170>
Trace; c021195b <tty_wait_until_sent+9b/e0>
Trace; c0220d79 <rs_close+129/1f0>
Trace; c020d997 <release_dev+247/500>
Trace; c011690d <do_page_fault+11d/43b>
Trace; c020e01a <tty_release+2a/60>
Trace; c013c52e <fput+4e/100>
Trace; c013b1d5 <filp_close+95/a0>
Trace; c013b23b <sys_close+5b/70>
Trace; c0108b73 <system_call+33/38>

It's hung up somewhere inside schedule().