cvs commit: src/sys/alpha/alpha machdep.c trap.c src/sys/arm/arm machdep.c undefined.c src/sys/fs/pseudofs pseudofs_vnops.c src/sys/i386/linux linux_ptrace.c src/sys/ia64/ia64 machdep.c src/sys/kern kern_exit.c kern_kse.c sys_process.c src/sys/sys ...

[John Baldwin]

jhb         2006-02-22 18:57:50 UTC

  FreeBSD src repository

  Modified files:
    sys/alpha/alpha      machdep.c trap.c 
    sys/arm/arm          machdep.c undefined.c 
    sys/fs/pseudofs      pseudofs_vnops.c 
    sys/i386/linux       linux_ptrace.c 
    sys/ia64/ia64        machdep.c 
    sys/kern             kern_exit.c kern_kse.c sys_process.c 
    sys/sys              proc.h 
  Log:
  Close some races between procfs/ptrace and exit(2):
  - Reorder the events in exit(2) slightly so that we trigger the S_EXIT
    stop event earlier.  After we have signalled that, we set P_WEXIT and
    then wait for any processes with a hold on the vmspace via PHOLD to
    release it.  PHOLD now KASSERT()'s that P_WEXIT is clear when it is
    invoked, and PRELE now does a wakeup if P_WEXIT is set and p_lock drops
    to zero.
  - Change proc_rwmem() to require that the processing read from has its
    vmspace held via PHOLD by the caller and get rid of all the junk to
    screw around with the vmspace reference count as we no longer need it.
  - In ptrace() and pseudofs(), treat a process with P_WEXIT set as if it
    doesn't exist.
  - Only do one PHOLD in kern_ptrace() now, and do it earlier so it covers
    FIX_SSTEP() (since on alpha at least this can end up calling proc_rwmem()
    to clear an earlier single-step simualted via a breakpoint).  We only
    do one to avoid races.  Also, by making the EINVAL error for unknown
    requests be part of the default: case in the switch, the various
    switch cases can now just break out to return which removes a _lot_ of
    duplicated PRELE and proc unlocks, etc.  Also, it fixes at least one bug
    where a LWP ptrace command could return EINVAL with the proc lock still
    held.
  - Changed the locking for ptrace_single_step(), ptrace_set_pc(), and
    ptrace_clear_single_step() to always be called with the proc lock
    held (it was a mixed bag previously).  Alpha and arm have to drop
    the lock while the mess around with breakpoints, but other archs
    avoid extra lock release/acquires in ptrace().  I did have to fix a
    couple of other consumers in kern_kse and a few other places to
    hold the proc lock and PHOLD.
  
  Tested by:      ps (1 mostly, but some bits of 2-4 as well)
  MFC after:      1 week
  
  Revision  Changes    Path
  1.238     +24 -3     src/sys/alpha/alpha/machdep.c
  1.129     +4 -0      src/sys/alpha/alpha/trap.c
  1.21      +15 -1     src/sys/arm/arm/machdep.c
  1.11      +4 -0      src/sys/arm/arm/undefined.c
  1.59      +8 -0      src/sys/fs/pseudofs/pseudofs_vnops.c
  1.17      +6 -0      src/sys/i386/linux/linux_ptrace.c
  1.207     +2 -0      src/sys/ia64/ia64/machdep.c
  1.285     +22 -5     src/sys/kern/kern_exit.c
  1.223     +16 -2     src/sys/kern/kern_kse.c
  1.137     +60 -104   src/sys/kern/sys_process.c
  1.454     +3 -0      src/sys/sys/proc.h