DragonFly-2.3.0.376.ge473f master sys/kern kern_sig.c sys/platform/pc32/i386 trap.c sys/platform/pc64/amd64 trap.c sys/platform/vkernel/i386 trap.c sys/sys signal2.h signalvar.h

[Simon Schubert <corecode@xxxxxxxxxxxxxxxxxxxxxxx>]

commit e473f7766f04bbc8db8b5f3762586fbaf2e18215
Author: Simon Schubert <corecode@dragonflybsd.org>
Date:   Sat Mar 7 18:09:13 2009 +0100

    signals: rework when CURSIG/issignal can stop a thread for tracing
    
    When tracing a process, it can happen that the thread would get stopped
    due to the signal and its tracing.  In this case the tracing parent
    would get notified and it might choose to let the process to serve the
    signal.
    
    However if this stop+trace is happening somewhere deep in the kernel due
    to a call to CURSIG(), it might happen that the same signal again is the
    cause for a stop+trace cycle because of another call to CURSIG() while
    the call stack is unwinding.
    
    Introduce CURSIG_TRACE(), which explicitly allows stopping for tracing
    signal delivery.  This is only called from userret().
    All other instances of CURSIG() may still block/sleep because of SA_STOP
    signals, but these invocations may not trace + repost signals.
    
    As such, the only place where trace + repost of signals can happen now
    is userret().  Nevertheless, CURSIG() still decides not to ignore a
    currently ignored signal and rather lets the kernel unwind until this
    signal arrives in the CURSIG_TRACE() called from userret().

Summary of changes:
 sys/kern/kern_sig.c              |   16 ++++++++++------
 sys/platform/pc32/i386/trap.c    |    2 +-
 sys/platform/pc64/amd64/trap.c   |    2 +-
 sys/platform/vkernel/i386/trap.c |    2 +-
 sys/sys/signal2.h                |    7 ++++---
 sys/sys/signalvar.h              |    2 +-
 6 files changed, 18 insertions(+), 13 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/e473f7766f04bbc8db8b5f3762586fbaf2e18215


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