1. 12 Sep, 2002 1 commit
  2. 11 Sep, 2002 9 commits
    • Vojtech Pavlik's avatar
    • Linus Torvalds's avatar
      Allocate system call numbers: 250 and 251 for hugetlb, with · 0e9387ab
      Linus Torvalds authored
      252 for exit_group
      0e9387ab
    • Ingo Molnar's avatar
      [PATCH] Thread deadlock fix.. · 6ff3e5b7
      Ingo Molnar authored
      This fixes the old-pthreads breakage i can reproduce.
      
      the fix is to only do the thread-group exit-completion logic in case of
      thread-groups.
      6ff3e5b7
    • Ingo Molnar's avatar
      [PATCH] sys_exit_group(), threading, 2.5.34 · b62bf732
      Ingo Molnar authored
      This is another step to have better threading support under Linux, it
      implements the sys_exit_group() system call.
      
      It's a straightforward extension of the generic 'thread group' concept,
      which extension also comes handy to solve a number of problems when
      implementing POSIX threads.
      
      POSIX exit() [the C library function] has the following semantics: all
      thread have to exit and the waiting parent has to get the exit code that
      was specified for the exit() function.  It also has to be ensured that
      every thread has truly finished its work by the time the parent gets the
      notification.  The exit code has to be propagated properly to the parent
      thread even if not the thread group leader calls the exit() function.
      
      Normal single-thread exit is done via the pthread_exit() function, which
      calls sys_exit().
      
      Previous incarnations of Linux POSIX threads implementations chose the
      following solution: send a 'thread management' signal to the thread
      group leader via tkill(), which thread goes around and kills every
      thread in the group (except itself), then calls sys_exit() with the
      proper exit code.  Both old libpthreads and NGPT use this solution.
      
      This works to a certain degree, unless a userspace threading library
      uses the initial thread for normal thread work [like the new
      libpthreads], which 'work' can cause the initial thread to exit
      prematurely.
      
      At this point the threading library has to catch the group leader in
      pthread_exit() and has to keep the management thread 'hanging around'
      artificially, waiting for the management signal. Besides being slightly
      confusing to users ('why is this thread still around?') even this variant
      is unrobust: if the initial thread is killed by the kernel (SIGSEGV or any
      other thread-specific event that triggers do_exit()) then the thread goes
      away without the thread library having a chance to intervene.
      
      the sys_exit_group() syscall implements the mechanism within the kernel,
      which, besides robustness, is also *much* faster. Instead of the threading
      library having to tkill() every thread available, the kernel can use the
      already existing 'broadcast signal' capability. (the threading library
      cannot use broadcast signals because that would kill the initial thread as
      well.)
      
      as a side-effect of the completion mechanism used by sys_exit_group() it
      was also possible to make the initial thread hang around as a zombie until
      every other thread in the group has exited. A 'Z' state thread is much
      easier to understand by users - it's around because it has to wait for all
      other threads to exit first.
      
      and as a side-effect of the initial thread hanging around in a guaranteed
      way, there are three advantages:
      
       - signals sent to the thread group via sys_kill() work again. Previously
         if the initial thread exited then all subsequent sys_kill() calls to
         the group PID failed with a -ESRCH.
      
       - the get_pid() function got faster: it does not have to check for tgid
         collision anymore.
      
       - procps has an easier job displaying threaded applications - since the
         thread group leader is always around, no thread group can 'hide' from
         procps just because the thread group leader has exited.
      
       [ - NOTE: the same mechanism can/will also be used by the upcoming
           threaded-coredumps patch. ]
      
      there's also another (small) advantage for threading libraries: eg. the
      new libpthreads does not even have any notion of 'group of threads'
      anymore - it does not maintain any global list of threads. Via this
      syscall it can purely rely on the kernel to manage thread groups.
      
      the patch itself does some internal changes to the way a thread exits: now
      the unhashing of the PID and the signal-freeing is done atomically. This
      is needed to make sure the thread group leader unhashes itself precisely
      when the last thread group member has exited.
      
      (the sys_exit_group() syscall has been used by glibc's new libpthreads
      code for the past couple of weeks and the concept is working just fine.)
      b62bf732
    • Ingo Molnar's avatar
      [PATCH] exit.c compilation warning fix · 4c21fddc
      Ingo Molnar authored
      I forgot to remove an unused label in the deadlock fix patch.
      4c21fddc
    • Sam Ravnborg's avatar
      [PATCH] drivers/char/Makefile: Remove pty.o from export-objs · fb530c76
      Sam Ravnborg authored
      Remove pty.o from the export-objs list, since pty.c does not export
      any symbols.
      
      A /* EXPORT_SYMBOL */ comment may have fooled the original author.
      fb530c76
    • Sam Ravnborg's avatar
      [PATCH] zftape: Cleanup zftape_syms.c · a8b2e9c3
      Sam Ravnborg authored
      Removed compatibility cruft from zftape_syms.c.
      There is no need to be compatible with kernel 2.1.18 and older.
      Replaced FT_KSYM with direct call to EXPORT_SYMBOL.
      a8b2e9c3
    • Ivan Kokshaysky's avatar
      [PATCH] alpha update · e91208b7
      Ivan Kokshaysky authored
      - signal update; make do_signal use generic get_signal_to_deliver()
      - irqs_disabled macro
      - remove vmlinux.lds.s target from arch/alpha/Makefile since it works
        correctly in the top level Makefile
      - extra argument for pcibios_enable_device (most likely we'll never
        use it though...)
      e91208b7
    • Vojtech Pavlik's avatar
  3. 10 Sep, 2002 2 commits
    • Jens Axboe's avatar
      bio.h: · 6ebbf06b
      Jens Axboe authored
        clean up with bio_kmap_irq() thing properly. remove the micro optimization of _not_ calling kmap_atomic() if this isn't a highmem page. we could keep that and do the inc_preempt_count() ourselves, but I'm not sure it's worth it and this is cleaner.
      6ebbf06b
    • Jens Axboe's avatar
      Merge axboe@brick.kernel.dk:/mnt/kernel/ide/linux-2.5 · fe0e4341
      Jens Axboe authored
      into hera.kernel.org:/home/axboe/BK/linux-2.5-ide
      fe0e4341
  4. 11 Sep, 2002 28 commits