Skip to content

L
linux

xiphi1978 / linux

通知 2
Star 0
Fork 0
L
linux

体验新版 GitCode，发现更多精彩内容 >>

切换分支/标签
  1. 30 9月, 2006 1 次提交
  3. 27 9月, 2006 2 次提交
  5. 28 8月, 2006 1 次提交
    • D
      [PATCH] fix up lockdep trace in fs/exec.c · 513627d7
      由 Dave Jones 提交于 
      This fixes the locking error noticed by lockdep:

  =============================================
  [ INFO: possible recursive locking detected ]
  ---------------------------------------------
  init/1 is trying to acquire lock:
   (&sighand->siglock){....}, at: [<c047a78a>] flush_old_exec+0x3ae/0x859

  but task is already holding lock:
   (&sighand->siglock){....}, at: [<c047a77a>] flush_old_exec+0x39e/0x859

  other info that might help us debug this:
  2 locks held by init/1:
   #0:  (tasklist_lock){..--}, at: [<c047a76a>] flush_old_exec+0x38e/0x859
   #1:  (&sighand->siglock){....}, at: [<c047a77a>] flush_old_exec+0x39e/0x859

  stack backtrace:
   [<c04051e1>] show_trace_log_lvl+0x54/0xfd
   [<c040579d>] show_trace+0xd/0x10
   [<c04058b6>] dump_stack+0x19/0x1b
   [<c043b33a>] __lock_acquire+0x773/0x997
   [<c043bacf>] lock_acquire+0x4b/0x6c
   [<c060630b>] _spin_lock+0x19/0x28
   [<c047a78a>] flush_old_exec+0x3ae/0x859
   [<c0498053>] load_elf_binary+0x4aa/0x1628
   [<c0479cab>] search_binary_handler+0xa7/0x24e
   [<c047b577>] do_execve+0x15b/0x1f9
   [<c04022b4>] sys_execve+0x29/0x4d
   [<c0403faf>] syscall_call+0x7/0xb
Signed-off-by: NArjan van de Ven <arjan@infradead.org>
Signed-off-by: NDave Jones <davej@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      513627d7
  7. 25 8月, 2006 2 次提交
  9. 01 7月, 2006 1 次提交
  11. 27 6月, 2006 8 次提交
  13. 23 6月, 2006 1 次提交
    • M
      [PATCH] remove steal_locks() · c89681ed
      由 Miklos Szeredi 提交于 
      This patch removes the steal_locks() function.

steal_locks() doesn't work correctly with any filesystem that does it's own
lock management, including NFS, CIFS, etc.

In addition it has weird semantics on local filesystems in case tasks
sharing file-descriptor tables are doing POSIX locking operations in
parallel to execve().

The steal_locks() function has an effect on applications doing:

clone(CLONE_FILES)
  /* in child */
  lock
  execve
  lock

POSIX locks acquired before execve (by "child", "parent" or any further
task sharing files_struct) will after the execve be owned exclusively by
"child".

According to Chris Wright some LSB/LTP kind of suite triggers without the
stealing behavior, but there's no known real-world application that would
also fail.

Apps using NPTL are not affected, since all other threads are killed before
execve.

Apps using LinuxThreads are only affected if they

  - have multiple threads during exec (LinuxThreads doesn't kill other
    threads, the app may do it with pthread_kill_other_threads_np())
  - rely on POSIX locks being inherited across exec

Both conditions are documented, but not their interaction.

Apps using clone() natively are affected if they

  - use clone(CLONE_FILES)
  - rely on POSIX locks being inherited across exec

The above scenarios are unlikely, but possible.

If the patch is vetoed, there's a plan B, that involves mostly keeping the
weird stealing semantics, but changing the way lock ownership is handled so
that network and local filesystems work consistently.

That would add more complexity though, so this solution seems to be
preferred by most people.
Signed-off-by: NMiklos Szeredi <miklos@szeredi.hu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      c89681ed
  15. 20 6月, 2006 1 次提交
  17. 20 4月, 2006 1 次提交
  19. 14 4月, 2006 1 次提交
    • E
      [PATCH] de_thread: Don't change our parents and ptrace flags. · c06511d1
      由 Eric W. Biederman 提交于 
      This is two distinct changes.
 - Not changing our real parents.
 - Not changing our ptrace parents.

Not changing our real parents is trivially correct because both tasks
have the same real parents as they are part of a thread group.  Now that
we demote the leader to a thread there is no longer any reason to change
it's parentage.

Not changing our ptrace parents is a user visible change if someone
looks hard enough.  I don't think user space applications will care or
even notice.

In the practical and I think common case a debugger will have attached
to all of the threads using the same ptrace flags.  From my quick skim
of strace and gdb that appears to be the case.  Which if true means
debuggers will not notice a change.

Before this point we have already generated a ptrace event in do_exit
that reports the leaders pid has died so de_thread is visible to a
debugger.  Which means attempting to hide this case by copying flags
around appears excessive.

By not doing anything it avoids all of the weird locking issues between
de_thread and ptrace attach, and removes one case from consideration for
fixing the ptrace locking.

This only addresses Oleg's first concern with ptrace_attach, that of the
problems caused by reparenting.  Oleg's second concern is essentially a
race between ptrace_attach and release_task that causes an oops when we
get to force_sig_specific.  There is nothing special about de_thread
with respect to that race.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      c06511d1
  21. 11 4月, 2006 2 次提交
    • R
      [PATCH] process accounting: take original leader's start_time in non-leader exec · f5e90281
      由 Roland McGrath 提交于 
      The only record we have of the real-time age of a process, regardless of
execs it's done, is start_time.  When a non-leader thread exec, the
original start_time of the process is lost.  Things looking at the
real-time age of the process are fooled, for example the process accounting
record when the process finally dies.  This change makes the oldest
start_time stick around with the process after a non-leader exec.  This way
the association between PID and start_time is kept constant, which seems
correct to me.
Signed-off-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      f5e90281
    • E
      [PATCH] de_thread: Don't confuse users do_each_thread. · de12a787
      由 Eric W. Biederman 提交于 
      Oleg Nesterov spotted two interesting bugs with the current de_thread
code.  The simplest is a long standing double decrement of
__get_cpu_var(process_counts) in __unhash_process.  Caused by
two processes exiting when only one was created.

The other is that since we no longer detach from the thread_group list
it is possible for do_each_thread when run under the tasklist_lock to
see the same task_struct twice.  Once on the task list as a
thread_group_leader, and once on the thread list of another
thread.

The double appearance in do_each_thread can cause a double increment
of mm_core_waiters in zap_threads resulting in problems later on in
coredump_wait.

To remedy those two problems this patch takes the simple approach
of changing the old thread group leader into a child thread.
The only routine in release_task that cares is __unhash_process,
and it can be trivially seen that we handle cleaning up a
thread group leader properly.

Since de_thread doesn't change the pid of the exiting leader process
and instead shares it with the new leader process.  I change
thread_group_leader to recognize group leadership based on the
group_leader field and not based on pids.  This should also be
slightly cheaper then the existing thread_group_leader macro.

I performed a quick audit and I couldn't see any user of
thread_group_leader that cared about the difference.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      de12a787
  23. 01 4月, 2006 1 次提交
  25. 29 3月, 2006 5 次提交
    • O
      [PATCH] convert sighand_cache to use SLAB_DESTROY_BY_RCU · aa1757f9
      由 Oleg Nesterov 提交于 
      This patch borrows a clever Hugh's 'struct anon_vma' trick.

Without tasklist_lock held we can't trust task->sighand until we locked it
and re-checked that it is still the same.

But this means we don't need to defer 'kmem_cache_free(sighand)'.  We can
return the memory to slab immediately, all we need is to be sure that
sighand->siglock can't dissapear inside rcu protected section.

To do so we need to initialize ->siglock inside ctor function,
SLAB_DESTROY_BY_RCU does the rest.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      aa1757f9
    • O
      [PATCH] remove add_parent()'s parent argument · 8fafabd8
      由 Oleg Nesterov 提交于 
      add_parent(p, parent) is always called with parent == p->parent, and it makes
no sense to do it differently.  This patch removes this argument.

No changes in affected .o files.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      8fafabd8
    • E
      [PATCH] pidhash: kill switch_exec_pids · d73d6529
      由 Eric W. Biederman 提交于 
      switch_exec_pids is only called from de_thread by way of exec, and it is
only called when we are exec'ing from a non thread group leader.

Currently switch_exec_pids gives the leader the pid of the thread and
unhashes and rehashes all of the process groups.  The leader is already in
the EXIT_DEAD state so no one cares about it's pids.  The only concern for
the leader is that __unhash_process called from release_task will function
correctly.  If we don't touch the leader at all we know that
__unhash_process will work fine so there is no need to touch the leader.

For the task becomming the thread group leader, we just need to give it the
pid of the old thread group leader, add it to the task list, and attach it
to the session and the process group of the thread group.

Currently de_thread is also adding the task to the task list which is just
silly.

Currently the only leader of __detach_pid besides detach_pid is
switch_exec_pids because of the ugly extra work that was being
performed.

So this patch removes switch_exec_pids because it is doing too much, it is
creating an unnecessary special case in pid.c, duing work duplicated in
de_thread, and generally obscuring what it is going on.

The necessary work is added to de_thread, and it seems to be a little
clearer there what is going on.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      d73d6529
    • O
      [PATCH] simplify exec from init's subthread · 1434261c
      由 Oleg Nesterov 提交于 
      I think it is enough to take tasklist_lock for reading while changing
child_reaper:

	Reparenting needs write_lock(tasklist_lock)

	Only one thread in a thread group can do exec()

	sighand->siglock garantees that get_signal_to_deliver()
	will not see a stale value of child_reaper.

This means that we can change child_reaper earlier, without calling
zap_other_threads() twice.

"child_reaper = current" is a NOOP when init does exec from main thread, we
don't care.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      1434261c
    • E
      [PATCH] exec: allow init to exec from any thread. · fef23e7f
      由 Eric W. Biederman 提交于 
      After looking at the problem of init calling exec some more I figured out
an easy way to make the code work.

The actual symptom without out this patch is that all threads will die
except pid == 1, and the thread calling exec.  The thread calling exec will
wait forever for pid == 1 to die.

Since pid == 1 does not install a handler for SIGKILL it will never die.

This modifies the tests for init from current->pid == 1 to the equivalent
current == child_reaper.  And then it causes exec in the ugly case to
modify child_reaper.

The only weird symptom is that you wind up with an init process that
doesn't have the oldest start time on the box.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      fef23e7f
  27. 27 3月, 2006 1 次提交
  29. 26 3月, 2006 2 次提交
  31. 01 3月, 2006 1 次提交
  33. 16 2月, 2006 1 次提交
  35. 19 1月, 2006 1 次提交
    • U
      [PATCH] vfs: *at functions: core · 5590ff0d
      由 Ulrich Drepper 提交于 
      Here is a series of patches which introduce in total 13 new system calls
which take a file descriptor/filename pair instead of a single file
name.  These functions, openat etc, have been discussed on numerous
occasions.  They are needed to implement race-free filesystem traversal,
they are necessary to implement a virtual per-thread current working
directory (think multi-threaded backup software), etc.

We have in glibc today implementations of the interfaces which use the
/proc/self/fd magic.  But this code is rather expensive.  Here are some
results (similar to what Jim Meyering posted before).

The test creates a deep directory hierarchy on a tmpfs filesystem.  Then
rm -fr is used to remove all directories.  Without syscall support I get
this:

real    0m31.921s
user    0m0.688s
sys     0m31.234s

With syscall support the results are much better:

real    0m20.699s
user    0m0.536s
sys     0m20.149s

The interfaces are for obvious reasons currently not much used.  But they'll
be used.  coreutils (and Jeff's posixutils) are already using them.
Furthermore, code like ftw/fts in libc (maybe even glob) will also start using
them.  I expect a patch to make follow soon.  Every program which is walking
the filesystem tree will benefit.
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      5590ff0d
  37. 15 1月, 2006 1 次提交
  39. 11 1月, 2006 1 次提交
  41. 09 1月, 2006 3 次提交
    • O
      [PATCH] do_coredump() should reset group_stop_count earlier · bb6f6dba
      由 Oleg Nesterov 提交于 
      __group_complete_signal() sets ->group_stop_count in sig_kernel_coredump()
path and marks the target thread as ->group_exit_task.  So any thread
except group_exit_task will go to handle_group_stop()->finish_stop().

However, when group_exit_task actually starts do_coredump(), it sets
SIGNAL_GROUP_EXIT, but does not reset ->group_stop_count while killing
other threads.  If we have not yet stopped threads in the same thread
group, they all will spin in kernel mode until group_exit_task sends them
SIGKILL, because ->group_stop_count > 0 means:

	recalc_sigpending_tsk() never clears TIF_SIGPENDING

	get_signal_to_deliver() goes to handle_group_stop()

	handle_group_stop() returns when SIGNAL_GROUP_EXIT set

	syscall_exit/resume_userspace notice TIF_SIGPENDING,
	call get_signal_to_deliver() again.

So we are wasting cpu cycles, and if one of these threads is rt_task() this
may be a serious problem.

NOTE: do_coredump() holds ->mmap_sem, so not stopped threads can't escape
coredumping after clearing ->group_stop_count.

See also this thread: http://marc.theaimsgroup.com/?t=112739139900002Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      bb6f6dba
    • N
      [PATCH] Fix some problems with truncate and mtime semantics. · 4a30131e
      由 NeilBrown 提交于 
      SUS requires that when truncating a file to the size that it currently
is:
  truncate and ftruncate should NOT modify ctime or mtime
  O_TRUNC SHOULD modify ctime and mtime.

Currently mtime and ctime are always modified on most local
filesystems (side effect of ->truncate) or never modified (on NFS).

With this patch:
  ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when
    an update of these times is required whether size changes or not
    (via a new argument to do_truncate).  This allows NFS to do
    the right thing for O_TRUNC.
  inode_setattr nolonger forces ATTR_MTIME|ATTR_CTIME when the ATTR_SIZE
    sets the size to it's current value.  This allows local filesystems
    to do the right thing for f?truncate.

Also, the logic in inode_setattr is changed a bit so there are two return
points.  One returns the error from vmtruncate if it failed, the other
returns 0 (there can be no other failure).

Finally, if vmtruncate succeeds, and ATTR_SIZE is the only change
requested, we now fall-through and mark_inode_dirty.  If a filesystem did
not have a ->truncate function, then vmtruncate will have changed i_size,
without marking the inode as 'dirty', and I think this is wrong.
Signed-off-by: NNeil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      4a30131e
    • I
      [PATCH] RCU signal handling · e56d0903
      由 Ingo Molnar 提交于 
      RCU tasklist_lock and RCU signal handling: send signals RCU-read-locked
instead of tasklist_lock read-locked.  This is a scalability improvement on
SMP and a preemption-latency improvement under PREEMPT_RCU.
Signed-off-by: NPaul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NWilliam Irwin <wli@holomorphy.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      e56d0903
  43. 07 1月, 2006 1 次提交
  45. 30 11月, 2005 1 次提交