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author | Tejun Heo <tj@kernel.org> | 2011-06-02 11:13:59 +0200 |
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committer | Oleg Nesterov <oleg@redhat.com> | 2011-06-04 18:17:10 +0200 |
commit | 81be24b8cdeb69e62f9d1b6b425fd9ffdd37f581 (patch) | |
tree | 63afd141fdb380c7b00a01a2080ace6bcc232386 /kernel/signal.c | |
parent | 755e276b3326f300585435d2f3876e66e248c476 (diff) | |
download | kernel_goldelico_gta04-81be24b8cdeb69e62f9d1b6b425fd9ffdd37f581.zip kernel_goldelico_gta04-81be24b8cdeb69e62f9d1b6b425fd9ffdd37f581.tar.gz kernel_goldelico_gta04-81be24b8cdeb69e62f9d1b6b425fd9ffdd37f581.tar.bz2 |
ptrace: relocate set_current_state(TASK_TRACED) in ptrace_stop()
In ptrace_stop(), after arch hook is done, the task state and jobctl
bits are updated while holding siglock. The ordering requirement
there is that TASK_TRACED is set before JOBCTL_TRAPPING is cleared to
prevent ptracer waiting on TRAPPING doesn't end up waking up TRACED is
actually set and sees TASK_RUNNING in wait(2).
Move set_current_state(TASK_TRACED) to the top of the block and
reorganize comments. This makes the ordering more obvious
(TASK_TRACED before other updates) and helps future updates to group
stop participation.
This patch doesn't cause any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r-- | kernel/signal.c | 28 |
1 files changed, 13 insertions, 15 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index ab6851c..62a6c3b 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1733,6 +1733,18 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) } /* + * We're committing to trapping. TRACED should be visible before + * TRAPPING is cleared; otherwise, the tracer might fail do_wait(). + * Also, transition to TRACED and updates to ->jobctl should be + * atomic with respect to siglock and should be done after the arch + * hook as siglock is released and regrabbed across it. + */ + set_current_state(TASK_TRACED); + + current->last_siginfo = info; + current->exit_code = exit_code; + + /* * If @why is CLD_STOPPED, we're trapping to participate in a group * stop. Do the bookkeeping. Note that if SIGCONT was delievered * while siglock was released for the arch hook, PENDING could be @@ -1742,21 +1754,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING)) gstop_done = task_participate_group_stop(current); - current->last_siginfo = info; - current->exit_code = exit_code; - - /* - * TRACED should be visible before TRAPPING is cleared; otherwise, - * the tracer might fail do_wait(). - */ - set_current_state(TASK_TRACED); - - /* - * We're committing to trapping. Clearing JOBCTL_TRAPPING and - * transition to TASK_TRACED should be atomic with respect to - * siglock. This should be done after the arch hook as siglock is - * released and regrabbed across it. - */ + /* entering a trap, clear TRAPPING */ task_clear_jobctl_trapping(current); spin_unlock_irq(¤t->sighand->siglock); |