Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 04/17] ptrace: relocate set_current_state(TASK_TRACED) in ptrace_stop() | Date | Mon, 30 May 2011 01:12:27 +0200 |
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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> --- 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); -- 1.7.5.2
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