Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 07/19] ptrace: use bit_waitqueue for TRAPPING instead of wait_chldexit | Date | Tue, 24 May 2011 20:37:27 +0200 |
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ptracer->signal->wait_chldexit was used to wait for TRAPPING; however, ->wait_chldexit was already complicated with waker-side filtering without adding TRAPPING wait on top of it. Also, it unnecessarily made TRAPPING clearing depend on the current ptrace relationship - if the ptracee is detached, wakeup is lost.
There is no reason to use signal->wait_chldexit here. We're just waiting for JOBCTL_TRAPPING bit to clear and given the relatively infrequent use of ptrace, bit_waitqueue can serve it perfectly.
This patch makes JOBCTL_TRAPPING wait use bit_waitqueue instead of signal->wait_chldexit.
Signed-off-by: Tejun Heo <tj@kernel.org> --- kernel/ptrace.c | 10 ++++++++-- kernel/signal.c | 3 +-- 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index b44dc43..3be5d1b 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -25,6 +25,12 @@ #include <linux/hw_breakpoint.h> +static int ptrace_trapping_sleep_fn(void *flags) +{ + schedule(); + return 0; +} + /* * ptrace a task: make the debugger its new parent and * move it to the ptrace list. @@ -273,8 +279,8 @@ unlock_creds: mutex_unlock(&task->signal->cred_guard_mutex); out: if (wait_trap) - wait_event(current->signal->wait_chldexit, - !(task->jobctl & JOBCTL_TRAPPING)); + wait_on_bit(&task->jobctl, ilog2(JOBCTL_TRAPPING), + ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE); return retval; } diff --git a/kernel/signal.c b/kernel/signal.c index 17feedf..106b47e 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -272,8 +272,7 @@ static void task_clear_jobctl_trapping(struct task_struct *task) { if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { task->jobctl &= ~JOBCTL_TRAPPING; - __wake_up_sync_key(&task->parent->signal->wait_chldexit, - TASK_UNINTERRUPTIBLE, 1, task); + wake_up_bit(&task->jobctl, ilog2(JOBCTL_TRAPPING)); } } -- 1.7.1
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