lkml.org 
[lkml]   [2011]   [May]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 07/19] ptrace: use bit_waitqueue for TRAPPING instead of wait_chldexit
Date
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


\
 
 \ /
  Last update: 2011-05-24 20:41    [W:0.112 / U:0.124 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site