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authorTejun Heo <tj@kernel.org>2011-06-02 11:14:00 +0200
committerOleg Nesterov <oleg@redhat.com>2011-06-04 18:17:11 +0200
commit62c124ff3bcdb414af635c2bf822c9e4f2a5abfa (patch)
tree5d279211e098d24245d49e394d84aa8cfdb6f277 /kernel/ptrace.c
parent7dd3db54e77d21eb95e145f19ba53f68250d0e73 (diff)
downloadlinux-62c124ff3bcdb414af635c2bf822c9e4f2a5abfa.tar.bz2
ptrace: use bit_waitqueue for TRAPPING instead of wait_chldexit
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. -v2: Use JOBCTL_*_BIT macros instead of ilog2() as suggested by Linus. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r--kernel/ptrace.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 0c37d999c8b8..7f05f3a1267b 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.
@@ -270,8 +276,8 @@ unlock_creds:
mutex_unlock(&task->signal->cred_guard_mutex);
out:
if (!retval)
- wait_event(current->signal->wait_chldexit,
- !(task->jobctl & JOBCTL_TRAPPING));
+ wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
+ ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
return retval;
}