[ 05/22] ptrace: introduce signal_wake_up_state() and ptrace_signal_wake_up()

From: Greg Kroah-Hartman
Date: Thu Jan 24 2013 - 16:27:10 EST


3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Oleg Nesterov <oleg@xxxxxxxxxx>

commit 910ffdb18a6408e14febbb6e4b6840fd2c928c82 upstream.

Cleanup and preparation for the next change.

signal_wake_up(resume => true) is overused. None of ptrace/jctl callers
actually want to wakeup a TASK_WAKEKILL task, but they can't specify the
necessary mask.

Turn signal_wake_up() into signal_wake_up_state(state), reintroduce
signal_wake_up() as a trivial helper, and add ptrace_signal_wake_up()
which adds __TASK_TRACED.

This way ptrace_signal_wake_up() can work "inside" ptrace_request()
even if the tracee doesn't have the TASK_WAKEKILL bit set.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
include/linux/sched.h | 11 ++++++++++-
kernel/ptrace.c | 8 ++++----
kernel/signal.c | 14 ++++----------
3 files changed, 18 insertions(+), 15 deletions(-)

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2695,7 +2695,16 @@ static inline void thread_group_cputime_
extern void recalc_sigpending_and_wake(struct task_struct *t);
extern void recalc_sigpending(void);

-extern void signal_wake_up(struct task_struct *t, int resume_stopped);
+extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
+
+static inline void signal_wake_up(struct task_struct *t, bool resume)
+{
+ signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
+}
+static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
+{
+ signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
+}

/*
* Wrappers for p->thread_info->cpu access. No-op on UP.
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -117,7 +117,7 @@ void __ptrace_unlink(struct task_struct
* TASK_KILLABLE sleeps.
*/
if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
- signal_wake_up(child, task_is_traced(child));
+ ptrace_signal_wake_up(child, true);

spin_unlock(&child->sighand->siglock);
}
@@ -311,7 +311,7 @@ static int ptrace_attach(struct task_str
*/
if (task_is_stopped(task) &&
task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
- signal_wake_up(task, 1);
+ signal_wake_up_state(task, __TASK_STOPPED);

spin_unlock(&task->sighand->siglock);

@@ -728,7 +728,7 @@ int ptrace_request(struct task_struct *c
* tracee into STOP.
*/
if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
- signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
+ ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);

unlock_task_sighand(child, &flags);
ret = 0;
@@ -754,7 +754,7 @@ int ptrace_request(struct task_struct *c
* start of this trap and now. Trigger re-trap.
*/
if (child->jobctl & JOBCTL_TRAP_NOTIFY)
- signal_wake_up(child, true);
+ ptrace_signal_wake_up(child, true);
ret = 0;
}
unlock_task_sighand(child, &flags);
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -677,23 +677,17 @@ int dequeue_signal(struct task_struct *t
* No need to set need_resched since signal event passing
* goes through ->blocked
*/
-void signal_wake_up(struct task_struct *t, int resume)
+void signal_wake_up_state(struct task_struct *t, unsigned int state)
{
- unsigned int mask;
-
set_tsk_thread_flag(t, TIF_SIGPENDING);
-
/*
- * For SIGKILL, we want to wake it up in the stopped/traced/killable
+ * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
* case. We don't check t->state here because there is a race with it
* executing another processor and just now entering stopped state.
* By using wake_up_state, we ensure the process will wake up and
* handle its death signal.
*/
- mask = TASK_INTERRUPTIBLE;
- if (resume)
- mask |= TASK_WAKEKILL;
- if (!wake_up_state(t, mask))
+ if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
kick_process(t);
}

@@ -842,7 +836,7 @@ static void ptrace_trap_notify(struct ta
assert_spin_locked(&t->sighand->siglock);

task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
- signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
+ ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
}

/*


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