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core kernel fixes for v3.7

GIT PULL Ingo Molnar 1 participant 1 message Oct 1, 2012

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Ingo Molnar

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Linus,

Please pull the latest core-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-for-linus

HEAD: f784e8a7989c0da3062d04bfea3db90f41e8f738 task_work: Simplify the usage in ptrace_notify() and get_signal_to_deliver()

This is a complex task_work series from Oleg that fixes the bug that this VFS commit tried to fix:

d35abdb28824 hold task_lock around checks in keyctl

but solves the problem without the lockup regression that d35abdb28824 introduced in v3.6.

This series came late in v3.6 and I did not feel confident about it so late in the cycle. Might be worth backporting to -stable if it proves itself upstream.

Thanks,

Ingo

------------------>
Oleg Nesterov (4):
task_work: Make task_work_add() lockless
task_work: task_work_add() should not succeed after exit_task_work()
task_work: Revert "hold task_lock around checks in keyctl"
task_work: Simplify the usage in ptrace_notify() and get_signal_to_deliver()

 include/linux/task_work.h |   3 +-
 kernel/signal.c           |  18 ++------
 kernel/task_work.c        | 111 +++++++++++++++++++++++++---------------------
 security/keys/keyctl.c    |   2 -
 4 files changed, 66 insertions(+), 68 deletions(-)
include/linux/task_work.h +1 -2
index fb46b03..ca5a1cf 100644
@@ -18,8 +18,7 @@ void task_work_run(void);
 
 static inline void exit_task_work(struct task_struct *task)
 {
-	if (unlikely(task->task_works))
-		task_work_run();
+	task_work_run();
 }
 
 #endif	/* _LINUX_TASK_WORK_H */
kernel/signal.c +4 -14
index be4f856..2c681f1 100644
@@ -1971,13 +1971,8 @@ static void ptrace_do_notify(int signr, int exit_code, int why)
 void ptrace_notify(int exit_code)
 {
 	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
-	if (unlikely(current->task_works)) {
-		if (test_and_clear_ti_thread_flag(current_thread_info(),
-						   TIF_NOTIFY_RESUME)) {
-			smp_mb__after_clear_bit();
-			task_work_run();
-		}
-	}
+	if (unlikely(current->task_works))
+		task_work_run();
 
 	spin_lock_irq(&current->sighand->siglock);
 	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);

@@ -2198,13 +2193,8 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 	struct signal_struct *signal = current->signal;
 	int signr;
 
-	if (unlikely(current->task_works)) {
-		if (test_and_clear_ti_thread_flag(current_thread_info(),
-						   TIF_NOTIFY_RESUME)) {
-			smp_mb__after_clear_bit();
-			task_work_run();
-		}
-	}
+	if (unlikely(current->task_works))
+		task_work_run();
 
 	if (unlikely(uprobe_deny_signal()))
 		return 0;
kernel/task_work.c +61 -50

139 lines not on this page · raw message

security/keys/keyctl.c +0 -2
index 3364fbf..6cfc647 100644
@@ -1486,7 +1486,6 @@ long keyctl_session_to_parent(void)
 	oldwork = NULL;
 	parent = me->real_parent;
 
-	task_lock(parent);
 	/* the parent mustn't be init and mustn't be a kernel thread */
 	if (parent->pid <= 1 || !parent->mm)
 		goto unlock;

@@ -1530,7 +1529,6 @@ long keyctl_session_to_parent(void)
 	if (!ret)
 		newwork = NULL;
 unlock:
-	task_unlock(parent);
 	write_unlock_irq(&tasklist_lock);
 	rcu_read_unlock();
 	if (oldwork)