Merge pull request torvalds#274 from liuyuan10/fix

lkl: Fix race condition on sched_jb
laijs · Nov 22, 2016 · 861cf05 · 861cf05
2 parents ac79c65 + 7a62de5
commit 861cf05
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Showing 4 changed files with 12 additions and 13 deletions.
diff --git a/arch/lkl/include/asm/sched.h b/arch/lkl/include/asm/sched.h
@@ -17,11 +17,6 @@ static inline void thread_sched_jb(void)
 	}
 }
 
-static inline void thread_set_sched_exit(void)
-{
-	set_ti_thread_flag(current_thread_info(), TIF_SCHED_EXIT);
-}
-
 void switch_to_host_task(struct task_struct *);
 
 #endif /*  _ASM_LKL_SCHED_H */
diff --git a/arch/lkl/include/asm/thread_info.h b/arch/lkl/include/asm/thread_info.h
@@ -59,9 +59,8 @@ void threads_cnt_dec(void);
 #define TIF_MEMDIE			5
 #define TIF_NOHZ			6
 #define TIF_SCHED_JB			7
-#define TIF_SCHED_EXIT			8
-#define TIF_HOST_THREAD			9
-#define TIF_IDLE			10
+#define TIF_HOST_THREAD			8
+#define TIF_IDLE			9
 
 #define __HAVE_THREAD_FUNCTIONS
 

diff --git a/arch/lkl/kernel/syscalls.c b/arch/lkl/kernel/syscalls.c
@@ -75,18 +75,23 @@ static int new_host_task(struct task_struct **task)
 
 	return 0;
 }
+static void exit_task(void)
+{
+	do_exit(0);
+}
 
 static void del_host_task(void *arg)
 {
 	struct task_struct *task = (struct task_struct *)arg;
+	struct thread_info *ti = task_thread_info(task);
 
 	if (lkl_cpu_get() < 0)
 		return;
 
 	switch_to_host_task(task);
 	host_task_id--;
-	thread_set_sched_exit();
-	do_exit(0);
+	set_ti_thread_flag(ti, TIF_SCHED_JB);
+	lkl_ops->jmp_buf_set(&ti->sched_jb, exit_task);
 }
 
 static struct lkl_tls_key *task_key;

diff --git a/arch/lkl/kernel/threads.c b/arch/lkl/kernel/threads.c
@@ -93,6 +93,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
 	unsigned long _prev_flags = _prev->flags;
 	bool wakeup_idle = test_bit(TIF_IDLE, &_next->flags) &&
 				lkl_cpu_idle_pending();
+	struct lkl_jmp_buf _prev_jb;
 
 	_current_thread_info = task_thread_info(next);
 	_next->prev_sched = prev;
@@ -103,6 +104,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
 	if (test_bit(TIF_SCHED_JB, &_prev_flags)) {
 		/* Atomic. Must be done before wakeup next */
 		clear_ti_thread_flag(_prev, TIF_SCHED_JB);
+		_prev_jb = _prev->sched_jb;
 	}
 	if (wakeup_idle)
 		schedule_tail(abs_prev);
@@ -115,9 +117,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
 		lkl_ops->sem_up(_next->sched_sem);
 
 	if (test_bit(TIF_SCHED_JB, &_prev_flags)) {
-		lkl_ops->jmp_buf_longjmp(&_prev->sched_jb, 1);
-	} else if (test_bit(TIF_SCHED_EXIT, &_prev_flags)) {
-		lkl_ops->thread_exit();
+		lkl_ops->jmp_buf_longjmp(&_prev_jb, 1);
 	} else {
 		lkl_ops->sem_down(_prev->sched_sem);
 	}