[PATCH] syscall: Implement a convinience function restart_syscall

[ebiederm@xmission.com (Eric W. Biederman)]

Currently when we have a signal pending we have the functionality
to restart that the current system call.  There are other cases
such as nasty lock ordering issues where it makes sense to have
a simple fix that uses try lock and restarts the system call.
Buying time to figure out how to rework the locking strategy.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
 include/linux/sched.h |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b4c38bc..d853f6b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2178,6 +2178,12 @@ static inline int test_tsk_need_resched(struct task_struct *tsk)
 	return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
 }
 
+static inline int restart_syscall(void)
+{
+	set_tsk_thread_flag(current, TIF_SIGPENDING);
+	return -ERESTARTNOINTR;
+}
+
 static inline int signal_pending(struct task_struct *p)
 {
 	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
-- 
1.6.0.6