[PATCH] posix-timers: Fix the flags handling in posix_cpu_nsleep()

When a posix_cpu_nsleep() sleep is interrupted by a signal more than twice, it
incorrectly reports the sleep time remaining to the user.  Because
posix_cpu_nsleep() doesn't report back to the user when it's called from
restart function due to the wrong flags handling.

This patch, which applies after previous one, moves the nanosleep() function
from posix_cpu_nsleep() to do_cpu_nanosleep() and cleans up the flags handling
appropriately.
Signed-off-by: Toyo Abe <toyoa@mvista.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/posix-cpu-timers.c

@@ -1393,22 +1393,12 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
 	}
 }
 
-int posix_cpu_nsleep(const clockid_t which_clock, int flags,
-		     struct timespec *rqtp, struct timespec __user *rmtp)
+static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
+			    struct timespec *rqtp, struct itimerspec *it)
 {
-	struct restart_block *restart_block =
-	    &current_thread_info()->restart_block;
 	struct k_itimer timer;
 	int error;
 
-	/*
-	 * Diagnose required errors first.
-	 */
-	if (CPUCLOCK_PERTHREAD(which_clock) &&
-	    (CPUCLOCK_PID(which_clock) == 0 ||
-	     CPUCLOCK_PID(which_clock) == current->pid))
-		return -EINVAL;
-
 	/*
 	 * Set up a temporary timer and then wait for it to go off.
 	 */
@@ -1420,11 +1410,12 @@ int posix_cpu_nsleep(const clockid_t which_clock, int flags,
 	timer.it_process = current;
 	if (!error) {
 		static struct itimerspec zero_it;
-		struct itimerspec it = { .it_value = *rqtp,
-					 .it_interval = {} };
+
+		memset(it, 0, sizeof *it);
+		it->it_value = *rqtp;
 
 		spin_lock_irq(&timer.it_lock);
-		error = posix_cpu_timer_set(&timer, flags, &it, NULL);
+		error = posix_cpu_timer_set(&timer, flags, it, NULL);
 		if (error) {
 			spin_unlock_irq(&timer.it_lock);
 			return error;
@@ -1452,33 +1443,56 @@ int posix_cpu_nsleep(const clockid_t which_clock, int flags,
 		 * We were interrupted by a signal.
 		 */
 		sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
-		posix_cpu_timer_set(&timer, 0, &zero_it, &it);
+		posix_cpu_timer_set(&timer, 0, &zero_it, it);
 		spin_unlock_irq(&timer.it_lock);
 
-		if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
+		if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
 			/*
 			 * It actually did fire already.
 			 */
 			return 0;
 		}
 
+		error = -ERESTART_RESTARTBLOCK;
+	}
+
+	return error;
+}
+
+int posix_cpu_nsleep(const clockid_t which_clock, int flags,
+		     struct timespec *rqtp, struct timespec __user *rmtp)
+{
+	struct restart_block *restart_block =
+	    &current_thread_info()->restart_block;
+	struct itimerspec it;
+	int error;
+
+	/*
+	 * Diagnose required errors first.
+	 */
+	if (CPUCLOCK_PERTHREAD(which_clock) &&
+	    (CPUCLOCK_PID(which_clock) == 0 ||
+	     CPUCLOCK_PID(which_clock) == current->pid))
+		return -EINVAL;
+
+	error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
+
+	if (error == -ERESTART_RESTARTBLOCK) {
+
+	       	if (flags & TIMER_ABSTIME)
+			return -ERESTARTNOHAND;
 		/*
 	 	 * Report back to the user the time still remaining.
 	 	 */
-		if (rmtp != NULL && !(flags & TIMER_ABSTIME) &&
-		    copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
+		if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
 			return -EFAULT;
 
 		restart_block->fn = posix_cpu_nsleep_restart;
-		/* Caller already set restart_block->arg1 */
 		restart_block->arg0 = which_clock;
 		restart_block->arg1 = (unsigned long) rmtp;
 		restart_block->arg2 = rqtp->tv_sec;
 		restart_block->arg3 = rqtp->tv_nsec;
-
-		error = -ERESTART_RESTARTBLOCK;
 	}
-
 	return error;
 }
 
@@ -1487,13 +1501,31 @@ long posix_cpu_nsleep_restart(struct restart_block *restart_block)
 	clockid_t which_clock = restart_block->arg0;
 	struct timespec __user *rmtp;
 	struct timespec t;
+	struct itimerspec it;
+	int error;
 
 	rmtp = (struct timespec __user *) restart_block->arg1;
 	t.tv_sec = restart_block->arg2;
 	t.tv_nsec = restart_block->arg3;
 
 	restart_block->fn = do_no_restart_syscall;
-	return posix_cpu_nsleep(which_clock, TIMER_ABSTIME, &t, rmtp);
+	error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
+
+	if (error == -ERESTART_RESTARTBLOCK) {
+		/*
+	 	 * Report back to the user the time still remaining.
+	 	 */
+		if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
+			return -EFAULT;
+
+		restart_block->fn = posix_cpu_nsleep_restart;
+		restart_block->arg0 = which_clock;
+		restart_block->arg1 = (unsigned long) rmtp;
+		restart_block->arg2 = t.tv_sec;
+		restart_block->arg3 = t.tv_nsec;
+	}
+	return error;
+
 }