sched/wait, arch/mips: Fix and convert wait_on_atomic_t() usage to the new wait_var_event() API

The old wait_on_atomic_t() is going to get removed, use the more
flexible wait_var_event() API instead.

And while there, fix a bug and add the missing wakeup...
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/mips/kernel/process.c

@@ -781,6 +781,8 @@ int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 	atomic_set(&task->mm->context.fp_mode_switching, 0);
 	preempt_enable();
 
+	wake_up_var(&task->mm->context.fp_mode_switching);
+
 	return 0;
 }
 

arch/mips/kernel/traps.c

@@ -1248,8 +1248,8 @@ static int enable_restore_fp_context(int msa)
 	 * If an FP mode switch is currently underway, wait for it to
 	 * complete before proceeding.
 	 */
-	wait_on_atomic_t(&current->mm->context.fp_mode_switching,
-			 atomic_t_wait, TASK_KILLABLE);
+	wait_var_event(&current->mm->context.fp_mode_switching,
+		       !atomic_read(&current->mm->context.fp_mode_switching));
 
 	if (!used_math()) {
 		/* First time FP context user. */