uml: eliminate interrupts in the idle loop

Now, the idle loop now longer needs SIGALRM firing - it can just sleep for the
requisite amount of time and fake a timer interrupt when it finishes.

Any use of ITIMER_REAL now goes away.  disable_timer only turns off
ITIMER_VIRTUAL.  switch_timers is no longer needed, so it, and all calls, goes
away.

disable_timer now returns the amount of time remaining on the timer.
default_idle uses this to tell idle_sleep how long to sleep.  idle_sleep will
call alarm_handler if nanosleep returns 0, which is the case if it didn't
return early due to an interrupt.  Otherwise, it just returns.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 3 deletions

diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 53593c8b9c34..fbad174775ee 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -120,7 +120,6 @@ void (*handlers[_NSIG])(int sig, struct sigcontext *sc);
 void handle_signal(int sig, struct sigcontext *sc)
 {
 	unsigned long pending = 1UL << sig;
-	int timer = switch_timers(0);
 
 	do {
 		int nested, bail;
@@ -157,8 +156,6 @@ void handle_signal(int sig, struct sigcontext *sc)
 		if (!nested)
 			pending = from_irq_stack(nested);
 	} while (pending);
-
-	switch_timers(timer);
 }
 
 extern void hard_handler(int sig);