4 files changed, 26 insertions, 21 deletions

diff --git a/arch/um/include/os.h b/arch/um/include/os.h
index e861c8adb44f..12de1ea68370 100644
--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -250,7 +250,7 @@ extern void os_dump_core(void);
 /* time.c */
 #define BILLION (1000 * 1000 * 1000)
 
-extern void switch_timers(int to_real);
+extern int switch_timers(int to_real);
 extern void idle_sleep(int secs);
 extern int set_interval(int is_virtual);
 extern void disable_timer(void);
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 8a6882dfba01..56d75afedbf7 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -95,18 +95,11 @@ void *_switch_to(void *prev, void *next, void *last)
         do {
                 current->thread.saved_task = NULL;
 
-                /* XXX need to check runqueues[cpu].idle */
-                if (current->pid == 0)
-                        switch_timers(0);
-
                 switch_threads(&from->thread.switch_buf,
                                &to->thread.switch_buf);
 
                 arch_switch_to(current->thread.prev_sched, current);
 
-                if (current->pid == 0)
-                        switch_timers(1);
-
                 if (current->thread.saved_task)
                         show_regs(&(current->thread.regs));
                 next= current->thread.saved_task;
@@ -251,7 +244,9 @@ void default_idle(void)
                 if (need_resched())
                         schedule();
 
+                switch_timers(1);
                 idle_sleep(10);
+                switch_timers(0);
         }
 }
 
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 49c113b576b7..1c5267ec13b0 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -59,17 +59,11 @@ static void real_alarm_handler(int sig, struct sigcontext *sc)
 {
         struct uml_pt_regs regs;
 
-        if (sig == SIGALRM)
-                switch_timers(0);
-
         if (sc != NULL)
                 copy_sc(&regs, sc);
         regs.is_user = 0;
         unblock_signals();
         timer_handler(sig, &regs);
-
-        if (sig == SIGALRM)
-                switch_timers(1);
 }
 
 void alarm_handler(int sig, struct sigcontext *sc)
@@ -116,6 +110,7 @@ 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;
@@ -152,6 +147,8 @@ 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);
diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
index 5939653f99ea..a16a0f484edc 100644
--- a/arch/um/os-Linux/time.c
+++ b/arch/um/os-Linux/time.c
@@ -12,6 +12,8 @@
 #include "os.h"
 #include "user.h"
 
+static int is_real_timer = 0;
+
 int set_interval(int is_virtual)
 {
         int usec = 1000000/UM_HZ;
@@ -39,12 +41,14 @@ void disable_timer(void)
         signal(SIGVTALRM, SIG_IGN);
 }
 
-void switch_timers(int to_real)
+int switch_timers(int to_real)
 {
         struct itimerval disable = ((struct itimerval) { { 0, 0 }, { 0, 0 }});
-        struct itimerval enable = ((struct itimerval) { { 0, 1000000/UM_HZ },
-                                                        { 0, 1000000/UM_HZ }});
-        int old, new;
+        struct itimerval enable;
+        int old, new, old_type = is_real_timer;
+
+        if(to_real == old_type)
+                return to_real;
 
         if (to_real) {
                 old = ITIMER_VIRTUAL;
@@ -55,10 +59,19 @@ void switch_timers(int to_real)
                 new = ITIMER_VIRTUAL;
         }
 
-        if ((setitimer(old, &disable, NULL) < 0) ||
-            (setitimer(new, &enable, NULL)))
-                printk(UM_KERN_ERR "switch_timers - setitimer failed, "
+        if (setitimer(old, &disable, &enable) < 0)
+                printk(UM_KERN_ERR "switch_timers - setitimer disable failed, "
+                       "errno = %d\n", errno);
+
+        if((enable.it_value.tv_sec == 0) && (enable.it_value.tv_usec == 0))
+                enable.it_value = enable.it_interval;
+
+        if (setitimer(new, &enable, NULL))
+                printk(UM_KERN_ERR "switch_timers - setitimer enable failed, "
                        "errno = %d\n", errno);
+
+        is_real_timer = to_real;
+        return old_type;
 }
 
 unsigned long long os_nsecs(void)