sh: fix xtime_lock deadlocking.

move update_process_times() out from under xtime_lock.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

2 files changed, 32 insertions, 18 deletions

diff --git a/arch/sh/kernel/time_32.c b/arch/sh/kernel/time_32.c
index 2bc04bfee738..7281342c044d 100644
--- a/arch/sh/kernel/time_32.c
+++ b/arch/sh/kernel/time_32.c
@@ -120,10 +120,6 @@ static long last_rtc_update;
  */
 void handle_timer_tick(void)
 {
-	do_timer(1);
-#ifndef CONFIG_SMP
-	update_process_times(user_mode(get_irq_regs()));
-#endif
 	if (current->pid)
 		profile_tick(CPU_PROFILING);
 
@@ -133,6 +129,16 @@ void handle_timer_tick(void)
 #endif
 
 	/*
+	 * Here we are in the timer irq handler. We just have irqs locally
+	 * disabled but we don't know if the timer_bh is running on the other
+	 * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
+	 * the irq version of write_lock because as just said we have irq
+	 * locally disabled. -arca
+	 */
+	write_seqlock(&xtime_lock);
+	do_timer(1);
+
+	/*
 	 * If we have an externally synchronized Linux clock, then update
 	 * RTC clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 	 * called as close as possible to 500 ms before the new second starts.
@@ -147,6 +153,11 @@ void handle_timer_tick(void)
 			/* do it again in 60s */
 			last_rtc_update = xtime.tv_sec - 600;
 	}
+	write_sequnlock(&xtime_lock);
+
+#ifndef CONFIG_SMP
+	update_process_times(user_mode(get_irq_regs()));
+#endif
 }
 #endif /* !CONFIG_GENERIC_CLOCKEVENTS */
 
diff --git a/arch/sh/kernel/time_64.c b/arch/sh/kernel/time_64.c
index f819ba38a6ce..898977ee2030 100644
--- a/arch/sh/kernel/time_64.c
+++ b/arch/sh/kernel/time_64.c
@@ -229,15 +229,22 @@ static long last_rtc_update;
 static inline void do_timer_interrupt(void)
 {
 	unsigned long long current_ctc;
+
+	if (current->pid)
+		profile_tick(CPU_PROFILING);
+
+	/*
+	 * Here we are in the timer irq handler. We just have irqs locally
+	 * disabled but we don't know if the timer_bh is running on the other
+	 * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
+	 * the irq version of write_lock because as just said we have irq
+	 * locally disabled. -arca
+	 */
+	write_lock(&xtime_lock);
 	asm ("getcon cr62, %0" : "=r" (current_ctc));
 	ctc_last_interrupt = (unsigned long) current_ctc;
 
 	do_timer(1);
-#ifndef CONFIG_SMP
-	update_process_times(user_mode(get_irq_regs()));
-#endif
-	if (current->pid)
-		profile_tick(CPU_PROFILING);
 
 #ifdef CONFIG_HEARTBEAT
 	if (sh_mv.mv_heartbeat != NULL)
@@ -259,6 +266,11 @@ static inline void do_timer_interrupt(void)
 			/* do it again in 60 s */
 			last_rtc_update = xtime.tv_sec - 600;
 	}
+	write_unlock(&xtime_lock);
+
+#ifndef CONFIG_SMP
+	update_process_times(user_mode(get_irq_regs()));
+#endif
 }
 
 /*
@@ -275,16 +287,7 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id)
 	timer_status &= ~0x100;
 	ctrl_outw(timer_status, TMU0_TCR);
 
-	/*
-	 * Here we are in the timer irq handler. We just have irqs locally
-	 * disabled but we don't know if the timer_bh is running on the other
-	 * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
-	 * the irq version of write_lock because as just said we have irq
-	 * locally disabled. -arca
-	 */
-	write_lock(&xtime_lock);
 	do_timer_interrupt();
-	write_unlock(&xtime_lock);
 
 	return IRQ_HANDLED;
 }