1 files changed, 39 insertions, 17 deletions

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 53cc09ceb0b..b2498835345 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -29,7 +29,6 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/irq.h>
 
-#include <asm/irq.h>
 /*
    - No shared variables, all the data are CPU local.
    - If a softirq needs serialization, let it serialize itself
@@ -100,13 +99,13 @@ static void __local_bh_disable(unsigned long ip, unsigned int cnt)
 
 	raw_local_irq_save(flags);
 	/*
-	 * The preempt tracer hooks into add_preempt_count and will break
+	 * The preempt tracer hooks into preempt_count_add and will break
 	 * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET
 	 * is set and before current->softirq_enabled is cleared.
 	 * We must manually increment preempt_count here and manually
 	 * call the trace_preempt_off later.
 	 */
-	preempt_count() += cnt;
+	__preempt_count_add(cnt);
 	/*
 	 * Were softirqs turned off above:
 	 */
@@ -120,7 +119,7 @@ static void __local_bh_disable(unsigned long ip, unsigned int cnt)
 #else /* !CONFIG_TRACE_IRQFLAGS */
 static inline void __local_bh_disable(unsigned long ip, unsigned int cnt)
 {
-	add_preempt_count(cnt);
+	preempt_count_add(cnt);
 	barrier();
 }
 #endif /* CONFIG_TRACE_IRQFLAGS */
@@ -134,12 +133,11 @@ EXPORT_SYMBOL(local_bh_disable);
 
 static void __local_bh_enable(unsigned int cnt)
 {
-	WARN_ON_ONCE(in_irq());
 	WARN_ON_ONCE(!irqs_disabled());
 
 	if (softirq_count() == cnt)
 		trace_softirqs_on(_RET_IP_);
-	sub_preempt_count(cnt);
+	preempt_count_sub(cnt);
 }
 
 /*
@@ -149,6 +147,7 @@ static void __local_bh_enable(unsigned int cnt)
  */
 void _local_bh_enable(void)
 {
+	WARN_ON_ONCE(in_irq());
 	__local_bh_enable(SOFTIRQ_DISABLE_OFFSET);
 }
 
@@ -169,12 +168,17 @@ static inline void _local_bh_enable_ip(unsigned long ip)
 	 * Keep preemption disabled until we are done with
 	 * softirq processing:
  	 */
-	sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1);
+	preempt_count_sub(SOFTIRQ_DISABLE_OFFSET - 1);
 
-	if (unlikely(!in_interrupt() && local_softirq_pending()))
+	if (unlikely(!in_interrupt() && local_softirq_pending())) {
+		/*
+		 * Run softirq if any pending. And do it in its own stack
+		 * as we may be calling this deep in a task call stack already.
+		 */
 		do_softirq();
+	}
 
-	dec_preempt_count();
+	preempt_count_dec();
 #ifdef CONFIG_TRACE_IRQFLAGS
 	local_irq_enable();
 #endif
@@ -256,7 +260,7 @@ restart:
 				       " exited with %08x?\n", vec_nr,
 				       softirq_to_name[vec_nr], h->action,
 				       prev_count, preempt_count());
-				preempt_count() = prev_count;
+				preempt_count_set(prev_count);
 			}
 
 			rcu_bh_qs(cpu);
@@ -280,10 +284,11 @@ restart:
 
 	account_irq_exit_time(current);
 	__local_bh_enable(SOFTIRQ_OFFSET);
+	WARN_ON_ONCE(in_interrupt());
 	tsk_restore_flags(current, old_flags, PF_MEMALLOC);
 }
 
-#ifndef __ARCH_HAS_DO_SOFTIRQ
+
 
 asmlinkage void do_softirq(void)
 {
@@ -298,13 +303,11 @@ asmlinkage void do_softirq(void)
 	pending = local_softirq_pending();
 
 	if (pending)
-		__do_softirq();
+		do_softirq_own_stack();
 
 	local_irq_restore(flags);
 }
 
-#endif
-
 /*
  * Enter an interrupt context.
  */
@@ -328,10 +331,25 @@ void irq_enter(void)
 
 static inline void invoke_softirq(void)
 {
-	if (!force_irqthreads)
+	if (!force_irqthreads) {
+#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
+		/*
+		 * We can safely execute softirq on the current stack if
+		 * it is the irq stack, because it should be near empty
+		 * at this stage.
+		 */
 		__do_softirq();
-	else
+#else
+		/*
+		 * Otherwise, irq_exit() is called on the task stack that can
+		 * be potentially deep already. So call softirq in its own stack
+		 * to prevent from any overrun.
+		 */
+		do_softirq_own_stack();
+#endif
+	} else {
 		wakeup_softirqd();
+	}
 }
 
 static inline void tick_irq_exit(void)
@@ -360,7 +378,7 @@ void irq_exit(void)
 
 	account_irq_exit_time(current);
 	trace_hardirq_exit();
-	sub_preempt_count(HARDIRQ_OFFSET);
+	preempt_count_sub(HARDIRQ_OFFSET);
 	if (!in_interrupt() && local_softirq_pending())
 		invoke_softirq();
 
@@ -762,6 +780,10 @@ static void run_ksoftirqd(unsigned int cpu)
 {
 	local_irq_disable();
 	if (local_softirq_pending()) {
+		/*
+		 * We can safely run softirq on inline stack, as we are not deep
+		 * in the task stack here.
+		 */
 		__do_softirq();
 		rcu_note_context_switch(cpu);
 		local_irq_enable();