Upgrade to 4.4.50-rt62

[kvmfornfv.git] / kernel / arch / x86 / kernel / traps.c

diff --git a/kernel/arch/x86/kernel/traps.c b/kernel/arch/x86/kernel/traps.c
index ade185a..679302c 100644 (file)
--- a/kernel/arch/x86/kernel/traps.c
+++ b/kernel/arch/x86/kernel/traps.c
@@ -109,6 +109,12 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
        preempt_count_dec();
 }
 
+/*
+ * In IST context, we explicitly disable preemption.  This serves two
+ * purposes: it makes it much less likely that we would accidentally
+ * schedule in IST context and it will force a warning if we somehow
+ * manage to schedule by accident.
+ */
 void ist_enter(struct pt_regs *regs)
 {
        if (user_mode(regs)) {
@@ -123,13 +129,7 @@ void ist_enter(struct pt_regs *regs)
                rcu_nmi_enter();
        }
 
-       /*
-        * We are atomic because we're on the IST stack; or we're on
-        * x86_32, in which case we still shouldn't schedule; or we're
-        * on x86_64 and entered from user mode, in which case we're
-        * still atomic unless ist_begin_non_atomic is called.
-        */
-       preempt_count_add(HARDIRQ_OFFSET);
+       preempt_disable();
 
        /* This code is a bit fragile.  Test it. */
        RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
@@ -137,7 +137,7 @@ void ist_enter(struct pt_regs *regs)
 
 void ist_exit(struct pt_regs *regs)
 {
-       preempt_count_sub(HARDIRQ_OFFSET);
+       preempt_enable_no_resched();
 
        if (!user_mode(regs))
                rcu_nmi_exit();
@@ -168,7 +168,7 @@ void ist_begin_non_atomic(struct pt_regs *regs)
        BUG_ON((unsigned long)(current_top_of_stack() -
                               current_stack_pointer()) >= THREAD_SIZE);
 
-       preempt_count_sub(HARDIRQ_OFFSET);
+       preempt_enable_no_resched();
 }
 
 /**
@@ -178,7 +178,7 @@ void ist_begin_non_atomic(struct pt_regs *regs)
  */
 void ist_end_non_atomic(void)
 {
-       preempt_count_add(HARDIRQ_OFFSET);
+       preempt_disable();
 }
 
 static nokprobe_inline int