From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 29 May 2020 21:27:39 +0000 (+0200)
Subject: x86/entry: Clarify irq_{enter,exit}_rcu()
X-Git-Tag: Ubuntu-5.13.0-19.19~5754^2~16
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=59bc300b712998d10254ee20e24f2e7ec09c560a;p=mirror_ubuntu-jammy-kernel.git

x86/entry: Clarify irq_{enter,exit}_rcu()

Because:

  irq_enter_rcu() includes lockdep_hardirq_enter()
  irq_exit_rcu() does *NOT* include lockdep_hardirq_exit()

Which resulted in two 'stray' lockdep_hardirq_exit() calls in
idtentry.h, and me spending a long time trying to find the matching
enter calls.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.359433429@infradead.org
---

diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 38b672ded40b..d203c541a65a 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -206,7 +206,6 @@ __visible noinstr void func(struct pt_regs *regs,			\
 	kvm_set_cpu_l1tf_flush_l1d();					\
 	__##func (regs, (u8)error_code);				\
 	irq_exit_rcu();							\
-	lockdep_hardirq_exit();						\
 	instrumentation_end();						\
 	idtentry_exit_cond_rcu(regs, rcu_exit);				\
 }									\
@@ -249,7 +248,6 @@ __visible noinstr void func(struct pt_regs *regs)			\
 	kvm_set_cpu_l1tf_flush_l1d();					\
 	run_on_irqstack_cond(__##func, regs, regs);			\
 	irq_exit_rcu();							\
-	lockdep_hardirq_exit();						\
 	instrumentation_end();						\
 	idtentry_exit_cond_rcu(regs, rcu_exit);				\
 }									\
diff --git a/kernel/softirq.c b/kernel/softirq.c
index beb8e3a66c7c..c4201b7f42b1 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -404,12 +404,7 @@ static inline void tick_irq_exit(void)
 #endif
 }
 
-/**
- * irq_exit_rcu() - Exit an interrupt context without updating RCU
- *
- * Also processes softirqs if needed and possible.
- */
-void irq_exit_rcu(void)
+static inline void __irq_exit_rcu(void)
 {
 #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
 	local_irq_disable();
@@ -424,6 +419,18 @@ void irq_exit_rcu(void)
 	tick_irq_exit();
 }
 
+/**
+ * irq_exit_rcu() - Exit an interrupt context without updating RCU
+ *
+ * Also processes softirqs if needed and possible.
+ */
+void irq_exit_rcu(void)
+{
+	__irq_exit_rcu();
+	 /* must be last! */
+	lockdep_hardirq_exit();
+}
+
 /**
  * irq_exit - Exit an interrupt context, update RCU and lockdep
  *
@@ -431,7 +438,7 @@ void irq_exit_rcu(void)
  */
 void irq_exit(void)
 {
-	irq_exit_rcu();
+	__irq_exit_rcu();
 	rcu_irq_exit();
 	 /* must be last! */
 	lockdep_hardirq_exit();