Date:   Tue,  6 Aug 2019 14:10:47 -0700
From:   Nathan Huckleberry <nhuck@...gle.com>
To:     mark.rutland@....com
Cc:     clang-built-linux@...glegroups.com, linux-kernel@...r.kernel.org,
        Nathan Huckleberry <nhuck@...gle.com>
Subject: [RFC PATCH 2/2] Add clang-tidy irq-balancing annotations for arm64

This patch is not intended to be merged.  It simply shows the scale of
the effort involved in applying annotations in the case of intentionally
unbalanced calls to local_irq_disable.

Signed-off-by: Nathan Huckleberry <nhuck@...gle.com>
---
 arch/arm64/kernel/debug-monitors.c  | 1 +
 arch/arm64/kernel/machine_kexec.c   | 1 +
 arch/arm64/kernel/process.c         | 4 ++++
 arch/arm64/kernel/smp.c             | 1 +
 drivers/tty/sysrq.c                 | 1 +
 include/linux/compiler_attributes.h | 7 +++++++
 init/main.c                         | 1 +
 kernel/irq/handle.c                 | 1 +
 kernel/power/suspend.c              | 2 ++
 kernel/sched/core.c                 | 1 +
 kernel/sched/fair.c                 | 1 +
 kernel/sched/idle.c                 | 6 ++++++
 kernel/stop_machine.c               | 1 +
 mm/migrate.c                        | 1 +
 net/core/dev.c                      | 1 +
 15 files changed, 30 insertions(+)

diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index f8719bd30850..13552daeadd7 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -221,6 +221,7 @@ static int call_step_hook(struct pt_regs *regs, unsigned int esr)
 }
 NOKPROBE_SYMBOL(call_step_hook);
 
+__unbalanced_irq
 static void send_user_sigtrap(int si_code)
 {
 	struct pt_regs *regs = current_pt_regs();
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index 0df8493624e0..7880c3d336d5 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -258,6 +258,7 @@ static void machine_kexec_mask_interrupts(void)
 /**
  * machine_crash_shutdown - shutdown non-crashing cpus and save registers
  */
+__unbalanced_irq
 void machine_crash_shutdown(struct pt_regs *regs)
 {
 	local_irq_disable();
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 9856395ccdb7..30cec11dc82b 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -111,6 +111,7 @@ void cpu_do_idle(void)
 /*
  * This is our default idle handler.
  */
+__unbalanced_irq
 void arch_cpu_idle(void)
 {
 	/*
@@ -149,6 +150,7 @@ void machine_shutdown(void)
  * activity (executing tasks, handling interrupts). smp_send_stop()
  * achieves this.
  */
+__unbalanced_irq
 void machine_halt(void)
 {
 	local_irq_disable();
@@ -162,6 +164,7 @@ void machine_halt(void)
  * achieves this. When the system power is turned off, it will take all CPUs
  * with it.
  */
+__unbalanced_irq
 void machine_power_off(void)
 {
 	local_irq_disable();
@@ -179,6 +182,7 @@ void machine_power_off(void)
  * executing pre-reset code, and using RAM that the primary CPU's code wishes
  * to use. Implementing such co-ordination would be essentially impossible.
  */
+__unbalanced_irq
 void machine_restart(char *cmd)
 {
 	/* Disable interrupts first */
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 6dcf9607d770..78da6f7b5bcd 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -852,6 +852,7 @@ static void ipi_cpu_stop(unsigned int cpu)
 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
 #endif
 
+__unbalanced_irq
 static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
 {
 #ifdef CONFIG_KEXEC_CORE
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 573b2055173c..53bac6cb39c3 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -146,6 +146,7 @@ static struct sysrq_key_op sysrq_crash_op = {
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
+__unbalanced_irq
 static void sysrq_handle_reboot(int key)
 {
 	lockdep_off();
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index 6b318efd8a74..e2aaff9a2017 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -253,4 +253,11 @@
  */
 #define __weak                          __attribute__((__weak__))
 
+
+#if __has_attribute(__annotate__)
+# define __unbalanced_irq               __attribute__((annotate("ignore_irq_balancing")))
+#else
+# define __unbalanced_irq
+#endif
+
 #endif /* __LINUX_COMPILER_ATTRIBUTES_H */
diff --git a/init/main.c b/init/main.c
index 66a196c5e4c3..360a2714afe3 100644
--- a/init/main.c
+++ b/init/main.c
@@ -902,6 +902,7 @@ static inline void do_trace_initcall_finish(initcall_t fn, int ret)
 }
 #endif /* !TRACEPOINTS_ENABLED */
 
+__unbalanced_irq
 int __init_or_module do_one_initcall(initcall_t fn)
 {
 	int count = preempt_count();
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index a4ace611f47f..a74309c071b7 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -134,6 +134,7 @@ void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
 	wake_up_process(action->thread);
 }
 
+__unbalanced_irq
 irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags)
 {
 	irqreturn_t retval = IRQ_NONE;
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 096211299c07..41bc4b9b4f0e 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -380,12 +380,14 @@ static int suspend_prepare(suspend_state_t state)
 }
 
 /* default implementation */
+__unbalanced_irq
 void __weak arch_suspend_disable_irqs(void)
 {
 	local_irq_disable();
 }
 
 /* default implementation */
+__unbalanced_irq
 void __weak arch_suspend_enable_irqs(void)
 {
 	local_irq_enable();
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 874c427742a9..465d4ef60e1a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3366,6 +3366,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
  *
  * WARNING: must be called with preemption disabled!
  */
+__unbalanced_irq
 static void __sched notrace __schedule(bool preempt)
 {
 	struct task_struct *prev, *next;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f35930f5e528..9f147a2239ac 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9334,6 +9334,7 @@ update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
  * least 1 task to be running on each physical CPU where possible, and
  * avoids physical / logical imbalances.
  */
+__unbalanced_irq
 static int active_load_balance_cpu_stop(void *data)
 {
 	struct rq *busiest_rq = data;
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 80940939b733..b2174f71f1aa 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -52,6 +52,7 @@ static int __init cpu_idle_nopoll_setup(char *__unused)
 __setup("hlt", cpu_idle_nopoll_setup);
 #endif
 
+__unbalanced_irq
 static noinline int __cpuidle cpu_idle_poll(void)
 {
 	rcu_idle_enter();
@@ -74,6 +75,7 @@ void __weak arch_cpu_idle_prepare(void) { }
 void __weak arch_cpu_idle_enter(void) { }
 void __weak arch_cpu_idle_exit(void) { }
 void __weak arch_cpu_idle_dead(void) { }
+__unbalanced_irq
 void __weak arch_cpu_idle(void)
 {
 	cpu_idle_force_poll = 1;
@@ -85,6 +87,7 @@ void __weak arch_cpu_idle(void)
  *
  * To use when the cpuidle framework cannot be used.
  */
+__unbalanced_irq
 void __cpuidle default_idle_call(void)
 {
 	if (current_clr_polling_and_test()) {
@@ -96,6 +99,7 @@ void __cpuidle default_idle_call(void)
 	}
 }
 
+__unbalanced_irq
 static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 		      int next_state)
 {
@@ -126,6 +130,7 @@ static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
  * set, and it returns with polling set.  If it ever stops polling, it
  * must clear the polling bit.
  */
+__unbalanced_irq
 static void cpuidle_idle_call(void)
 {
 	struct cpuidle_device *dev = cpuidle_get_device();
@@ -222,6 +227,7 @@ static void cpuidle_idle_call(void)
  *
  * Called with polling cleared.
  */
+__unbalanced_irq
 static void do_idle(void)
 {
 	int cpu = smp_processor_id();
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 2b5a6754646f..1ff5f63b5f85 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -178,6 +178,7 @@ static void ack_state(struct multi_stop_data *msdata)
 }
 
 /* This is the cpu_stop function which stops the CPU. */
+__unbalanced_irq
 static int multi_cpu_stop(void *data)
 {
 	struct multi_stop_data *msdata = data;
diff --git a/mm/migrate.c b/mm/migrate.c
index f2ecc2855a12..bf2fd8e2c0f4 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -396,6 +396,7 @@ static int expected_page_refs(struct address_space *mapping, struct page *page)
  * 2 for pages with a mapping
  * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
  */
+__unbalanced_irq
 int migrate_page_move_mapping(struct address_space *mapping,
 		struct page *newpage, struct page *page, enum migrate_mode mode,
 		int extra_count)
diff --git a/net/core/dev.c b/net/core/dev.c
index d6edd218babd..04906dc6bd00 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5885,6 +5885,7 @@ static void net_rps_send_ipi(struct softnet_data *remsd)
  * net_rps_action_and_irq_enable sends any pending IPI's for rps.
  * Note: called with local irq disabled, but exits with local irq enabled.
  */
+__unbalanced_irq
 static void net_rps_action_and_irq_enable(struct softnet_data *sd)
 {
 #ifdef CONFIG_RPS
-- 
2.22.0.709.g102302147b-goog

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