mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-29 23:53:32 +00:00
044d0d6de9
Problem:
raw_local_irq_save(); // software state on
local_irq_save(); // software state off
...
local_irq_restore(); // software state still off, because we don't enable IRQs
raw_local_irq_restore(); // software state still off, *whoopsie*
existing instances:
- lock_acquire()
raw_local_irq_save()
__lock_acquire()
arch_spin_lock(&graph_lock)
pv_wait() := kvm_wait() (same or worse for Xen/HyperV)
local_irq_save()
- trace_clock_global()
raw_local_irq_save()
arch_spin_lock()
pv_wait() := kvm_wait()
local_irq_save()
- apic_retrigger_irq()
raw_local_irq_save()
apic->send_IPI() := default_send_IPI_single_phys()
local_irq_save()
Possible solutions:
A) make it work by enabling the tracing inside raw_*()
B) make it work by keeping tracing disabled inside raw_*()
C) call it broken and clean it up now
Now, given that the only reason to use the raw_* variant is because you don't
want tracing. Therefore A) seems like a weird option (although it can be done).
C) is tempting, but OTOH it ends up converting a _lot_ of code to raw just
because there is one raw user, this strips the validation/tracing off for all
the other users.
So we pick B) and declare any code that ends up doing:
raw_local_irq_save()
local_irq_save()
lockdep_assert_irqs_disabled();
broken. AFAICT this problem has existed forever, the only reason it came
up is because commit: 859d069ee1 ("lockdep: Prepare for NMI IRQ
state tracking") changed IRQ tracing vs lockdep recursion and the
first instance is fairly common, the other cases hardly ever happen.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[rewrote changelog]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Marco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/20200723105615.1268126-1-npiggin@gmail.com
251 lines
7.4 KiB
C
251 lines
7.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/linux/irqflags.h
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*
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* IRQ flags tracing: follow the state of the hardirq and softirq flags and
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* provide callbacks for transitions between ON and OFF states.
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*
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* This file gets included from lowlevel asm headers too, to provide
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* wrapped versions of the local_irq_*() APIs, based on the
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* raw_local_irq_*() macros from the lowlevel headers.
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*/
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#ifndef _LINUX_TRACE_IRQFLAGS_H
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#define _LINUX_TRACE_IRQFLAGS_H
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#include <linux/typecheck.h>
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#include <asm/irqflags.h>
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#include <asm/percpu.h>
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/* Currently lockdep_softirqs_on/off is used only by lockdep */
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#ifdef CONFIG_PROVE_LOCKING
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extern void lockdep_softirqs_on(unsigned long ip);
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extern void lockdep_softirqs_off(unsigned long ip);
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extern void lockdep_hardirqs_on_prepare(unsigned long ip);
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extern void lockdep_hardirqs_on(unsigned long ip);
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extern void lockdep_hardirqs_off(unsigned long ip);
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#else
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static inline void lockdep_softirqs_on(unsigned long ip) { }
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static inline void lockdep_softirqs_off(unsigned long ip) { }
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static inline void lockdep_hardirqs_on_prepare(unsigned long ip) { }
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static inline void lockdep_hardirqs_on(unsigned long ip) { }
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static inline void lockdep_hardirqs_off(unsigned long ip) { }
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#endif
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#ifdef CONFIG_TRACE_IRQFLAGS
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/* Per-task IRQ trace events information. */
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struct irqtrace_events {
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unsigned int irq_events;
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unsigned long hardirq_enable_ip;
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unsigned long hardirq_disable_ip;
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unsigned int hardirq_enable_event;
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unsigned int hardirq_disable_event;
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unsigned long softirq_disable_ip;
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unsigned long softirq_enable_ip;
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unsigned int softirq_disable_event;
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unsigned int softirq_enable_event;
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};
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DECLARE_PER_CPU(int, hardirqs_enabled);
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DECLARE_PER_CPU(int, hardirq_context);
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extern void trace_hardirqs_on_prepare(void);
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extern void trace_hardirqs_off_finish(void);
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extern void trace_hardirqs_on(void);
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extern void trace_hardirqs_off(void);
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# define lockdep_hardirq_context() (raw_cpu_read(hardirq_context))
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# define lockdep_softirq_context(p) ((p)->softirq_context)
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# define lockdep_hardirqs_enabled() (this_cpu_read(hardirqs_enabled))
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# define lockdep_softirqs_enabled(p) ((p)->softirqs_enabled)
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# define lockdep_hardirq_enter() \
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do { \
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if (__this_cpu_inc_return(hardirq_context) == 1)\
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current->hardirq_threaded = 0; \
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} while (0)
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# define lockdep_hardirq_threaded() \
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do { \
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current->hardirq_threaded = 1; \
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} while (0)
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# define lockdep_hardirq_exit() \
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do { \
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__this_cpu_dec(hardirq_context); \
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} while (0)
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# define lockdep_softirq_enter() \
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do { \
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current->softirq_context++; \
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} while (0)
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# define lockdep_softirq_exit() \
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do { \
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current->softirq_context--; \
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} while (0)
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# define lockdep_hrtimer_enter(__hrtimer) \
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({ \
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bool __expires_hardirq = true; \
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\
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if (!__hrtimer->is_hard) { \
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current->irq_config = 1; \
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__expires_hardirq = false; \
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} \
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__expires_hardirq; \
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})
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# define lockdep_hrtimer_exit(__expires_hardirq) \
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do { \
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if (!__expires_hardirq) \
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current->irq_config = 0; \
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} while (0)
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# define lockdep_posixtimer_enter() \
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do { \
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current->irq_config = 1; \
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} while (0)
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# define lockdep_posixtimer_exit() \
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do { \
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current->irq_config = 0; \
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} while (0)
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# define lockdep_irq_work_enter(__work) \
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do { \
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if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
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current->irq_config = 1; \
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} while (0)
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# define lockdep_irq_work_exit(__work) \
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do { \
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if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
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current->irq_config = 0; \
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} while (0)
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#else
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# define trace_hardirqs_on_prepare() do { } while (0)
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# define trace_hardirqs_off_finish() do { } while (0)
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# define trace_hardirqs_on() do { } while (0)
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# define trace_hardirqs_off() do { } while (0)
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# define lockdep_hardirq_context() 0
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# define lockdep_softirq_context(p) 0
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# define lockdep_hardirqs_enabled() 0
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# define lockdep_softirqs_enabled(p) 0
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# define lockdep_hardirq_enter() do { } while (0)
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# define lockdep_hardirq_threaded() do { } while (0)
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# define lockdep_hardirq_exit() do { } while (0)
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# define lockdep_softirq_enter() do { } while (0)
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# define lockdep_softirq_exit() do { } while (0)
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# define lockdep_hrtimer_enter(__hrtimer) false
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# define lockdep_hrtimer_exit(__context) do { } while (0)
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# define lockdep_posixtimer_enter() do { } while (0)
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# define lockdep_posixtimer_exit() do { } while (0)
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# define lockdep_irq_work_enter(__work) do { } while (0)
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# define lockdep_irq_work_exit(__work) do { } while (0)
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#endif
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#if defined(CONFIG_IRQSOFF_TRACER) || \
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defined(CONFIG_PREEMPT_TRACER)
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extern void stop_critical_timings(void);
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extern void start_critical_timings(void);
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#else
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# define stop_critical_timings() do { } while (0)
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# define start_critical_timings() do { } while (0)
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#endif
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/*
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* Wrap the arch provided IRQ routines to provide appropriate checks.
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*/
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#define raw_local_irq_disable() arch_local_irq_disable()
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#define raw_local_irq_enable() arch_local_irq_enable()
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#define raw_local_irq_save(flags) \
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do { \
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typecheck(unsigned long, flags); \
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flags = arch_local_irq_save(); \
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} while (0)
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#define raw_local_irq_restore(flags) \
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do { \
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typecheck(unsigned long, flags); \
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arch_local_irq_restore(flags); \
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} while (0)
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#define raw_local_save_flags(flags) \
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do { \
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typecheck(unsigned long, flags); \
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flags = arch_local_save_flags(); \
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} while (0)
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#define raw_irqs_disabled_flags(flags) \
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({ \
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typecheck(unsigned long, flags); \
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arch_irqs_disabled_flags(flags); \
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})
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#define raw_irqs_disabled() (arch_irqs_disabled())
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#define raw_safe_halt() arch_safe_halt()
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/*
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* The local_irq_*() APIs are equal to the raw_local_irq*()
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* if !TRACE_IRQFLAGS.
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*/
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#ifdef CONFIG_TRACE_IRQFLAGS
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#define local_irq_enable() \
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do { \
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trace_hardirqs_on(); \
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raw_local_irq_enable(); \
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} while (0)
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#define local_irq_disable() \
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do { \
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bool was_disabled = raw_irqs_disabled();\
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raw_local_irq_disable(); \
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if (!was_disabled) \
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trace_hardirqs_off(); \
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} while (0)
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#define local_irq_save(flags) \
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do { \
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raw_local_irq_save(flags); \
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if (!raw_irqs_disabled_flags(flags)) \
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trace_hardirqs_off(); \
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} while (0)
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#define local_irq_restore(flags) \
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do { \
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if (!raw_irqs_disabled_flags(flags)) \
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trace_hardirqs_on(); \
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raw_local_irq_restore(flags); \
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} while (0)
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#define safe_halt() \
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do { \
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trace_hardirqs_on(); \
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raw_safe_halt(); \
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} while (0)
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#else /* !CONFIG_TRACE_IRQFLAGS */
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#define local_irq_enable() do { raw_local_irq_enable(); } while (0)
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#define local_irq_disable() do { raw_local_irq_disable(); } while (0)
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#define local_irq_save(flags) do { raw_local_irq_save(flags); } while (0)
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#define local_irq_restore(flags) do { raw_local_irq_restore(flags); } while (0)
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#define safe_halt() do { raw_safe_halt(); } while (0)
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#endif /* CONFIG_TRACE_IRQFLAGS */
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#define local_save_flags(flags) raw_local_save_flags(flags)
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/*
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* Some architectures don't define arch_irqs_disabled(), so even if either
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* definition would be fine we need to use different ones for the time being
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* to avoid build issues.
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*/
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#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
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#define irqs_disabled() \
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({ \
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unsigned long _flags; \
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raw_local_save_flags(_flags); \
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raw_irqs_disabled_flags(_flags); \
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})
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#else /* !CONFIG_TRACE_IRQFLAGS_SUPPORT */
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#define irqs_disabled() raw_irqs_disabled()
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#endif /* CONFIG_TRACE_IRQFLAGS_SUPPORT */
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#define irqs_disabled_flags(flags) raw_irqs_disabled_flags(flags)
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#endif
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