Commit 7a10e2a9 authored Nov 06, 2017 by Frederic Weisbecker Committed by Ingo Molnar Nov 08, 2017

x86: Use lockdep to assert IRQs are disabled/enabled



Use lockdep to check that IRQs are enabled or disabled as expected. This
way the sanity check only shows overhead when concurrency correctness
debug code is enabled.

It also makes no more sense to fix the IRQ flags when a bug is detected
as the assertion is now pure config-dependent debugging. And to quote
Peter Zijlstra:

	The whole if !disabled, disable logic is uber paranoid programming,
	but I don't think we've ever seen that WARN trigger, and if it does
	(and then burns the kernel) we at least know what happend.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David S . Miller <davem@davemloft.net>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1509980490-4285-8-git-send-email-frederic@kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 83efcbd0

arch/x86/entry/common.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -186,9 +186,7 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)

		addr_limit_user_check();

		if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled()))
		local_irq_disable();

		lockdep_assert_irqs_disabled();
		lockdep_sys_exit();

		cached_flags = READ_ONCE(ti->flags);

arch/x86/kernel/smpboot.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1095,7 +1095,7 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
		unsigned long flags;
		int err, ret = 0;

		WARN_ON(irqs_disabled());
		lockdep_assert_irqs_enabled();

		pr_debug("++++++++++++++++++++=_---CPU UP %u\n", cpu);

Admin message