Re: [PATCH tip/core/rcu 06/19] rcu: Add warning to detect half-interrupts

[Steven Rostedt]

On Wed, 13 Mar 2019 11:09:48 -0400
Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote:

> AFAICS, lockdep does not specifically track when we enter an interrupt, but
> rather only tracks when interrupts are enabled/disabled.

It does:

#define __irq_enter()					\
	do {						\
		account_irq_enter_time(current);	\
		preempt_count_add(HARDIRQ_OFFSET);	\
		trace_hardirq_enter();			\
	} while (0)

# define trace_hardirq_enter()			\
do {						\
	current->hardirq_context++;		\
} while (0)


And if the hardirq_context ever does not match "in_irq()" lockdep will
complain loudly.

-- Steve