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 <j...@joelfernandes.org> 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