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lockdep: Add posixtimer context tracing bits

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Splitting run_posix_cpu_timers() into two parts is work in progress which
is stuck on other entry code related problems. The heavy lifting which
involves locking of sighand lock will be moved into task context so the
necessary execution time is burdened on the task and not on interrupt
context.

Until this work completes lockdep with the spinlock nesting rules enabled
would emit warnings for this known context.

Prevent it by setting "->irq_config = 1" for the invocation of
run_posix_cpu_timers() so lockdep does not complain when sighand lock is
acquried. This will be removed once the split is completed.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.751182723@linutronix.de
This commit is contained in:
Sebastian Andrzej Siewior 2020-03-21 12:26:04 +01:00 committed by Peter Zijlstra
parent 49915ac35c
commit d53f2b62fc
2 changed files with 17 additions and 1 deletions
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12
include/linux/irqflags.h
View File

@ -69,6 +69,16 @@ do { \
current->irq_config = 0; \
} while (0)
# define lockdep_posixtimer_enter() \
do { \
current->irq_config = 1; \
} while (0)
# define lockdep_posixtimer_exit() \
do { \
current->irq_config = 0; \
} while (0)
# define lockdep_irq_work_enter(__work) \
do { \
if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
@ -94,6 +104,8 @@ do { \
# define lockdep_softirq_exit() do { } while (0)
# define lockdep_hrtimer_enter(__hrtimer) do { } while (0)
# define lockdep_hrtimer_exit(__hrtimer) do { } while (0)
# define lockdep_posixtimer_enter() do { } while (0)
# define lockdep_posixtimer_exit() do { } while (0)
# define lockdep_irq_work_enter(__work) do { } while (0)
# define lockdep_irq_work_exit(__work) do { } while (0)
#endif

6
kernel/time/posix-cpu-timers.c
View File

@ -1126,8 +1126,11 @@ void run_posix_cpu_timers(void)
if (!fastpath_timer_check(tsk))
return;
if (!lock_task_sighand(tsk, &flags))
lockdep_posixtimer_enter();
if (!lock_task_sighand(tsk, &flags)) {
lockdep_posixtimer_exit();
return;
}
/*
* Here we take off tsk->signal->cpu_timers[N] and
* tsk->cpu_timers[N] all the timers that are firing, and
@ -1169,6 +1172,7 @@ void run_posix_cpu_timers(void)
cpu_timer_fire(timer);
spin_unlock(&timer->it_lock);
}
lockdep_posixtimer_exit();
}
/*