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tracing: Provide lockdep less trace_hardirqs_on/off() variants

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trace_hardirqs_on/off() is only partially safe vs. RCU idle. The tracer
core itself is safe, but the resulting tracepoints can be utilized by
e.g. BPF which is unsafe.

Provide variants which do not contain the lockdep invocation so the lockdep
and tracer invocations can be split at the call site and placed
properly. This is required because lockdep needs to be aware of the state
before switching away from RCU idle and after switching to RCU idle because
these transitions can take locks.

As these code pathes are going to be non-instrumentable the tracer can be
invoked after RCU is turned on and before the switch to RCU idle. So for
these new variants there is no need to invoke the rcuidle aware tracer
functions.

Name them so they match the lockdep counterparts.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134100.270771162@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-03-04 13:09:50 +01:00
parent 6553896666
commit 0995a5dfbe
2 changed files with 41 additions and 0 deletions
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4
include/linux/irqflags.h
View file

@ -29,6 +29,8 @@
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
extern void trace_hardirqs_on_prepare(void);
extern void trace_hardirqs_off_prepare(void);
extern void trace_hardirqs_on(void);
extern void trace_hardirqs_off(void);
# define lockdep_hardirq_context(p) ((p)->hardirq_context)
@ -96,6 +98,8 @@ do { \
} while (0)
#else
# define trace_hardirqs_on_prepare() do { } while (0)
# define trace_hardirqs_off_prepare() do { } while (0)
# define trace_hardirqs_on() do { } while (0)
# define trace_hardirqs_off() do { } while (0)
# define lockdep_hardirq_context(p) 0