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lockdep: Use raw_cpu_*() for per-cpu variables

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Sven reported that commit a21ee6055c ("lockdep: Change
hardirq{s_enabled,_context} to per-cpu variables") caused trouble on
s390 because their this_cpu_*() primitives disable preemption which
then lands back tracing.

On the one hand, per-cpu ops should use preempt_*able_notrace() and
raw_local_irq_*(), on the other hand, we can trivialy use raw_cpu_*()
ops for this.

Fixes: a21ee6055c ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables")
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200821085348.192346882@infradead.org
This commit is contained in:
Peter Zijlstra 2020-08-20 09:13:30 +02:00
parent d012a7190f
commit fddf9055a6
3 changed files with 18 additions and 10 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

6
include/linux/irqflags.h
View file

@ -53,13 +53,13 @@ DECLARE_PER_CPU(int, hardirq_context);
extern void trace_hardirqs_off_finish(void);
extern void trace_hardirqs_on(void);
extern void trace_hardirqs_off(void);
# define lockdep_hardirq_context() (this_cpu_read(hardirq_context))
# define lockdep_hardirq_context() (raw_cpu_read(hardirq_context))
# define lockdep_softirq_context(p) ((p)->softirq_context)
# define lockdep_hardirqs_enabled() (this_cpu_read(hardirqs_enabled))
# define lockdep_softirqs_enabled(p) ((p)->softirqs_enabled)
# define lockdep_hardirq_enter() \
do { \
if (this_cpu_inc_return(hardirq_context) == 1) \
if (__this_cpu_inc_return(hardirq_context) == 1)\
current->hardirq_threaded = 0; \
} while (0)
# define lockdep_hardirq_threaded() \
@ -68,7 +68,7 @@ do { \
} while (0)
# define lockdep_hardirq_exit() \
do { \
this_cpu_dec(hardirq_context); \
__this_cpu_dec(hardirq_context); \
} while (0)
# define lockdep_softirq_enter() \
do { \

18
include/linux/lockdep.h
View file

@ -535,19 +535,27 @@ do { \
DECLARE_PER_CPU(int, hardirqs_enabled);
DECLARE_PER_CPU(int, hardirq_context);
/*
* The below lockdep_assert_*() macros use raw_cpu_read() to access the above
* per-cpu variables. This is required because this_cpu_read() will potentially
* call into preempt/irq-disable and that obviously isn't right. This is also
* correct because when IRQs are enabled, it doesn't matter if we accidentally
* read the value from our previous CPU.
*/
#define lockdep_assert_irqs_enabled() \
do { \
WARN_ON_ONCE(debug_locks && !this_cpu_read(hardirqs_enabled)); \
WARN_ON_ONCE(debug_locks && !raw_cpu_read(hardirqs_enabled)); \
} while (0)
#define lockdep_assert_irqs_disabled() \
do { \
WARN_ON_ONCE(debug_locks && this_cpu_read(hardirqs_enabled)); \
WARN_ON_ONCE(debug_locks && raw_cpu_read(hardirqs_enabled)); \
} while (0)
#define lockdep_assert_in_irq() \
do { \
WARN_ON_ONCE(debug_locks && !this_cpu_read(hardirq_context)); \
WARN_ON_ONCE(debug_locks && !raw_cpu_read(hardirq_context)); \
} while (0)
#define lockdep_assert_preemption_enabled() \
@ -555,7 +563,7 @@ do { \
WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \
debug_locks && \
(preempt_count() != 0 || \
!this_cpu_read(hardirqs_enabled))); \
!raw_cpu_read(hardirqs_enabled))); \
} while (0)
#define lockdep_assert_preemption_disabled() \
@ -563,7 +571,7 @@ do { \
WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \
debug_locks && \
(preempt_count() == 0 && \
this_cpu_read(hardirqs_enabled))); \
raw_cpu_read(hardirqs_enabled))); \
} while (0)
#else

4
kernel/locking/lockdep.c
View file

@ -3756,7 +3756,7 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
skip_checks:
/* we'll do an OFF -> ON transition: */
this_cpu_write(hardirqs_enabled, 1);
__this_cpu_write(hardirqs_enabled, 1);
trace->hardirq_enable_ip = ip;
trace->hardirq_enable_event = ++trace->irq_events;
debug_atomic_inc(hardirqs_on_events);
@ -3795,7 +3795,7 @@ void noinstr lockdep_hardirqs_off(unsigned long ip)
/*
* We have done an ON -> OFF transition:
*/
this_cpu_write(hardirqs_enabled, 0);
__this_cpu_write(hardirqs_enabled, 0);
trace->hardirq_disable_ip = ip;
trace->hardirq_disable_event = ++trace->irq_events;
debug_atomic_inc(hardirqs_off_events);