Messages in this thread | | | Date | Fri, 27 Jul 2018 12:26:59 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH v11 2/3] tracepoint: Make rcuidle tracepoint callers use SRCU |
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On Thu, 26 Jul 2018 16:50:43 -0700 Joel Fernandes <joel@joelfernandes.org> wrote:
> F > include/linux/tracepoint.h | 41 ++++++++++++++++++++++++++++++-------- > kernel/tracepoint.c | 16 ++++++++++++++- > 2 files changed, 48 insertions(+), 9 deletions(-) > > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > index 19a690b559ca..6e7bc6ebfcd8 100644 > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -15,6 +15,7 @@ > */ > > #include <linux/smp.h> > +#include <linux/srcu.h> > #include <linux/errno.h> > #include <linux/types.h> > #include <linux/cpumask.h> > @@ -33,6 +34,8 @@ struct trace_eval_map { > > #define TRACEPOINT_DEFAULT_PRIO 10 > > +extern struct srcu_struct tracepoint_srcu; > + > extern int > tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data); > extern int > @@ -75,10 +78,16 @@ int unregister_tracepoint_module_notifier(struct notifier_block *nb) > * probe unregistration and the end of module exit to make sure there is no > * caller executing a probe when it is freed. > */ > +#ifdef CONFIG_TRACEPOINTS > static inline void tracepoint_synchronize_unregister(void) > { > + synchronize_srcu(&tracepoint_srcu); > synchronize_sched(); > } > +#else > +static inline void tracepoint_synchronize_unregister(void) > +{ } > +#endif > > #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS > extern int syscall_regfunc(void); > @@ -129,18 +138,32 @@ extern void syscall_unregfunc(void); > * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just > * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto". > */ > -#define __DO_TRACE(tp, proto, args, cond, rcucheck) \ > +#define __DO_TRACE(tp, proto, args, cond, rcuidle) \ > do { \ > struct tracepoint_func *it_func_ptr; \ > void *it_func; \ > void *__data; \ > + int __maybe_unused idx = 0; \ > \ > if (!(cond)) \ > return; \ > - if (rcucheck) \ > - rcu_irq_enter_irqson(); \ > - rcu_read_lock_sched_notrace(); \ > - it_func_ptr = rcu_dereference_sched((tp)->funcs); \ > + \ > + /* srcu can't be used from NMI */ \ > + if (rcuidle && in_nmi()) \ > + WARN_ON_ONCE(1); \
Why isn't the above:
WARN_ON_ONCE(rcuidle && in_nmi());
?
The rest looks fine.
-- Steve
> + \ > + /* keep srcu and sched-rcu usage consistent */ \ > + preempt_disable_notrace(); \ > + \ > + /* \ > + * For rcuidle callers, use srcu since sched-rcu \ > + * doesn't work from the idle path. \ > + */ \ > + if (rcuidle) \ > + idx = srcu_read_lock_notrace(&tracepoint_srcu); \ > + \ > + it_func_ptr = rcu_dereference_raw((tp)->funcs); \ > + \ > if (it_func_ptr) { \ > do { \ > it_func = (it_func_ptr)->func; \ > @@ -148,9 +171,11 @@ extern void syscall_unregfunc(void); > ((void(*)(proto))(it_func))(args); \ > } while ((++it_func_ptr)->func); \ > } \ > - rcu_read_unlock_sched_notrace(); \ > - if (rcucheck) \ > - rcu_irq_exit_irqson(); \ > + \ > + if (rcuidle) \ > + srcu_read_unlock_notrace(&tracepoint_srcu, idx);\ > + \ > + preempt_enable_notrace(); \ > } while (0) > >
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