On Thu, 26 Jul 2018 16:50:43 -0700
Joel Fernandes <j...@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)
>
>
