On Sun, Dec 14, 2014 at 03:16:10PM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (Red Hat)" <[email protected]> > > Enabling tracepoints at boot up can be very useful. The tracepoint > can be initialized right after RCU has been. There's no need to > wait for the early_initcall() to be called. That's too late for some > things that can use tracepoints for debugging. Move the logic to > enable tracepoints out of the initcalls and into init/main.c to > right after rcu_init(). > > This also allows trace_printk() to be used early too. > > Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos > Link: http://lkml.kernel.org/r/[email protected] > > Suggested-by: Thomas Gleixner <[email protected]> > Signed-off-by: Steven Rostedt <[email protected]>
>From an RCU perspective: Reviewed-by: Paul E. McKenney <[email protected]> > --- > include/linux/ftrace.h | 6 ++++++ > init/main.c | 4 ++++ > kernel/trace/trace.c | 8 +++++++- > kernel/trace/trace.h | 13 +++++++++++++ > kernel/trace/trace_events.c | 10 ++++++++-- > kernel/trace/trace_syscalls.c | 7 ++----- > 6 files changed, 40 insertions(+), 8 deletions(-) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index ed501953f0b2..f4bc14b7d444 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -39,6 +39,12 @@ > # define FTRACE_FORCE_LIST_FUNC 0 > #endif > > +/* Main tracing buffer and events set up */ > +#ifdef CONFIG_TRACING > +void trace_init(void); > +#else > +static inline void trace_init(void) { } > +#endif > > struct module; > struct ftrace_hash; > diff --git a/init/main.c b/init/main.c > index 800a0daede7e..70687069f8e2 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -577,6 +577,10 @@ asmlinkage __visible void __init start_kernel(void) > local_irq_disable(); > idr_init_cache(); > rcu_init(); > + > + /* trace_printk() and trace points may be used after this */ > + trace_init(); > + > context_tracking_init(); > radix_tree_init(); > /* init some links before init_ISA_irqs() */ > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 4ceb2546c7ef..ec3ca694665f 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -6876,6 +6876,13 @@ out: > return ret; > } > > +void __init trace_init(void) > +{ > + tracer_alloc_buffers(); > + init_ftrace_syscalls(); > + trace_event_init(); > +} > + > __init static int clear_boot_tracer(void) > { > /* > @@ -6895,6 +6902,5 @@ __init static int clear_boot_tracer(void) > return 0; > } > > -early_initcall(tracer_alloc_buffers); > fs_initcall(tracer_init_debugfs); > late_initcall(clear_boot_tracer); > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 3255dfb054a0..c138c149d6ef 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -1301,4 +1301,17 @@ int perf_ftrace_event_register(struct > ftrace_event_call *call, > #define perf_ftrace_event_register NULL > #endif > > +#ifdef CONFIG_FTRACE_SYSCALLS > +void init_ftrace_syscalls(void); > +#else > +static inline void init_ftrace_syscalls(void) { } > +#endif > + > +#ifdef CONFIG_EVENT_TRACING > +void trace_event_init(void); > +#else > +static inline void __init trace_event_init(void) { } > +#endif > + > + > #endif /* _LINUX_KERNEL_TRACE_H */ > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index f9d0cbe014b7..fd9deb0e03f0 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -2477,8 +2477,14 @@ static __init int event_trace_init(void) > #endif > return 0; > } > -early_initcall(event_trace_memsetup); > -core_initcall(event_trace_enable); > + > +void __init trace_event_init(void) > +{ > + event_trace_memsetup(); > + init_ftrace_syscalls(); > + event_trace_enable(); > +} > + > fs_initcall(event_trace_init); > > #ifdef CONFIG_FTRACE_STARTUP_TEST > diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c > index a72f3d8d813e..ec239771c175 100644 > --- a/kernel/trace/trace_syscalls.c > +++ b/kernel/trace/trace_syscalls.c > @@ -514,7 +514,7 @@ unsigned long __init __weak arch_syscall_addr(int nr) > return (unsigned long)sys_call_table[nr]; > } > > -static int __init init_ftrace_syscalls(void) > +void __init init_ftrace_syscalls(void) > { > struct syscall_metadata *meta; > unsigned long addr; > @@ -524,7 +524,7 @@ static int __init init_ftrace_syscalls(void) > GFP_KERNEL); > if (!syscalls_metadata) { > WARN_ON(1); > - return -ENOMEM; > + return; > } > > for (i = 0; i < NR_syscalls; i++) { > @@ -536,10 +536,7 @@ static int __init init_ftrace_syscalls(void) > meta->syscall_nr = i; > syscalls_metadata[i] = meta; > } > - > - return 0; > } > -early_initcall(init_ftrace_syscalls); > > #ifdef CONFIG_PERF_EVENTS > > -- > 2.1.3 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
