From: "Steven Rostedt (Red Hat)" 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/20141214164104.307127356@goodmis.org Reviewed-by: Paul E. McKenney Suggested-by: Thomas Gleixner Tested-by: Thomas Gleixner Acked-by: Thomas Gleixner Signed-off-by: Steven Rostedt --- 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/