Thread (27 messages) 27 messages, 3 authors, 2018-03-28

Re: [PATCH v7 bpf-next 06/10] tracepoint: compute num_args at build time

From: Steven Rostedt <rostedt@goodmis.org>
Date: 2018-03-28 19:38:32
Also in: linux-api

On Wed, 28 Mar 2018 15:32:20 -0400
Steven Rostedt [off-list ref] wrote:
quoted hunk ↗ jump to hunk
-#define __DO_TRACE(tp, proto, args, cond, rcucheck)			\
+#define __DO_TRACE(name, proto, args, cond, rcucheck)			\
 	do {								\
 		struct tracepoint_func *it_func_ptr;			\
 		void *it_func;						\
@@ -140,7 +140,7 @@ extern void syscall_unregfunc(void);
 		if (rcucheck)						\
 			rcu_irq_enter_irqson();				\
 		rcu_read_lock_sched_notrace();				\
-		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\
+		it_func_ptr = rcu_dereference_sched(__trace_##name##_funcs); \
What we lose in data size, we may make up for in text (which is even
more important). This will remove a dereference in the hot path.

I'll make a few builds and run size on the vmlinux images to see how
this pans out.

-- Steve

 		if (it_func_ptr) {					\
 			do {						\
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