percpu: make percpu symbols in tracer unique

This patch updates percpu related symbols in kernel tracer such that
percpu symbols are unique and don't clash with local symbols.  This
serves two purposes of decreasing the possibility of global percpu
symbol collision and allowing dropping per_cpu__ prefix from percpu
symbols.

* kernel/trace/trace.c: s/max_data/max_tr_data/
* kernel/trace/trace_hw_branches: s/tracer/hwb_tracer/, s/buffer/hwb_buffer/

Partly based on Rusty Russell's "alloc_percpu: rename percpu vars
which cause name clashes" patch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>

kernel/trace/trace.c

@@ -203,7 +203,7 @@ cycle_t ftrace_now(int cpu)
  */
 static struct trace_array	max_tr;
 
-static DEFINE_PER_CPU(struct trace_array_cpu, max_data);
+static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
 
 /* tracer_enabled is used to toggle activation of a tracer */
 static int			tracer_enabled = 1;
@@ -4426,7 +4426,7 @@ __init static int tracer_alloc_buffers(void)
 	/* Allocate the first page for all buffers */
 	for_each_tracing_cpu(i) {
 		global_trace.data[i] = &per_cpu(global_trace_cpu, i);
-		max_tr.data[i] = &per_cpu(max_data, i);
+		max_tr.data[i] = &per_cpu(max_tr_data, i);
 	}
 
 	trace_init_cmdlines();

kernel/trace/trace_hw_branches.c

@@ -20,10 +20,10 @@
 
 #define BTS_BUFFER_SIZE (1 << 13)
 
-static DEFINE_PER_CPU(struct bts_tracer *, tracer);
-static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], buffer);
+static DEFINE_PER_CPU(struct bts_tracer *, hwb_tracer);
+static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], hwb_buffer);
 
-#define this_tracer per_cpu(tracer, smp_processor_id())
+#define this_tracer per_cpu(hwb_tracer, smp_processor_id())
 
 static int trace_hw_branches_enabled __read_mostly;
 static int trace_hw_branches_suspended __read_mostly;
@@ -32,12 +32,13 @@ static struct trace_array *hw_branch_trace __read_mostly;
 
 static void bts_trace_init_cpu(int cpu)
 {
-	per_cpu(tracer, cpu) =
-		ds_request_bts_cpu(cpu, per_cpu(buffer, cpu), BTS_BUFFER_SIZE,
-				   NULL, (size_t)-1, BTS_KERNEL);
+	per_cpu(hwb_tracer, cpu) =
+		ds_request_bts_cpu(cpu, per_cpu(hwb_buffer, cpu),
+				   BTS_BUFFER_SIZE, NULL, (size_t)-1,
+				   BTS_KERNEL);
 
-	if (IS_ERR(per_cpu(tracer, cpu)))
-		per_cpu(tracer, cpu) = NULL;
+	if (IS_ERR(per_cpu(hwb_tracer, cpu)))
+		per_cpu(hwb_tracer, cpu) = NULL;
 }
 
 static int bts_trace_init(struct trace_array *tr)
@@ -51,7 +52,7 @@ static int bts_trace_init(struct trace_array *tr)
 	for_each_online_cpu(cpu) {
 		bts_trace_init_cpu(cpu);
 
-		if (likely(per_cpu(tracer, cpu)))
+		if (likely(per_cpu(hwb_tracer, cpu)))
 			trace_hw_branches_enabled = 1;
 	}
 	trace_hw_branches_suspended = 0;
@@ -67,9 +68,9 @@ static void bts_trace_reset(struct trace_array *tr)
 
 	get_online_cpus();
 	for_each_online_cpu(cpu) {
-		if (likely(per_cpu(tracer, cpu))) {
-			ds_release_bts(per_cpu(tracer, cpu));
-			per_cpu(tracer, cpu) = NULL;
+		if (likely(per_cpu(hwb_tracer, cpu))) {
+			ds_release_bts(per_cpu(hwb_tracer, cpu));
+			per_cpu(hwb_tracer, cpu) = NULL;
 		}
 	}
 	trace_hw_branches_enabled = 0;
@@ -83,8 +84,8 @@ static void bts_trace_start(struct trace_array *tr)
 
 	get_online_cpus();
 	for_each_online_cpu(cpu)
-		if (likely(per_cpu(tracer, cpu)))
-			ds_resume_bts(per_cpu(tracer, cpu));
+		if (likely(per_cpu(hwb_tracer, cpu)))
+			ds_resume_bts(per_cpu(hwb_tracer, cpu));
 	trace_hw_branches_suspended = 0;
 	put_online_cpus();
 }
@@ -95,8 +96,8 @@ static void bts_trace_stop(struct trace_array *tr)
 
 	get_online_cpus();
 	for_each_online_cpu(cpu)
-		if (likely(per_cpu(tracer, cpu)))
-			ds_suspend_bts(per_cpu(tracer, cpu));
+		if (likely(per_cpu(hwb_tracer, cpu)))
+			ds_suspend_bts(per_cpu(hwb_tracer, cpu));
 	trace_hw_branches_suspended = 1;
 	put_online_cpus();
 }
@@ -114,16 +115,16 @@ static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
 			bts_trace_init_cpu(cpu);
 
 			if (trace_hw_branches_suspended &&
-			    likely(per_cpu(tracer, cpu)))
-				ds_suspend_bts(per_cpu(tracer, cpu));
+			    likely(per_cpu(hwb_tracer, cpu)))
+				ds_suspend_bts(per_cpu(hwb_tracer, cpu));
 		}
 		break;
 
 	case CPU_DOWN_PREPARE:
 		/* The notification is sent with interrupts enabled. */
-		if (likely(per_cpu(tracer, cpu))) {
-			ds_release_bts(per_cpu(tracer, cpu));
-			per_cpu(tracer, cpu) = NULL;
+		if (likely(per_cpu(hwb_tracer, cpu))) {
+			ds_release_bts(per_cpu(hwb_tracer, cpu));
+			per_cpu(hwb_tracer, cpu) = NULL;
 		}
 	}
 
@@ -256,8 +257,8 @@ static void trace_bts_prepare(struct trace_iterator *iter)
 
 	get_online_cpus();
 	for_each_online_cpu(cpu)
-		if (likely(per_cpu(tracer, cpu)))
-			ds_suspend_bts(per_cpu(tracer, cpu));
+		if (likely(per_cpu(hwb_tracer, cpu)))
+			ds_suspend_bts(per_cpu(hwb_tracer, cpu));
 	/*
 	 * We need to collect the trace on the respective cpu since ftrace
 	 * implicitly adds the record for the current cpu.
@@ -266,8 +267,8 @@ static void trace_bts_prepare(struct trace_iterator *iter)
 	on_each_cpu(trace_bts_cpu, iter->tr, 1);
 
 	for_each_online_cpu(cpu)
-		if (likely(per_cpu(tracer, cpu)))
-			ds_resume_bts(per_cpu(tracer, cpu));
+		if (likely(per_cpu(hwb_tracer, cpu)))
+			ds_resume_bts(per_cpu(hwb_tracer, cpu));
 	put_online_cpus();
 }