tracing: Do not limit the size of the number of CPU buffers

The tracing per_cpu buffers were limited to 999 CPUs for a mear
savings in stack space of a char array. Up the array to 30 characters
which is more than enough to hold a 64 bit number.
Reported-by: Robin Holt <holt@sgi.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -3996,13 +3996,9 @@ static void tracing_init_debugfs_percpu(long cpu)
 {
 	struct dentry *d_percpu = tracing_dentry_percpu();
 	struct dentry *d_cpu;
-	/* strlen(cpu) + MAX(log10(cpu)) + '\0' */
-	char cpu_dir[7];
+	char cpu_dir[30]; /* 30 characters should be more than enough */
 
-	if (cpu > 999 || cpu < 0)
-		return;
-
-	sprintf(cpu_dir, "cpu%ld", cpu);
+	snprintf(cpu_dir, 30, "cpu%ld", cpu);
 	d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
 	if (!d_cpu) {
 		pr_warning("Could not create debugfs '%s' entry\n", cpu_dir);