[PATCH v2 3/3] ftrace: Get rid of ftrace_profile_bits

[Namhyung Kim <namhyung@kernel.org>]

From: Namhyung Kim <namhyung.kim@lge.com>

It seems that function profiler's hash size is fixed at 1024.  Add and
use FTRACE_PROFILE_HASH_BITS instead and update hash size macro.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d38ad7145f2f..78f4398cb608 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -486,7 +486,6 @@ struct ftrace_profile_stat {
 #define PROFILES_PER_PAGE					\
 	(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
 
-static int ftrace_profile_bits __read_mostly;
 static int ftrace_profile_enabled __read_mostly;
 
 /* ftrace_profile_lock - synchronize the enable and disable of the profiler */
@@ -494,7 +493,8 @@ static DEFINE_MUTEX(ftrace_profile_lock);
 
 static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
 
-#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
+#define FTRACE_PROFILE_HASH_BITS 10
+#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)
 
 static void *
 function_stat_next(void *v, int idx)
@@ -724,13 +724,6 @@ static int ftrace_profile_init_cpu(int cpu)
 	if (!stat->hash)
 		return -ENOMEM;
 
-	if (!ftrace_profile_bits) {
-		size--;
-
-		for (; size; size >>= 1)
-			ftrace_profile_bits++;
-	}
-
 	/* Preallocate the function profiling pages */
 	if (ftrace_profile_pages_init(stat) < 0) {
 		kfree(stat->hash);
@@ -764,7 +757,7 @@ ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
 	struct hlist_node *n;
 	unsigned long key;
 
-	key = hash_long(ip, ftrace_profile_bits);
+	key = hash_long(ip, FTRACE_PROFILE_HASH_BITS);
 	hhd = &stat->hash[key];
 
 	if (hlist_empty(hhd))
@@ -783,7 +776,7 @@ static void ftrace_add_profile(struct ftrace_profile_stat *stat,
 {
 	unsigned long key;
 
-	key = hash_long(rec->ip, ftrace_profile_bits);
+	key = hash_long(rec->ip, FTRACE_PROFILE_HASH_BITS);
 	hlist_add_head_rcu(&rec->node, &stat->hash[key]);
 }
 
-- 
1.7.11.7