[PATCH bpf v2] ftrace: fix incorrect hash size in register_ftrace_direct()

[Menglong Dong]

The maximum of the ftrace hash bits is made fls(32) in
register_ftrace_direct(), which seems illogical. So, we fix it by making
the max hash bits FTRACE_HASH_MAX_BITS instead.

Fixes: d05cb470663a ("ftrace: Fix modification of direct_function hash while in 
use")
Signed-off-by: Menglong Dong <dong...@chinatelecom.cn>
---
v2:
- thanks for Steven's advice, we fix the problem by making the max hash
  bits FTRACE_HASH_MAX_BITS instead.
---
 kernel/trace/ftrace.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1a48aedb5255..d153ad13e0e0 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5914,9 +5914,10 @@ int register_ftrace_direct(struct ftrace_ops *ops, 
unsigned long addr)
 
        /* Make a copy hash to place the new and the old entries in */
        size = hash->count + direct_functions->count;
-       if (size > 32)
-               size = 32;
-       new_hash = alloc_ftrace_hash(fls(size));
+       size = fls(size);
+       if (size > FTRACE_HASH_MAX_BITS)
+               size = FTRACE_HASH_MAX_BITS;
+       new_hash = alloc_ftrace_hash(size);
        if (!new_hash)
                goto out_unlock;
 
-- 
2.39.5