[PATCH 2/5] exec: kill ->load_binary != NULL check in search_binary_handler()

Oleg Nesterov
2013-08-02T19:33:07Z

search_binary_handler() checks ->load_binary != NULL for no reason,
this method should be always defined. Turn this check into WARN_ON()
and move it into __register_binfmt().

Also, kill the function pointer. The current code looks confusing,
as if ->load_binary can go away after read_unlock(&binfmt_lock).
But we rely on module_get(fmt->module), this fmt can't be changed
or unregistered, otherwise this code is buggy anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
fs/exec.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index ef70320..9f41e7d 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -74,6 +74,8 @@ static DEFINE_RWLOCK(binfmt_lock);
void __register_binfmt(struct linux_binfmt * fmt, int insert)
{
BUG_ON(!fmt);
+ if (WARN_ON(!fmt->load_binary))
+ return;
write_lock(&binfmt_lock);
insert ? list_add(&fmt->lh, &formats) :
list_add_tail(&fmt->lh, &formats);
@@ -1389,14 +1391,11 @@ int search_binary_handler(struct linux_binprm *bprm)
for (try=0; try<2; try++) {
read_lock(&binfmt_lock);
list_for_each_entry(fmt, &formats, lh) {
- int (*fn)(struct linux_binprm *) = fmt->load_binary;
- if (!fn)
- continue;
if (!try_module_get(fmt->module))
continue;
read_unlock(&binfmt_lock);
bprm->recursion_depth++;
- retval = fn(bprm);
+ retval = fmt->load_binary(bprm);
bprm->recursion_depth--;
if (retval >= 0) {
put_binfmt(fmt);
--
1.5.5.1