Switch single-linked binfmt formats list to usual list_head's.
This leads to one-liners in register_binfmt() and unregister_binfmt().
The downside is one pointer more in struct linux_binfmt. This is not a
problem, since the set of registered binfmts on typical box is very small
(ELF + something distro enabled for you).
Test-booted, played with executable .txt files, modprobe/rmmod binfmt_misc.
Signed-off-by: Alexey Dobriyan <[EMAIL PROTECTED]>
---
fs/exec.c | 34 ++++++----------------------------
include/linux/binfmts.h | 3 +--
2 files changed, 7 insertions(+), 30 deletions(-)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -66,27 +66,15 @@ int suid_dumpable = 0;
EXPORT_SYMBOL(suid_dumpable);
/* The maximal length of core_pattern is also specified in sysctl.c */
-static struct linux_binfmt *formats;
+static LIST_HEAD(formats);
static DEFINE_RWLOCK(binfmt_lock);
int register_binfmt(struct linux_binfmt * fmt)
{
- struct linux_binfmt ** tmp = &formats;
-
if (!fmt)
return -EINVAL;
- if (fmt->next)
- return -EBUSY;
write_lock(&binfmt_lock);
- while (*tmp) {
- if (fmt == *tmp) {
- write_unlock(&binfmt_lock);
- return -EBUSY;
- }
- tmp = &(*tmp)->next;
- }
- fmt->next = formats;
- formats = fmt;
+ list_add(&fmt->lh, &formats);
write_unlock(&binfmt_lock);
return 0;
}
@@ -95,20 +83,10 @@ EXPORT_SYMBOL(register_binfmt);
int unregister_binfmt(struct linux_binfmt * fmt)
{
- struct linux_binfmt ** tmp = &formats;
-
write_lock(&binfmt_lock);
- while (*tmp) {
- if (fmt == *tmp) {
- *tmp = fmt->next;
- fmt->next = NULL;
- write_unlock(&binfmt_lock);
- return 0;
- }
- tmp = &(*tmp)->next;
- }
+ list_del(&fmt->lh);
write_unlock(&binfmt_lock);
- return -EINVAL;
+ return 0;
}
EXPORT_SYMBOL(unregister_binfmt);
@@ -155,7 +133,7 @@ asmlinkage long sys_uselib(const char __user * library)
struct linux_binfmt * fmt;
read_lock(&binfmt_lock);
- for (fmt = formats ; fmt ; fmt = fmt->next) {
+ list_for_each_entry(fmt, &formats, lh) {
if (!fmt->load_shlib)
continue;
if (!try_module_get(fmt->module))
@@ -1097,7 +1075,7 @@ int search_binary_handler(struct linux_binprm
*bprm,struct pt_regs *regs)
retval = -ENOENT;
for (try=0; try<2; try++) {
read_lock(&binfmt_lock);
- for (fmt = formats ; fmt ; fmt = fmt->next) {
+ list_for_each_entry(fmt, &formats, lh) {
int (*fn)(struct linux_binprm *, struct pt_regs *) =
fmt->load_binary;
if (!fn)
continue;
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -55,7 +55,7 @@ struct linux_binprm{
* linux accepts.
*/
struct linux_binfmt {
- struct linux_binfmt * next;
+ struct list_head lh;
struct module *module;
int (*load_binary)(struct linux_binprm *, struct pt_regs * regs);
int (*load_shlib)(struct file *);
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