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Message-ID: <20070725105646.GA11047@localhost.sw.ru>
Date: Wed, 25 Jul 2007 14:56:46 +0400
From: Alexey Dobriyan <adobriyan@...ru>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/2] Use list_head in binfmt handling
On Tue, Jul 24, 2007 at 10:16:44PM -0700, akpm@...ux-foundation.org wrote:
> arch/sparc64/kernel/binfmt_aout32.c:41: warning: missing braces around initializer
> arch/sparc64/kernel/binfmt_aout32.c:41: warning: (near initialization for `aout32_format.lh')
> arch/sparc64/kernel/binfmt_aout32.c:41: warning: initialization from incompatible pointer type
> arch/sparc64/kernel/binfmt_aout32.c:41: warning: initialization from incompatible pointer type
> arch/sparc64/kernel/binfmt_aout32.c:41: warning: initialization from incompatible pointer type
> arch/sparc64/kernel/binfmt_aout32.c:41: warning: initialization from incompatible pointer type
> arch/sparc64/kernel/binfmt_aout32.c:43: warning: initialization makes pointer from integer without a cast
> --- a/arch/sparc64/kernel/binfmt_aout32.c~use-list_head-in-binfmt-handling-fix
> +++ a/arch/sparc64/kernel/binfmt_aout32.c
> @@ -38,8 +38,12 @@ static int load_aout32_library(struct fi
> static int aout32_core_dump(long signr, struct pt_regs * regs, struct file *file);
>
> static struct linux_binfmt aout32_format = {
> - NULL, THIS_MODULE, load_aout32_binary, load_aout32_library, aout32_core_dump,
> - PAGE_SIZE
> + .lh = LIST_HEAD_INIT(aout32_format.lh),
> + .module = THIS_MODULE,
> + .load_binary = load_aout32_binary,
> + .load_shlib = load_aout32_library,
> + .core_dump = aout32_core_dump,
> + .min_coredump = PAGE_SIZE,
> };
Doh! Thanks, Andrew.
list_head initialization is unneeded, because register_binfmt() will
reinitialize it anyway.
Here is final version which was test-compiled on sparc64 and on mips
(after irixelf.c BROKEN removal):
[PATCH 1/2] Use list_head in binfmt handling
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 <adobriyan@...ru>
---
arch/mips/kernel/irixelf.c | 7 +++++--
arch/sparc64/kernel/binfmt_aout32.c | 7 +++++--
fs/exec.c | 34 ++++++----------------------------
include/linux/binfmts.h | 2 +-
4 files changed, 17 insertions(+), 33 deletions(-)
--- a/arch/mips/kernel/irixelf.c
+++ b/arch/mips/kernel/irixelf.c
@@ -47,8 +47,11 @@ static int irix_core_dump(long signr, struct pt_regs * regs,
struct file *file);
static struct linux_binfmt irix_format = {
- NULL, THIS_MODULE, load_irix_binary, load_irix_library,
- irix_core_dump, PAGE_SIZE
+ .module = THIS_MODULE,
+ .load_binary = load_irix_binary,
+ .load_shlib = load_irix_library,
+ .core_dump = irix_core_dump,
+ .min_coredump = PAGE_SIZE,
};
/* Debugging routines. */
--- a/arch/sparc64/kernel/binfmt_aout32.c
+++ b/arch/sparc64/kernel/binfmt_aout32.c
@@ -38,8 +38,11 @@ static int load_aout32_library(struct file*);
static int aout32_core_dump(long signr, struct pt_regs * regs, struct file *file);
static struct linux_binfmt aout32_format = {
- NULL, THIS_MODULE, load_aout32_binary, load_aout32_library, aout32_core_dump,
- PAGE_SIZE
+ .module = THIS_MODULE,
+ .load_binary = load_aout32_binary,
+ .load_shlib = load_aout32_library,
+ .core_dump = aout32_core_dump,
+ .min_coredump = PAGE_SIZE,
};
static void set_brk(unsigned long start, unsigned long end)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -67,27 +67,15 @@ 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;
}
@@ -96,20 +84,10 @@ 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);
@@ -156,7 +134,7 @@ 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))
@@ -1290,7 +1268,7 @@ 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
@@ -63,7 +63,7 @@ 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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