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authorAlexey Dobriyan <adobriyan@gmail.com>2019-03-11 23:28:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-12 10:04:01 -0700
commitd5a572a4cb1e484d8d8c79bdfd16aaa18fa1470b (patch)
tree60509f727ebe752228ef7a7f3f19b704ae6a5780
parentb5420237ec817b0b5f729a674c81ace0865c3b3b (diff)
proc: calculate end pointer for /proc/*/* lookup at compile time
Compilers like to transform loops like for (i = 0; i < n; i++) { [use p[i]] } into for (p = p0; p < end; p++) { ... } Do it by hand, so that it results in overall simpler loop and smaller code. Space savings: $ ./scripts/bloat-o-meter ../vmlinux-001 ../obj/vmlinux add/remove: 0/0 grow/shrink: 2/1 up/down: 4/-9 (-5) Function old new delta proc_tid_base_lookup 17 19 +2 proc_tgid_base_lookup 17 19 +2 proc_pident_lookup 179 170 -9 The same could be done to proc_pident_readdir(), but the code becomes bigger for some reason. [sfr@canb.auug.org.au: merge fix for proc_pident_lookup() API change] Link: http://lkml.kernel.org/r/20190131160135.4a8ae70b@canb.auug.org.au Link: http://lkml.kernel.org/r/20190114200422.GB9680@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: James Morris <jmorris@namei.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/base.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 5ab1849971b4..1b548d060d28 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2459,11 +2459,10 @@ static struct dentry *proc_pident_instantiate(struct dentry *dentry,
static struct dentry *proc_pident_lookup(struct inode *dir,
struct dentry *dentry,
- const struct pid_entry *ents,
- unsigned int nents)
+ const struct pid_entry *p,
+ const struct pid_entry *end)
{
struct task_struct *task = get_proc_task(dir);
- const struct pid_entry *p, *last;
struct dentry *res = ERR_PTR(-ENOENT);
if (!task)
@@ -2473,8 +2472,7 @@ static struct dentry *proc_pident_lookup(struct inode *dir,
* Yes, it does not scale. And it should not. Don't add
* new entries into /proc/<tgid>/ without very good reasons.
*/
- last = &ents[nents];
- for (p = ents; p < last; p++) {
+ for (; p < end; p++) {
if (p->len != dentry->d_name.len)
continue;
if (!memcmp(dentry->d_name.name, p->name, p->len)) {
@@ -2610,7 +2608,7 @@ static struct dentry *proc_##LSM##_attr_dir_lookup(struct inode *dir, \
{ \
return proc_pident_lookup(dir, dentry, \
LSM##_attr_dir_stuff, \
- ARRAY_SIZE(LSM##_attr_dir_stuff)); \
+ LSM##_attr_dir_stuff + ARRAY_SIZE(LSM##_attr_dir_stuff)); \
} \
\
static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \
@@ -2655,7 +2653,8 @@ static struct dentry *proc_attr_dir_lookup(struct inode *dir,
struct dentry *dentry, unsigned int flags)
{
return proc_pident_lookup(dir, dentry,
- attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
+ attr_dir_stuff,
+ attr_dir_stuff + ARRAY_SIZE(attr_dir_stuff));
}
static const struct inode_operations proc_attr_dir_inode_operations = {
@@ -3091,7 +3090,8 @@ static const struct file_operations proc_tgid_base_operations = {
static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
return proc_pident_lookup(dir, dentry,
- tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
+ tgid_base_stuff,
+ tgid_base_stuff + ARRAY_SIZE(tgid_base_stuff));
}
static const struct inode_operations proc_tgid_base_inode_operations = {
@@ -3463,7 +3463,8 @@ static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
return proc_pident_lookup(dir, dentry,
- tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
+ tid_base_stuff,
+ tid_base_stuff + ARRAY_SIZE(tid_base_stuff));
}
static const struct file_operations proc_tid_base_operations = {