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proc: rewrite next_tgid()

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* deduplicate "iter.tgid += 1" line,
  Right now it is done once inside next_tgid() itself and second time
  inside "for" loop.

* deduplicate next_tgid() call itself with different loop style:

	auto it = make_tgid_iter();
	while (next_tgid(&it)) {
		...
	}

  gcc seems to inline it twice:

  	$ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux
	add/remove: 0/1 grow/shrink: 1/0 up/down: 100/-245 (-145)
	Function                                     old     new   delta
	proc_pid_readdir                             531     631    +100
	next_tgid                                    245       -    -245

* make tgid_iter.pid_ns const
  it never changes during readdir anyway

[akpm@linux-foundation.org: remove newline]
Link: https://lore.kernel.org/20260422191745.435556-2-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan
2026-04-22 22:17:45 +03:00
committed by Andrew Morton
parent 9794de4500
commit f7027ed76d
1 changed files with 34 additions and 26 deletions
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60
fs/proc/base.c
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@@ -3543,30 +3543,42 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags)
struct tgid_iter {
unsigned int tgid;
struct task_struct *task;
struct pid_namespace *pid_ns;
struct pid_namespace *const pid_ns;
};
static struct tgid_iter next_tgid(struct tgid_iter iter)
static struct tgid_iter
make_tgid_iter(unsigned int init_tgid, struct pid_namespace *pid_ns)
{
struct pid *pid;
return (struct tgid_iter){
.tgid = init_tgid - 1,
.pid_ns = pid_ns,
};
}
if (iter.task)
put_task_struct(iter.task);
rcu_read_lock();
retry:
iter.task = NULL;
pid = find_ge_pid(iter.tgid, iter.pid_ns);
if (pid) {
iter.tgid = pid_nr_ns(pid, iter.pid_ns);
iter.task = pid_task(pid, PIDTYPE_TGID);
if (!iter.task) {
iter.tgid += 1;
goto retry;
}
get_task_struct(iter.task);
static bool next_tgid(struct tgid_iter *it)
{
if (it->task) {
put_task_struct(it->task);
it->task = NULL;
}
rcu_read_lock();
while (1) {
it->tgid += 1;
const auto pid = find_ge_pid(it->tgid, it->pid_ns);
if (pid) {
it->tgid = pid_nr_ns(pid, it->pid_ns);
it->task = pid_task(pid, PIDTYPE_TGID);
if (it->task) {
get_task_struct(it->task);
rcu_read_unlock();
return true;
}
} else {
rcu_read_unlock();
return false;
}
}
rcu_read_unlock();
return iter;
}
#define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2)
@@ -3574,7 +3586,6 @@ static struct tgid_iter next_tgid(struct tgid_iter iter)
/* for the /proc/ directory itself, after non-process stuff has been done */
int proc_pid_readdir(struct file *file, struct dir_context *ctx)
{
struct tgid_iter iter;
struct proc_fs_info *fs_info = proc_sb_info(file_inode(file)->i_sb);
struct pid_namespace *pid_ns = proc_pid_ns(file_inode(file)->i_sb);
loff_t pos = ctx->pos;
@@ -3592,12 +3603,9 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
return 0;
ctx->pos = pos = pos + 1;
}
iter.tgid = pos - TGID_OFFSET;
iter.task = NULL;
iter.pid_ns = pid_ns;
for (iter = next_tgid(iter);
iter.task;
iter.tgid += 1, iter = next_tgid(iter)) {
auto iter = make_tgid_iter(pos - TGID_OFFSET, pid_ns);
while (next_tgid(&iter)) {
char name[10 + 1];
unsigned int len;