From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: adobriyan@gmail.com, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, ebiederm@xmission.com
Subject: [PATCH 2/2] proc: rewrite next_tgid()
Date: Wed, 22 Apr 2026 22:17:45 +0300 [thread overview]
Message-ID: <20260422191745.435556-2-adobriyan@gmail.com> (raw)
In-Reply-To: <20260422191745.435556-1-adobriyan@gmail.com>
* 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
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 57 +++++++++++++++++++++++++++++---------------------
1 file changed, 33 insertions(+), 24 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index f2db455dbbfd..f38ac943ec32 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3543,30 +3543,43 @@ 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,
+ };
+}
+
+static bool next_tgid(struct tgid_iter *it)
+{
+ if (it->task) {
+ put_task_struct(it->task);
+ it->task = NULL;
+ }
- 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;
+ 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;
}
- get_task_struct(iter.task);
}
- rcu_read_unlock();
- return iter;
}
#define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2)
@@ -3574,7 +3587,6 @@ 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 +3604,9 @@ 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;
--
2.52.0
next prev parent reply other threads:[~2026-04-22 19:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-22 19:17 [PATCH 1/2] proc: add tgid_iter.pid_ns member Alexey Dobriyan
2026-04-22 19:17 ` Alexey Dobriyan [this message]
-- strict thread matches above, loose matches on Subject: below --
2026-04-16 16:45 Alexey Dobriyan
2026-04-16 16:45 ` [PATCH 2/2] proc: rewrite next_tgid() Alexey Dobriyan
2026-04-16 16:43 [PATCH 1/2] proc: add tgid_iter.pid_ns member Alexey Dobriyan
2026-04-16 16:43 ` [PATCH 2/2] proc: rewrite next_tgid() Alexey Dobriyan
2025-12-26 19:55 [PATCH 1/2] proc: add tgid_iter.pid_ns member Alexey Dobriyan
2025-12-26 19:55 ` [PATCH 2/2] proc: rewrite next_tgid() Alexey Dobriyan
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