linux-ext4 - [PATCH 10/13] procfs: make freeing proc_fs

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Message-Id: <20240204021739.1157830-10-viro@zeniv.linux.org.uk>
Date: Sun,  4 Feb 2024 02:17:36 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: linux-fsdevel@...r.kernel.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	Christian Brauner <brauner@...nel.org>,
	linux-ext4@...r.kernel.org,
	linux-nfs@...r.kernel.org,
	Miklos Szeredi <miklos@...redi.hu>,
	linux-cifs@...r.kernel.org
Subject: [PATCH 10/13] procfs: make freeing proc_fs_info rcu-delayed

makes proc_pid_ns() safe from rcu pathwalk (put_pid_ns()
is still synchronous, but that's not a problem - it does
rcu-delay everything that needs to be)

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/proc/root.c          | 2 +-
 include/linux/proc_fs.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/proc/root.c b/fs/proc/root.c
index b55dbc70287b..06a297a27ba3 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -271,7 +271,7 @@ static void proc_kill_sb(struct super_block *sb)
 
 	kill_anon_super(sb);
 	put_pid_ns(fs_info->pid_ns);
-	kfree(fs_info);
+	kfree_rcu(fs_info, rcu);
 }
 
 static struct file_system_type proc_fs_type = {
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index de407e7c3b55..0b2a89854440 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -65,6 +65,7 @@ struct proc_fs_info {
 	kgid_t pid_gid;
 	enum proc_hidepid hide_pid;
 	enum proc_pidonly pidonly;
+	struct rcu_head rcu;
 };
 
 static inline struct proc_fs_info *proc_sb_info(struct super_block *sb)
-- 
2.39.2