Commit 804d6794 authored by Christian Brauner's avatar Christian Brauner
Browse files

pidfs: remove pidfs_{get,put}_pid() 

Now that we stash persistent information in struct pid there's no need
to play volatile games with pinning struct pid via dentries in pidfs.

Link: https://lore.kernel.org/20250618-work-pidfs-persistent-v2-8-98f3456fd552@kernel.org


Reviewed-by: default avatarAlexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 0f93d71b

fs/coredump.c

+0 −6
Original line number Diff line number Diff line
@@ -898,12 +898,6 @@ void do_coredump(const kernel_siginfo_t *siginfo) 
		retval = kernel_connect(socket, (struct sockaddr *)(&addr),

					addr_len, O_NONBLOCK | SOCK_COREDUMP);



		/*

		 * ... Make sure to only put our reference after connect() took

		 * its own reference keeping the pidfs entry alive ...

		 */

		pidfs_put_pid(cprm.pid);



		if (retval) {

			if (retval == -EAGAIN)

				coredump_report_failure("Coredump socket %s receive queue full", addr.sun_path);

fs/pidfs.c

+1 −34
Original line number Diff line number Diff line
@@ -895,8 +895,7 @@ static void pidfs_put_data(void *data) 
 * pidfs_register_pid - register a struct pid in pidfs

 * @pid: pid to pin

 *

 * Register a struct pid in pidfs. Needs to be paired with

 * pidfs_put_pid() to not risk leaking the pidfs dentry and inode.

 * Register a struct pid in pidfs.

 *

 * Return: On success zero, on error a negative error code is returned.

 */
@@ -1007,38 +1006,6 @@ struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags) 
	return pidfd_file;

}



/**

 * pidfs_get_pid - pin a struct pid through pidfs

 * @pid: pid to pin

 *

 * Similar to pidfs_register_pid() but only valid if the caller knows

 * there's a reference to the @pid through a dentry already that can't

 * go away.

 */

void pidfs_get_pid(struct pid *pid)

{

	if (!pid)

		return;

	WARN_ON_ONCE(!stashed_dentry_get(&pid->stashed));

}



/**

 * pidfs_put_pid - drop a pidfs reference

 * @pid: pid to drop

 *

 * Drop a reference to @pid via pidfs. This is only safe if the

 * reference has been taken via pidfs_get_pid().

 */

void pidfs_put_pid(struct pid *pid)

{

	might_sleep();



	if (!pid)

		return;

	VFS_WARN_ON_ONCE(!pid->stashed);

	dput(pid->stashed);

}



void __init pidfs_init(void)

{

	pidfs_attr_cachep = kmem_cache_create("pidfs_attr_cache", sizeof(struct pidfs_attr), 0,

include/linux/pidfs.h

+0 −2
Original line number Diff line number Diff line
@@ -14,8 +14,6 @@ void pidfs_coredump(const struct coredump_params *cprm); 
#endif

extern const struct dentry_operations pidfs_dentry_operations;

int pidfs_register_pid(struct pid *pid);

void pidfs_get_pid(struct pid *pid);

void pidfs_put_pid(struct pid *pid);

void pidfs_free_pid(struct pid *pid);



#endif /* _LINUX_PID_FS_H */

net/unix/af_unix.c

+0 −5
Original line number Diff line number Diff line
@@ -646,9 +646,6 @@ static void unix_sock_destructor(struct sock *sk) 
		return;

	}



	if (sk->sk_peer_pid)

		pidfs_put_pid(sk->sk_peer_pid);



	if (u->addr)

		unix_release_addr(u->addr);
@@ -769,7 +766,6 @@ static void drop_peercred(struct unix_peercred *peercred) 
	swap(peercred->peer_pid, pid);

	swap(peercred->peer_cred, cred);



	pidfs_put_pid(pid);

	put_pid(pid);

	put_cred(cred);

}
@@ -802,7 +798,6 @@ static void copy_peercred(struct sock *sk, struct sock *peersk) 


	spin_lock(&sk->sk_peer_lock);

	sk->sk_peer_pid = get_pid(peersk->sk_peer_pid);

	pidfs_get_pid(sk->sk_peer_pid);

	sk->sk_peer_cred = get_cred(peersk->sk_peer_cred);

	spin_unlock(&sk->sk_peer_lock);

}