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

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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: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-06-18 22:53:42 +02:00
parent 0f93d71b9d
commit 804d679449
4 changed files with 1 additions and 47 deletions
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6
fs/coredump.c
View File

@@ -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);

35
fs/pidfs.c
View File

@@ -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,

2
include/linux/pidfs.h
View File

@@ -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 */

5
net/unix/af_unix.c
View File

@@ -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);
}