From bf6672d2143897807115645490c654245d428906 Mon Sep 17 00:00:00 2001
From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Mon, 17 Mar 2025 23:34:19 +1100
Subject: [PATCH] Revert "pidfs: ensure that PIDFS_INFO_EXIT is available"
This reverts commit b0f4119d8b2a680c8cd019f41c64e8b5444c6b83.
---
fs/pidfs.c | 54 ++++-----------------------------------------------
kernel/fork.c | 7 ++-----
2 files changed, 6 insertions(+), 55 deletions(-)
diff --git a/fs/pidfs.c b/fs/pidfs.c
index d52643cc9b16c..079a5b1b34938 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -762,49 +762,8 @@ static int pidfs_export_permission(struct handle_to_path_ctx *ctx,
return 0;
}
-static inline bool pidfs_pid_valid(struct pid *pid, const struct path *path,
- unsigned int flags)
-{
- enum pid_type type;
-
- if (flags & CLONE_PIDFD)
- return true;
-
- /*
- * Make sure that if a pidfd is created PIDFD_INFO_EXIT
- * information will be available. So after an inode for the
- * pidfd has been allocated perform another check that the pid
- * is still alive. If it is exit information is available even
- * if the task gets reaped before the pidfd is returned to
- * userspace. The only exception is CLONE_PIDFD where no task
- * linkage has been established for @pid yet and the kernel is
- * in the middle of process creation so there's nothing for
- * pidfs to miss.
- */
- if (flags & PIDFD_THREAD)
- type = PIDTYPE_PID;
- else
- type = PIDTYPE_TGID;
-
- /*
- * Since pidfs_exit() is called before struct pid's task linkage
- * is removed the case where the task got reaped but a dentry
- * was already attached to struct pid and exit information was
- * recorded and published can be handled correctly.
- */
- if (unlikely(!pid_has_task(pid, type))) {
- struct inode *inode = d_inode(path->dentry);
- return !!READ_ONCE(pidfs_i(inode)->exit_info);
- }
-
- return true;
-}
-
static struct file *pidfs_export_open(struct path *path, unsigned int oflags)
{
- if (!pidfs_pid_valid(d_inode(path->dentry)->i_private, path, oflags))
- return ERR_PTR(-ESRCH);
-
/*
* Clear O_LARGEFILE as open_by_handle_at() forces it and raise
* O_RDWR as pidfds always are.
@@ -870,24 +829,19 @@ struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags)
{
struct file *pidfd_file;
- struct path path __free(path_put) = {};
- unsigned int pidfd_flags = (flags & ~CLONE_PIDFD);
+ struct path path;
int ret;
- BUILD_BUG_ON(O_DSYNC != CLONE_PIDFD);
-
ret = path_from_stashed(&pid->stashed, pidfs_mnt, get_pid(pid), &path);
if (ret < 0)
return ERR_PTR(ret);
- if (!pidfs_pid_valid(pid, &path, flags))
- return ERR_PTR(-ESRCH);
-
- pidfd_file = dentry_open(&path, pidfd_flags, current_cred());
+ pidfd_file = dentry_open(&path, flags, current_cred());
/* Raise PIDFD_THREAD explicitly as do_dentry_open() strips it. */
if (!IS_ERR(pidfd_file))
- pidfd_file->f_flags |= (pidfd_flags & PIDFD_THREAD);
+ pidfd_file->f_flags |= (flags & PIDFD_THREAD);
+ path_put(&path);
return pidfd_file;
}
diff --git a/kernel/fork.c b/kernel/fork.c
index eb6bab188d1c9..081dec23ff908 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2456,11 +2456,8 @@ __latent_entropy struct task_struct *copy_process(
if (clone_flags & CLONE_PIDFD) {
int flags = (clone_flags & CLONE_THREAD) ? PIDFD_THREAD : 0;
- /*
- * Note that no task has been attached to @pid yet indicate
- * that via CLONE_PIDFD.
- */
- retval = __pidfd_prepare(pid, flags | CLONE_PIDFD, &pidfile);
+ /* Note that no task has been attached to @pid yet. */
+ retval = __pidfd_prepare(pid, flags, &pidfile);
if (retval < 0)
goto bad_fork_free_pid;
pidfd = retval;
--
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