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From:   Aleksa Sarai <cyphar@cyphar.com>
To:     Al Viro <viro@zeniv.linux.org.uk>,
        Jeff Layton <jlayton@kernel.org>,
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Subject: [PATCH RESEND v17 02/13] nsfs: clean-up ns_get_path() signature to return int
Date:   Wed, 20 Nov 2019 16:06:20 +1100
Message-Id: <20191120050631.12816-3-cyphar@cyphar.com>
In-Reply-To: <20191120050631.12816-1-cyphar@cyphar.com>
References: <20191120050631.12816-1-cyphar@cyphar.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

ns_get_path() and ns_get_path_cb() only ever return either NULL or an
ERR_PTR. It is far more idiomatic to simply return an integer, and it
makes all of the callers of ns_get_path() more straightforward to read.

Fixes: e149ed2b805f ("take the targets of /proc/*/ns/* symlinks to separate fs")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
---
 fs/nsfs.c               | 29 ++++++++++++++---------------
 fs/proc/namespaces.c    |  6 +++---
 include/linux/proc_ns.h |  4 ++--
 kernel/bpf/offload.c    | 12 ++++++------
 kernel/events/core.c    |  2 +-
 5 files changed, 26 insertions(+), 27 deletions(-)

diff --git a/fs/nsfs.c b/fs/nsfs.c
index a0431642c6b5..f3d2833c5781 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -52,7 +52,7 @@ static void nsfs_evict(struct inode *inode)
 	ns->ops->put(ns);
 }
 
-static void *__ns_get_path(struct path *path, struct ns_common *ns)
+static int __ns_get_path(struct path *path, struct ns_common *ns)
 {
 	struct vfsmount *mnt = nsfs_mnt;
 	struct dentry *dentry;
@@ -71,13 +71,13 @@ static void *__ns_get_path(struct path *path, struct ns_common *ns)
 got_it:
 	path->mnt = mntget(mnt);
 	path->dentry = dentry;
-	return NULL;
+	return 0;
 slow:
 	rcu_read_unlock();
 	inode = new_inode_pseudo(mnt->mnt_sb);
 	if (!inode) {
 		ns->ops->put(ns);
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 	}
 	inode->i_ino = ns->inum;
 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
@@ -89,7 +89,7 @@ static void *__ns_get_path(struct path *path, struct ns_common *ns)
 	dentry = d_alloc_anon(mnt->mnt_sb);
 	if (!dentry) {
 		iput(inode);
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 	}
 	d_instantiate(dentry, inode);
 	dentry->d_fsdata = (void *)ns->ops;
@@ -98,23 +98,22 @@ static void *__ns_get_path(struct path *path, struct ns_common *ns)
 		d_delete(dentry);	/* make sure ->d_prune() does nothing */
 		dput(dentry);
 		cpu_relax();
-		return ERR_PTR(-EAGAIN);
+		return -EAGAIN;
 	}
 	goto got_it;
 }
 
-void *ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
+int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
 		     void *private_data)
 {
-	void *ret;
+	int ret;
 
 	do {
 		struct ns_common *ns = ns_get_cb(private_data);
 		if (!ns)
-			return ERR_PTR(-ENOENT);
-
+			return -ENOENT;
 		ret = __ns_get_path(path, ns);
-	} while (ret == ERR_PTR(-EAGAIN));
+	} while (ret == -EAGAIN);
 
 	return ret;
 }
@@ -131,7 +130,7 @@ static struct ns_common *ns_get_path_task(void *private_data)
 	return args->ns_ops->get(args->task);
 }
 
-void *ns_get_path(struct path *path, struct task_struct *task,
+int ns_get_path(struct path *path, struct task_struct *task,
 		  const struct proc_ns_operations *ns_ops)
 {
 	struct ns_get_path_task_args args = {
@@ -147,7 +146,7 @@ int open_related_ns(struct ns_common *ns,
 {
 	struct path path = {};
 	struct file *f;
-	void *err;
+	int err;
 	int fd;
 
 	fd = get_unused_fd_flags(O_CLOEXEC);
@@ -164,11 +163,11 @@ int open_related_ns(struct ns_common *ns,
 		}
 
 		err = __ns_get_path(&path, relative);
-	} while (err == ERR_PTR(-EAGAIN));
+	} while (err == -EAGAIN);
 
-	if (IS_ERR(err)) {
+	if (err) {
 		put_unused_fd(fd);
-		return PTR_ERR(err);
+		return err;
 	}
 
 	f = dentry_open(&path, O_RDONLY, current_cred());
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index dd2b35f78b09..08dd94df1a66 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -42,14 +42,14 @@ static const char *proc_ns_get_link(struct dentry *dentry,
 	const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
 	struct task_struct *task;
 	struct path ns_path;
-	void *error = ERR_PTR(-EACCES);
+	int error = -EACCES;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
 
 	task = get_proc_task(inode);
 	if (!task)
-		return error;
+		return ERR_PTR(-EACCES);
 
 	if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
 		error = ns_get_path(&ns_path, task, ns_ops);
@@ -57,7 +57,7 @@ static const char *proc_ns_get_link(struct dentry *dentry,
 			nd_jump_link(&ns_path);
 	}
 	put_task_struct(task);
-	return error;
+	return ERR_PTR(error);
 }
 
 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index d31cb6215905..aed366b4795c 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -76,10 +76,10 @@ static inline int ns_alloc_inum(struct ns_common *ns)
 
 extern struct file *proc_ns_fget(int fd);
 #define get_proc_ns(inode) ((struct ns_common *)(inode)->i_private)
-extern void *ns_get_path(struct path *path, struct task_struct *task,
+extern int ns_get_path(struct path *path, struct task_struct *task,
 			const struct proc_ns_operations *ns_ops);
 typedef struct ns_common *ns_get_path_helper_t(void *);
-extern void *ns_get_path_cb(struct path *path, ns_get_path_helper_t ns_get_cb,
+extern int ns_get_path_cb(struct path *path, ns_get_path_helper_t ns_get_cb,
 			    void *private_data);
 
 extern int ns_get_name(char *buf, size_t size, struct task_struct *task,
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index ba635209ae9a..a2253a044f90 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -302,14 +302,14 @@ int bpf_prog_offload_info_fill(struct bpf_prog_info *info,
 	struct inode *ns_inode;
 	struct path ns_path;
 	char __user *uinsns;
-	void *res;
+	int res;
 	u32 ulen;
 
 	res = ns_get_path_cb(&ns_path, bpf_prog_offload_info_fill_ns, &args);
-	if (IS_ERR(res)) {
+	if (res) {
 		if (!info->ifindex)
 			return -ENODEV;
-		return PTR_ERR(res);
+		return res;
 	}
 
 	down_read(&bpf_devs_lock);
@@ -526,13 +526,13 @@ int bpf_map_offload_info_fill(struct bpf_map_info *info, struct bpf_map *map)
 	};
 	struct inode *ns_inode;
 	struct path ns_path;
-	void *res;
+	int res;
 
 	res = ns_get_path_cb(&ns_path, bpf_map_offload_info_fill_ns, &args);
-	if (IS_ERR(res)) {
+	if (res) {
 		if (!info->ifindex)
 			return -ENODEV;
-		return PTR_ERR(res);
+		return res;
 	}
 
 	ns_inode = ns_path.dentry->d_inode;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 00a014670ed0..3772a04ca802 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7258,7 +7258,7 @@ static void perf_fill_ns_link_info(struct perf_ns_link_info *ns_link_info,
 {
 	struct path ns_path;
 	struct inode *ns_inode;
-	void *error;
+	int error;
 
 	error = ns_get_path(&ns_path, task, ns_ops);
 	if (!error) {
-- 
2.24.0