linux-kernel - [PATCH 10/10] teach proc_self_get_link()/proc_thread_self_get

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Message-Id: <1447801246-24588-10-git-send-email-viro@ZenIV.linux.org.uk>
Date:	Tue, 17 Nov 2015 23:00:46 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	linux-kernel@...r.kernel.org
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Neil Brown <neilb@...e.de>, linux-fsdevel@...r.kernel.org
Subject: [PATCH 10/10] teach proc_self_get_link()/proc_thread_self_get_link() to work in RCU mode

From: Al Viro <viro@...iv.linux.org.uk>

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/proc/self.c        | 8 +++-----
 fs/proc/thread_self.c | 9 ++++-----
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/fs/proc/self.c b/fs/proc/self.c
index 9dd0ae6..7a8b19e 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -25,14 +25,12 @@ static const char *proc_self_get_link(struct dentry *dentry,
 	pid_t tgid = task_tgid_nr_ns(current, ns);
 	char *name;
 
-	if (!dentry)
-		return ERR_PTR(-ECHILD);
 	if (!tgid)
 		return ERR_PTR(-ENOENT);
 	/* 11 for max length of signed int in decimal + NULL term */
-	name = kmalloc(12, GFP_KERNEL);
-	if (!name)
-		return ERR_PTR(-ENOMEM);
+	name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC);
+	if (unlikely(!name))
+		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
 	sprintf(name, "%d", tgid);
 	return *cookie = name;
 }
diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index 50eef6f..03eaa84 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -27,13 +27,12 @@ static const char *proc_thread_self_get_link(struct dentry *dentry,
 	pid_t pid = task_pid_nr_ns(current, ns);
 	char *name;
 
-	if (!dentry)
-		return ERR_PTR(-ECHILD);
 	if (!pid)
 		return ERR_PTR(-ENOENT);
-	name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, GFP_KERNEL);
-	if (!name)
-		return ERR_PTR(-ENOMEM);
+	name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF,
+				dentry ? GFP_KERNEL : GFP_ATOMIC);
+	if (unlikely(!name))
+		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
 	sprintf(name, "%d/task/%d", tgid, pid);
 	return *cookie = name;
 }
-- 
2.1.4

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