Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   "Eric W. Biederman" <ebiederm@xmission.com>
To:     linux-kernel@vger.kernel.org
Cc:     linux-fsdevel@vger.kernel.org, criu@openvz.org,
        bpf@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Jann Horn <jann@thejh.net>, Kees Cook <keescook@chromium.org>,
        =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= <berrange@redhat.com>,
        Jeff Layton <jlayton@redhat.com>,
        Miklos Szeredi <miklos@szeredi.hu>,
        Matthew Wilcox <willy@infradead.org>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        Chris Wright <chrisw@redhat.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>
Date:   Fri, 20 Nov 2020 17:14:30 -0600
Message-Id: <20201120231441.29911-13-ebiederm@xmission.com>
In-Reply-To: <87r1on1v62.fsf@x220.int.ebiederm.org>
References: <87r1on1v62.fsf@x220.int.ebiederm.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Subject: [PATCH v2 13/24] kcmp: In get_file_raw_ptr use task_lookup_fd_rcu
Precedence: bulk

Modify get_file_raw_ptr to use task_lookup_fd_rcu.  The helper
task_lookup_fd_rcu does the work of taking the task lock and verifying
that task->files != NULL and then calls files_lookup_fd_rcu.  So let
use the helper to make a simpler implementation of get_file_raw_ptr.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 kernel/kcmp.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/kernel/kcmp.c b/kernel/kcmp.c
index 990717c1aed3..36e58eb5a11d 100644
--- a/kernel/kcmp.c
+++ b/kernel/kcmp.c
@@ -61,16 +61,11 @@ static int kcmp_ptr(void *v1, void *v2, enum kcmp_type type)
 static struct file *
 get_file_raw_ptr(struct task_struct *task, unsigned int idx)
 {
-	struct file *file = NULL;
+	struct file *file;
 
-	task_lock(task);
 	rcu_read_lock();
-
-	if (task->files)
-		file = files_lookup_fd_rcu(task->files, idx);
-
+	file = task_lookup_fd_rcu(task, idx);
 	rcu_read_unlock();
-	task_unlock(task);
 
 	return file;
 }
-- 
2.25.0