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From:   ebiederm@xmission.com (Eric W. Biederman)
To:     Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc:     Christian Brauner <christian.brauner@ubuntu.com>,
        Kees Cook <keescook@chromium.org>,
        Jann Horn <jannh@google.com>, Jonathan Corbet <corbet@lwn.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Andrei Vagin <avagin@gmail.com>,
        Ingo Molnar <mingo@kernel.org>,
        "Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
        Yuyang Du <duyuyang@gmail.com>,
        David Hildenbrand <david@redhat.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        David Howells <dhowells@redhat.com>,
        James Morris <jamorris@linux.microsoft.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Shakeel Butt <shakeelb@google.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Christian Kellner <christian@kellner.me>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        "Dmitry V. Levin" <ldv@altlinux.org>,
        "linux-doc\@vger.kernel.org" <linux-doc@vger.kernel.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-fsdevel\@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "linux-mm\@kvack.org" <linux-mm@kvack.org>,
        "stable\@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-api\@vger.kernel.org" <linux-api@vger.kernel.org>
References: <AM6PR03MB5170EB4427BF5C67EE98FF09E4E60@AM6PR03MB5170.eurprd03.prod.outlook.com>
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        <87v9nmjulm.fsf@x220.int.ebiederm.org>
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        <202003021531.C77EF10@keescook>
        <20200303085802.eqn6jbhwxtmz4j2x@wittgenstein>
        <AM6PR03MB5170285B336790D3450E2644E4E40@AM6PR03MB5170.eurprd03.prod.outlook.com>
        <87v9nlii0b.fsf@x220.int.ebiederm.org>
        <AM6PR03MB5170609D44967E044FD1BE40E4E40@AM6PR03MB5170.eurprd03.prod.outlook.com>
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        <87r1y8dqqz.fsf@x220.int.ebiederm.org>
        <AM6PR03MB517053AED7DC89F7C0704B7DE4E50@AM6PR03MB5170.eurprd03.prod.outlook.com>
        <AM6PR03MB51703B44170EAB4626C9B2CAE4E20@AM6PR03MB5170.eurprd03.prod.outlook.com>
        <87tv32cxmf.fsf_-_@x220.int.ebiederm.org>
        <87v9ne5y4y.fsf_-_@x220.int.ebiederm.org>
Date:   Sun, 08 Mar 2020 16:35:26 -0500
In-Reply-To: <87v9ne5y4y.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's
        message of "Sun, 08 Mar 2020 16:34:37 -0500")
Message-ID: <87pndm5y3l.fsf_-_@x220.int.ebiederm.org>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
Subject: [PATCH v2 1/5] exec: Only compute current once in flush_old_exec
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


Make it clear that current only needs to be computed once in
flush_old_exec.  This may have some efficiency improvements and it
makes the code easier to change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/exec.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index db17be51b112..c3f34791f2f0 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1260,13 +1260,14 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
  */
 int flush_old_exec(struct linux_binprm * bprm)
 {
+	struct task_struct *me = current;
 	int retval;
 
 	/*
 	 * Make sure we have a private signal table and that
 	 * we are unassociated from the previous thread group.
 	 */
-	retval = de_thread(current);
+	retval = de_thread(me);
 	if (retval)
 		goto out;
 
@@ -1294,10 +1295,10 @@ int flush_old_exec(struct linux_binprm * bprm)
 	bprm->mm = NULL;
 
 	set_fs(USER_DS);
-	current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
+	me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
 					PF_NOFREEZE | PF_NO_SETAFFINITY);
 	flush_thread();
-	current->personality &= ~bprm->per_clear;
+	me->personality &= ~bprm->per_clear;
 
 	/*
 	 * We have to apply CLOEXEC before we change whether the process is
@@ -1305,7 +1306,7 @@ int flush_old_exec(struct linux_binprm * bprm)
 	 * trying to access the should-be-closed file descriptors of a process
 	 * undergoing exec(2).
 	 */
-	do_close_on_exec(current->files);
+	do_close_on_exec(me->files);
 	return 0;
 
 out:
-- 
2.25.0