From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f171.google.com (mail-lb0-f171.google.com [209.85.217.171]) by kanga.kvack.org (Postfix) with ESMTP id 36C476B0037 for ; Thu, 24 Jul 2014 12:50:57 -0400 (EDT) Received: by mail-lb0-f171.google.com with SMTP id l4so2524737lbv.30 for ; Thu, 24 Jul 2014 09:50:56 -0700 (PDT) Received: from mail-la0-x230.google.com (mail-la0-x230.google.com [2a00:1450:4010:c03::230]) by mx.google.com with ESMTPS id zt5si27591569lbb.48.2014.07.24.09.50.54 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 24 Jul 2014 09:50:54 -0700 (PDT) Received: by mail-la0-f48.google.com with SMTP id gl10so2107183lab.7 for ; Thu, 24 Jul 2014 09:50:54 -0700 (PDT) Message-Id: <20140724165047.597307734@openvz.org> Date: Thu, 24 Jul 2014 20:47:00 +0400 From: Cyrill Gorcunov Subject: [rfc 3/4] prctl: PR_SET_MM -- Factor out mmap_sem when update mm::exe_file References: <20140724164657.452106845@openvz.org> Content-Disposition: inline; filename=prctl-rework-prctl_set_mm_exe_file-locked Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: gorcunov@openvz.org, keescook@chromium.org, tj@kernel.org, akpm@linux-foundation.org, avagin@openvz.org, ebiederm@xmission.com, hpa@zytor.com, serge.hallyn@canonical.com, xemul@parallels.com, segoon@openwall.com, kamezawa.hiroyu@jp.fujitsu.com, mtk.manpages@gmail.com, jln@google.com Instead of taking mm->mmap_sem inside prctl_set_mm_exe_file move it out of and rename the helper to prctl_set_mm_exe_file_locked. This will allow to reuse this function in a next patch. Signed-off-by: Cyrill Gorcunov Cc: Kees Cook Cc: Tejun Heo Cc: Andrew Morton Cc: Andrew Vagin Cc: Eric W. Biederman Cc: H. Peter Anvin Cc: Serge Hallyn Cc: Pavel Emelyanov Cc: Vasiliy Kulikov Cc: KAMEZAWA Hiroyuki Cc: Michael Kerrisk Cc: Julien Tinnes --- kernel/sys.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) Index: linux-2.6.git/kernel/sys.c =================================================================== --- linux-2.6.git.orig/kernel/sys.c +++ linux-2.6.git/kernel/sys.c @@ -1628,12 +1628,14 @@ SYSCALL_DEFINE1(umask, int, mask) return mask; } -static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd) +static int prctl_set_mm_exe_file_locked(struct mm_struct *mm, unsigned int fd) { struct fd exe; struct inode *inode; int err; + VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); + exe = fdget(fd); if (!exe.file) return -EBADF; @@ -1654,8 +1656,6 @@ static int prctl_set_mm_exe_file(struct if (err) goto exit; - down_write(&mm->mmap_sem); - /* * Forbid mm->exe_file change if old file still mapped. */ @@ -1667,7 +1667,7 @@ static int prctl_set_mm_exe_file(struct if (vma->vm_file && path_equal(&vma->vm_file->f_path, &mm->exe_file->f_path)) - goto exit_unlock; + goto exit; } /* @@ -1678,13 +1678,10 @@ static int prctl_set_mm_exe_file(struct */ err = -EPERM; if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags)) - goto exit_unlock; + goto exit; err = 0; set_mm_exe_file(mm, exe.file); /* this grabs a reference to exe.file */ -exit_unlock: - up_write(&mm->mmap_sem); - exit: fdput(exe); return err; @@ -1704,8 +1701,12 @@ static int prctl_set_mm(int opt, unsigne if (!capable(CAP_SYS_RESOURCE)) return -EPERM; - if (opt == PR_SET_MM_EXE_FILE) - return prctl_set_mm_exe_file(mm, (unsigned int)addr); + if (opt == PR_SET_MM_EXE_FILE) { + down_write(&mm->mmap_sem); + error = prctl_set_mm_exe_file_locked(mm, (unsigned int)addr); + up_write(&mm->mmap_sem); + return error; + } if (addr >= TASK_SIZE || addr < mmap_min_addr) return -EINVAL; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org