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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 14/36] fs: add ksys_mount() helper; remove in-kernel calls to sys_mount()
Date: Fri, 16 Mar 2018 09:58:46 -0700	[thread overview]
Message-ID: <CA+55aFyGtWEZFzUKJO5NZNxeh4Z624P0EOy6u-zisJT354eLeQ@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a2H=LoW5apWNxbqda+JAa33R=tqc7RK=2Uv7J_Xpy+bgg@mail.gmail.com>

On Thu, Mar 15, 2018 at 1:11 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>
> Shouldn't the callers of sys_mount just call do_mount() instead?

So for most of these, I'd rather not really change the code and just
do a direct translation, but I have to agree that "sys_mount ->
do_mount" might be special.

As you say, the only thing sys_mount() does is to copy things from
user space and allocate temporaries, and then call do_mount(). And we
already use do_mount in other places.

So it translating sys_mount() to do_mount() might just be the right thing to do.

Of course, do_mount() still ends up doing yet more "translate user
mode stuff to kernel stuff", so it's kind o fa confusing half-way
state where the user mountpoint name is still in user space, and the
flags are still in the MS namespace, but the device name and the mount
options have been moved to kernel space.

So I dunno. It might make sense to convert to do_mount(), but in many
ways ksys_mount() that just passes *everything* as if it was a user
call is actually more logical, even if it's just pointless churn to
then copy things.

I do like the mindless "let's just use the SYSCALL_DEFINEx()
interfaces for in-kernel use" model, exactly because it's so
black-and-white and doesn't have these kinds of "on one hand.."
issues.

                   Linus

  parent reply	other threads:[~2018-03-16 16:58 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-15 19:04 [PATCH v2 00/36] remove in-kernel syscall invocations (part 1) Dominik Brodowski
2018-03-15 19:04 ` [PATCH v2 01/36] syscalls: define goal to not call sys_xyzzy() from within the kernel Dominik Brodowski
2018-03-15 19:04 ` [PATCH v2 02/36] kernel: use kernel_wait4() instead of sys_wait4() Dominik Brodowski
2018-03-16 16:58   ` Luis R. Rodriguez
2018-03-17 16:44     ` Dominik Brodowski
2018-03-15 19:04 ` [PATCH v2 03/36] mm: use do_futex() instead of sys_futex() in mm_release() Dominik Brodowski
2018-03-16 11:58   ` Thomas Gleixner
2018-03-16 18:43   ` Darren Hart
2018-03-16 19:03     ` Andy Lutomirski
2018-03-16 21:44       ` Darren Hart
2018-03-17 16:39         ` Dominik Brodowski
2018-03-15 19:04 ` [PATCH v2 04/36] kernel: add do_getpgid() helper; remove internal call to sys_getpgid() Dominik Brodowski
2018-03-15 19:04 ` [PATCH v2 05/36] fs: add do_readlinkat() helper; remove internal call to sys_readlinkat() Dominik Brodowski
2018-03-15 19:04 ` [PATCH v2 06/36] fs: add do_pipe2() helper; remove internal call to sys_pipe2() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 07/36] fs: add do_renameat2() helper; remove internal call to sys_renameat2() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 08/36] fs: add do_futimesat() helper; remove internal call to sys_futimesat() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 09/36] syscalls: add do_epoll_*() helpers; remove internal calls to sys_epoll_*() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 10/36] fs: add do_signalfd4() helper; remove internal calls to sys_signalfd4() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 11/36] fs: add do_eventfd() helper; remove internal call to sys_eventfd() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 12/36] kernel: open-code sys_rt_sigpending() in sys_sigpending() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 13/36] x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to sys_ioperm() Dominik Brodowski
2018-03-16  8:43   ` Christoph Hellwig
2018-03-16 11:13     ` Dominik Brodowski
2018-03-16 12:00   ` Thomas Gleixner
2018-03-16 14:45     ` Dominik Brodowski
2018-03-16 14:47       ` Thomas Gleixner
2018-03-15 19:05 ` [PATCH v2 14/36] fs: add ksys_mount() helper; remove in-kernel calls to sys_mount() Dominik Brodowski
2018-03-15 20:11   ` Arnd Bergmann
2018-03-16  8:46     ` Christoph Hellwig
2018-03-16 16:58     ` Linus Torvalds [this message]
2018-03-17 16:52     ` Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 15/36] fs: add ksys_umount() helper; remove in-kernel call to sys_umount() Dominik Brodowski
2018-03-16  8:47   ` Christoph Hellwig
2018-03-17 16:58     ` Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 16/36] fs: add ksys_dup{,3}() helper; remove in-kernel calls to sys_dup{,3}() Dominik Brodowski
2018-03-16  8:48   ` Christoph Hellwig
2018-03-17 17:01     ` Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 17/36] fs: add ksys_chroot() helper; remove-in kernel calls to sys_chroot() Dominik Brodowski
2018-03-15 20:44   ` Arnd Bergmann
2018-03-16  8:49     ` Christoph Hellwig
2018-03-17 17:04     ` Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 18/36] fs: add ksys_write() helper; remove in-kernel calls to sys_write() Dominik Brodowski
2018-03-16  8:52   ` Christoph Hellwig
2018-03-17 17:06     ` Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 19/36] kernel: add ksys_unshare() helper; remove in-kernel calls to sys_unshare() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 20/36] mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 21/36] mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to sys_mmap_pgoff() Dominik Brodowski
2018-03-15 20:54   ` Arnd Bergmann
2018-03-15 19:05 ` [PATCH v2 22/36] fs: add ksys_chdir() helper; remove in-kernel calls to sys_chdir() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 23/36] fs: add ksys_sync_file_range helper(); remove in-kernel calls to syscall Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 24/36] fs: add ksys_unlink() wrapper; remove in-kernel calls to sys_unlink() Dominik Brodowski
2018-03-15 20:21   ` Arnd Bergmann
2018-03-17 17:09     ` Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 25/36] hostfs: rename do_rmdir() to hostfs_do_rmdir() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 26/36] fs: add ksys_rmdir() wrapper; remove in-kernel calls to sys_rmdir() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 27/36] fs: add do_mkdirat() helper and ksys_mkdir() wrapper; remove in-kernel calls to syscall Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 28/36] fs: add do_symlinkat() helper and ksys_symlink() " Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 29/36] fs: add do_mknodat() helper and ksys_mknod() " Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 30/36] fs: add do_linkat() helper and ksys_link() " Dominik Brodowski
2018-03-15 20:30   ` Arnd Bergmann
2018-03-17 17:11     ` Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 31/36] fs: add ksys_fchmod() and do_fchmodat() helpers and ksys_chmod() " Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 32/36] fs: add do_faccessat() helper and ksys_access() " Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 33/36] fs: add ksys_ftruncate() wrapper; remove in-kernel calls to sys_ftruncate() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 34/36] fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 35/36] fs: add ksys_close() wrapper; remove in-kernel calls to sys_close() Dominik Brodowski
2018-03-15 19:05 ` [PATCH v2 36/36] fs: add ksys_open() wrapper; remove in-kernel calls to sys_open() Dominik Brodowski
2018-03-15 21:02 ` [PATCH v2 00/36] remove in-kernel syscall invocations (part 1) Arnd Bergmann
2018-03-16  0:38   ` Andy Lutomirski
2018-03-16  0:54     ` Linus Torvalds
2018-03-16  8:54       ` Christoph Hellwig
2018-03-16 14:20         ` Al Viro
2018-03-16 16:47           ` Linus Torvalds
2018-03-17 17:13   ` Dominik Brodowski
2018-03-16  9:01 ` Zhang, Ning A
2018-03-16 10:25   ` Dominik Brodowski

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