From: Christian Brauner <brauner@kernel.org>
To: 王洪亮 <wanghongliang@loongson.cn>
Cc: musl@lists.openwall.com
Subject: Re: [musl] Re: add loongarch64 port
Date: Wed, 20 Apr 2022 15:33:25 +0200 [thread overview]
Message-ID: <20220420133325.pdppfuc3ijggrgc4@wittgenstein> (raw)
In-Reply-To: <de1a78a0-ea99-abef-8046-0cc8297b9861@loongson.cn>
On Wed, Apr 20, 2022 at 05:09:08PM +0800, 王洪亮 wrote:
>
> 在 2022/4/14 下午5:36, Christian Brauner 写道:
> > On Wed, Apr 13, 2022 at 10:09:31AM -0400, Rich Felker wrote:
> > > On Wed, Apr 13, 2022 at 03:25:05PM +0200, Arnd Bergmann wrote:
> > > > On Wed, Apr 13, 2022 at 11:04 AM Christian Brauner <brauner@kernel.org> wrote:
> > > > > On Wed, Apr 13, 2022 at 10:26:06AM +0200, Arnd Bergmann wrote:
> > > > > > The normal rule is that we don't define obsolete system calls in new
> > > > > > architectures when an improved variant has been added, e.g. oldoldstat,
> > > > > > oldstat, stat, newstat and stat64 have all been replaced by statx over
> > > > > > the decades. I was expecting the same to be true for clone(), but if
> > > > > > clone3() is not meant as a replacement, we can keep both around.
> > > > > No, I agree with you on this and would like to only implement clone3()
> > > > > on new architectures.
> > > > >
> > > > > What I'm asking is whether removing the size == 0 check is enough to
> > > > > unblock the missing behavior and whether you'd be on board with removing
> > > > > the check?
> > > > I think that's ok here, since we'd only rely on this for loongarch64 at the
> > > > moment. It would probably need to be documented in the man page
> > > > as a special case though.
> > > I'm okay with removing the check for size==0 (so size==0 will be
> > > allowed) and dropping __NR_clone on new archs, as long as it's noted
> > > in comments/documentation that size==0 is explicitly allowed so nobody
> > > breaks this in the future.
> > Ok, I'll try to have a patch ready early next week since I'm currently
> > out sick.
>
> Hi,
>
> I'm implementing __NR_clone3 syscall within __clone().
>
> I have another problem:CLONE_DETACHED
>
> in musl,internal call __clone()(such as __pthread_create()),the input
> parameter flags
>
> has been set CLONE_DETACHED ,in kernel,there is a check in
> clone3_args_valid(),
>
> if the condition met,return false.
>
> How to deal with this problem?
CLONE_DETACHED is meaningles since Linux on 2.6.2. There really should
be <=2.6.1 living kernel anywhere where CLONE_DETACHED does anything.
I've documented that in detail under [1] as:
CLONE_DETACHED (historical)
For a while (during the Linux 2.5 development series)
there was a CLONE_DETACHED flag, which caused the parent
not to receive a signal when the child terminated.
Ultimately, the effect of this flag was subsumed under the
CLONE_THREAD flag and by the time Linux 2.6.0 was
released, this flag had no effect. Starting in Linux
2.6.2, the need to give this flag together with
CLONE_THREAD disappeared.
This flag is still defined, but it is usually ignored when
calling clone(). However, see the description of
CLONE_PIDFD for some exceptions.
[1]: https://man7.org/linux/man-pages/man2/clone.2.html
Would it be possible to drop this flag from musl's pthread_create()
implementation? (Iirc, glibc dropped CLONE_DETACHED in 2004.)
>
> src/thread/pthread_create.c:
> int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict
> attrp,
> void *(*entry)(void *), void *restrict arg)
> {
> unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
> | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
> | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
> ...
> ret = __clone((c11 ? start_c11 : start), stack, flags, args, &new->tid,
> TP_ADJ(new), &__thread_list_lock);
> }
>
> kernel/fork.c:
> static bool clone3_args_valid(struct kernel_clone_args *kargs)
> {
> /*
> * - make the CLONE_DETACHED bit reusable for clone3
> * - make the CSIGNAL bits reusable for clone3
> */
> if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
> return false;
> }
>
>
> Hongliang Wang
>
next prev parent reply other threads:[~2022-04-20 13:33 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-31 6:20 王洪亮
2022-03-31 8:14 ` Arnd Bergmann
2022-04-01 7:40 ` 王洪亮
2022-04-01 7:48 ` Arnd Bergmann
2022-04-02 6:19 ` 王洪亮
2022-04-02 7:21 ` Rich Felker
2022-04-02 9:53 ` 王洪亮
2022-04-27 1:58 ` 王洪亮
2022-04-27 2:13 ` Rich Felker
2022-03-31 18:47 ` Rich Felker
2022-04-02 7:59 ` 王洪亮
2022-04-06 2:08 ` 王洪亮
2022-04-06 16:00 ` Markus Wichmann
2022-04-08 2:21 ` 王洪亮
2022-04-08 6:46 ` Arnd Bergmann
2022-04-09 3:54 ` 王洪亮
2022-04-09 11:06 ` Arnd Bergmann
2022-04-09 13:19 ` Rich Felker
2022-04-09 13:30 ` Rich Felker
2022-04-10 10:30 ` Arnd Bergmann
2022-04-10 15:26 ` Rich Felker
2022-04-11 8:03 ` Arnd Bergmann
2022-04-11 12:11 ` Rich Felker
2022-04-11 13:01 ` Arnd Bergmann
2022-04-12 1:11 ` 王洪亮
2022-04-13 1:16 ` 王洪亮
2022-04-13 7:26 ` Christian Brauner
2022-04-13 8:26 ` Arnd Bergmann
2022-04-13 9:04 ` Christian Brauner
2022-04-13 13:25 ` Arnd Bergmann
2022-04-13 14:09 ` Rich Felker
2022-04-14 9:36 ` Christian Brauner
2022-04-20 9:09 ` 王洪亮
2022-04-20 13:33 ` Christian Brauner [this message]
2022-04-20 13:54 ` Rich Felker
2022-04-21 6:54 ` 王洪亮
2022-04-14 9:36 ` Christian Brauner
2022-04-13 7:19 ` Christian Brauner
2022-04-13 14:06 ` Rich Felker
2022-04-11 3:40 ` 王洪亮
-- strict thread matches above, loose matches on Subject: below --
2022-03-22 3:52 [musl] " 王洪亮
2022-03-29 8:12 ` [musl] " 王洪亮
2022-03-29 8:26 ` Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220420133325.pdppfuc3ijggrgc4@wittgenstein \
--to=brauner@kernel.org \
--cc=musl@lists.openwall.com \
--cc=wanghongliang@loongson.cn \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).