From: Markus Wichmann <nullplan@gmx.net>
To: musl@lists.openwall.com
Subject: Re: [musl] Question about calloc, free in CPU_ALLOC and CPU_FREE
Date: Wed, 29 Jun 2022 18:11:36 +0200 [thread overview]
Message-ID: <20220629161136.GD2408@voyager> (raw)
In-Reply-To: <CAA-vtUxnzh-OwpGaZd=D=i_KbYWRu-AWn6uJhQa5RGKg-dxd7g@mail.gmail.com>
On Wed, Jun 29, 2022 at 05:49:55PM +0200, Thomas Stüfe wrote:
> Greetings,
>
> I have a small question about the way muslc implements the CPU_ALLOC and
> CPU_FREE macros.
>
> I see them defined in sched.h as:
>
> #define CPU_ALLOC(n) ((cpu_set_t *)calloc(1,CPU_ALLOC_SIZE(n)))
> #define CPU_FREE(set) free(set)
>
> whereas the glibc defines them as calls to functions __sched_cpu_alloc()
> and __sched_cpufree():
>
> #define __CPU_ALLOC(count) __sched_cpualloc (count)
> #define __CPU_FREE(cpuset) __sched_cpufree (cpuset)
>
> in the end both variants allocate from C-heap, but the muslc variant gets
> inlined directly into the calling code. If that calling code has a function
> "free" or "calloc" (okay, less likely) these get called instead. Could also
> be a class local method in C++.
>
That would be invalid. calloc() and free() are names defined in the C
standard, so no user defined macro or function can have those names.
I don't know about you point about C++, though. Could be conceivably
worked around by using the :: operator, but that is only valid in C++,
so we'd have to #ifdef it.
> I realize this is not a big issue. But would it not be safer to do as the
> glibc does in this case?
>
Not really; if someone wants to use reserved names, there is little
reason to presume that "calloc" is any safer than "__sched_cpualloc".
> Thank you,
>
> Thomas
Ciao,
Markus
next prev parent reply other threads:[~2022-06-29 16:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-29 15:49 Thomas Stüfe
2022-06-29 16:11 ` Markus Wichmann [this message]
2022-06-29 16:32 ` Thomas Stüfe
2022-06-29 16:15 ` Florian Weimer
2022-06-29 16:30 ` Thomas Stüfe
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=20220629161136.GD2408@voyager \
--to=nullplan@gmx.net \
--cc=musl@lists.openwall.com \
/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).