From: Alexander Monakov <amonakov@ispras.ru>
To: musl@lists.openwall.com
Subject: Re: [PATCH] add pthread_setname_np
Date: Fri, 16 Sep 2016 12:03:16 +0300 (MSK) [thread overview]
Message-ID: <alpine.LNX.2.20.13.1609161117360.30232@monopod.intra.ispras.ru> (raw)
In-Reply-To: <20160916002351.GA5913@nyan>
Hi,
On Thu, 15 Sep 2016, Felix Janda wrote:
> --- /dev/null
> +++ b/src/thread/pthread_setname_np.c
> @@ -0,0 +1,25 @@
> +#include <fcntl.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/prctl.h>
> +
> +#include "pthread_impl.h"
This should bring in the declaration of pthread_setname_np from pthread.h by
#defin'ing _GNU_SOURCE prior to inclusion.
(today, this rule is not enforced with warnings and thus not always followed in
musl, for example the recent pthread_tryjoin_np patch missed that as well)
> +int pthread_setname_np(pthread_t thread, const char *name)
> +{
> + int fd, cs, status = 0;
> + char f[sizeof "/proc/self/task//comm" + 3*sizeof(int)];
> + size_t len;
> +
> + if ((len = strnlen(name, 16)) > 15) return ERANGE;
> +
> + if (thread == pthread_self())
This likely should use the static inline function __pthread_self()?
> + return prctl(PR_SET_NAME, (unsigned long)name, 0, 0, 0) ? errno : 0;
First, prctl is declared as a variadic function, so zeros should be passed with
the right type (0ul); passing fewer than 5 arguments will cause musl's
implementation of prctl to invoke UB, since it always retrieves 4 variadic arguments.
Second, while I don't have a strong opinion on whether musl wants to use prctl
here (my previous comment in this thread was based on the wrong idea that prctl
would be sufficient in all cases - sorry about that), I think some tuning would
be nice in case the decision is to use prctl. So, either
return -__syscall(SYS_prctl, PR_SET_NAME, name);
(not sure if Rich would like it), or
if (thread == pthread_self()) {
status = prctl(...);
} else {
...
fd = status = open(f, O_WRONLY);
if (fd >= 0) {
status = write(fd, name, len);
close(fd);
}
pthread_setcancelstate(cs, 0);
}
return status ? errno : 0;
> + snprintf(f, sizeof f, "/proc/self/task/%d/comm", thread->tid);
> + pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
> + if ((fd = open(f, O_WRONLY)) < 0 || write(fd, name, len) < 0) status = errno;
> + if (fd >= 0) close(fd);
> + pthread_setcancelstate(cs, 0);
> + return status;
> +}
Thanks.
Alexander
next prev parent reply other threads:[~2016-09-16 9:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-16 0:23 Felix Janda
2016-09-16 9:03 ` Alexander Monakov [this message]
2016-09-16 9:09 ` Alexander Monakov
2016-09-16 15:00 ` Rich Felker
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=alpine.LNX.2.20.13.1609161117360.30232@monopod.intra.ispras.ru \
--to=amonakov@ispras.ru \
--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).