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Message-ID: <20160917023648.GW15995@brightrain.aerifal.cx>
Date: Fri, 16 Sep 2016 22:36:49 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH v2] add pthread_setname_np
On Fri, Sep 16, 2016 at 08:54:00PM -0400, Felix Janda wrote:
> the thread name is displayed by gdb's "info threads".
> ---
> v1->v2: add _GNU_SOURCE, and "UL" to prctl arguments
>
> I hope that there are no programs for which this function is
> performance critical...
>
> Thanks for the review so far!
> ---
> include/pthread.h | 1 +
> src/thread/pthread_setname_np.c | 26 ++++++++++++++++++++++++++
> 2 files changed, 27 insertions(+)
> create mode 100644 src/thread/pthread_setname_np.c
>
> diff --git a/include/pthread.h b/include/pthread.h
> index 3d2e0c4..94ef919 100644
> --- a/include/pthread.h
> +++ b/include/pthread.h
> @@ -214,6 +214,7 @@ struct cpu_set_t;
> int pthread_getaffinity_np(pthread_t, size_t, struct cpu_set_t *);
> int pthread_setaffinity_np(pthread_t, size_t, const struct cpu_set_t *);
> int pthread_getattr_np(pthread_t, pthread_attr_t *);
> +int pthread_setname_np(pthread_t, const char *);
> int pthread_tryjoin_np(pthread_t, void **);
> int pthread_timedjoin_np(pthread_t, void **, const struct timespec *);
> #endif
> diff --git a/src/thread/pthread_setname_np.c b/src/thread/pthread_setname_np.c
> new file mode 100644
> index 0000000..82d35e1
> --- /dev/null
> +++ b/src/thread/pthread_setname_np.c
> @@ -0,0 +1,26 @@
> +#define _GNU_SOURCE
> +#include <fcntl.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/prctl.h>
> +
> +#include "pthread_impl.h"
> +
> +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())
> + return prctl(PR_SET_NAME, (unsigned long)name, 0UL, 0UL, 0UL) ? 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;
> +}
> --
> 2.7.3
I don't see anything left that particularly needs changing. I'll see
if anyone else has comments and commit if not.
I did just notice that my hopes that the function could be implemented
with just public APIs aren't met, since thread->tid is needed. But
this could be fixed in the future if there's ever consensus on a
pthread_gettid_np function.
Rich
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