On Fri, Sep 19, 2025 at 10:39:31AM +0200, Markus Armbruster wrote:
> Daniel P. Berrangé <berra...@redhat.com> writes:
>
> > The ability to set the thread name needs to be used in a number
> > of places, so expose the current impls as public methods.
> >
> > Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
> > Reviewed-by: Dr. David Alan Gilbert <d...@treblig.org>
> > Signed-off-by: Daniel P. Berrangé <berra...@redhat.com>
> > ---
> > include/qemu/thread.h | 1 +
> > util/qemu-thread-posix.c | 30 ++++++++++++++++++------------
> > util/qemu-thread-win32.c | 6 +++---
> > 3 files changed, 22 insertions(+), 15 deletions(-)
> >
> > diff --git a/include/qemu/thread.h b/include/qemu/thread.h
> > index 3a286bb3ef..27b888ab0a 100644
> > --- a/include/qemu/thread.h
> > +++ b/include/qemu/thread.h
> > @@ -215,6 +215,7 @@ void *qemu_thread_join(QemuThread *thread);
> > void qemu_thread_get_self(QemuThread *thread);
> > bool qemu_thread_is_self(QemuThread *thread);
> > G_NORETURN void qemu_thread_exit(void *retval);
> > +void qemu_thread_set_name(const char *name);
> >
> > struct Notifier;
> > /**
> > diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
> > index 7c985b5d38..ddaa1de4dd 100644
> > --- a/util/qemu-thread-posix.c
> > +++ b/util/qemu-thread-posix.c
> > @@ -329,6 +329,21 @@ static void qemu_thread_atexit_notify(void *arg)
> > notifier_list_notify(&thread_exit, NULL);
> > }
> >
> > +void qemu_thread_set_name(const char *name)
> > +{
> > + /*
> > + * Attempt to set the threads name; note that this is for debug, so
> > + * we're not going to fail if we can't set it.
> > + */
> > +# if defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
> > + pthread_setname_np(pthread_self(), name);
> > +# elif defined(CONFIG_PTHREAD_SETNAME_NP_WO_TID)
> > + pthread_setname_np(name);
> > +# elif defined(CONFIG_PTHREAD_SET_NAME_NP)
> > + pthread_set_name_np(pthread_self(), name);
> > +# endif
> > +}
> > +
> > typedef struct {
> > void *(*start_routine)(void *);
> > void *arg;
> > @@ -342,20 +357,11 @@ static void *qemu_thread_start(void *args)
> > void *arg = qemu_thread_args->arg;
> > void *r;
> >
> > - /* Attempt to set the threads name; note that this is for debug, so
> > - * we're not going to fail if we can't set it.
> > - */
> > if (qemu_thread_args->name) {
> > -# if defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
> > - pthread_setname_np(pthread_self(), qemu_thread_args->name);
> > -# elif defined(CONFIG_PTHREAD_SETNAME_NP_WO_TID)
> > - pthread_setname_np(qemu_thread_args->name);
> > -# elif defined(CONFIG_PTHREAD_SET_NAME_NP)
> > - pthread_set_name_np(pthread_self(), qemu_thread_args->name);
> > -# endif
> > + qemu_thread_set_name(qemu_thread_args->name);
>
> Clean factoring out up to here.
>
> > + QEMU_TSAN_ANNOTATE_THREAD_NAME(qemu_thread_args->name);
> > + g_free(qemu_thread_args->name);
> > }
> > - QEMU_TSAN_ANNOTATE_THREAD_NAME(qemu_thread_args->name);
> > - g_free(qemu_thread_args->name);
>
> This part avoids
>
> QEMU_TSAN_ANNOTATE_THREAD_NAME(NULL);
> g_free(NULL);
>
> The latter is an obvious no-op. The former isn't. Separate patch or
> mention in the commit message?
I'll just drop this since it isn't needed by the patch
>
> > g_free(qemu_thread_args);
> >
> > /*
> > diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
> > index 9595a5b090..62eaa11026 100644
> > --- a/util/qemu-thread-win32.c
> > +++ b/util/qemu-thread-win32.c
> > @@ -316,7 +316,7 @@ void *qemu_thread_join(QemuThread *thread)
> > return ret;
> > }
> >
> > -static void set_thread_description(HANDLE h, const char *name)
> > +void qemu_thread_set_name(const char *name)
> > {
> > g_autofree wchar_t *namew = NULL;
> >
> > @@ -329,7 +329,7 @@ static void set_thread_description(HANDLE h, const char
> > *name)
> > return;
> > }
> >
> > - SetThreadDescriptionFunc(h, namew);
> > + SetThreadDescriptionFunc(GetCurrentThread(), namew);
> > }
> >
> > void qemu_thread_create(QemuThread *thread, const char *name,
> > @@ -356,7 +356,7 @@ void qemu_thread_create(QemuThread *thread, const char
> > *name,
> hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
> data, 0, &thread->tid);
> if (!hThread) {
> > error_exit(GetLastError(), __func__);
> > }
> > if (name) {
> > - set_thread_description(hThread, name);
> > + qemu_thread_set_name(name);
> > }
> > CloseHandle(hThread);
>
> This changes the first argument of SetThreadDescriptionFunc() from the
> value of _beginthreadex() to GetCurrentThread(). I'm a happy Windows
> ignoramus... sure these refer to the same thread?
No, I messed up here. I should have moved the qemu_thread_set_name call
into the thread function, as this is still the parent thread.
With regards,
Daniel
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