Re: [PATCH] tools/libs/store: add missing USE_PTHREAD to target .o

[Andrei Stan <andreistan2003@xxxxxxxxx>]

On Fri, Jul 5, 2024 at 6:22 PM Jürgen Groß <jgross@xxxxxxxx> wrote:
>
> On 05.07.24 16:59, Andrei Stan wrote:
> > Currently only shared libraries build with USE_PTHREAD enabled.
> >
> > This patch adds the macro also to xs.o.
> >
> > Backport: 4.18+ # maybe older
> > Signed-off-by: Andrei Stan <andreistan2003@xxxxxxxxx>
>
> Commit dde3e02b7068 did that explicitly, stating that phtreads are
> not compatible with static linking.
>
> Was that reasoning wrong?
>
> Juergen
> ---
> > ---
> >   tools/libs/store/Makefile | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/tools/libs/store/Makefile b/tools/libs/store/Makefile
> > index 0649cf8307..c6f147c72f 100644
> > --- a/tools/libs/store/Makefile
> > +++ b/tools/libs/store/Makefile
> > @@ -20,6 +20,7 @@ CFLAGS += -include $(XEN_ROOT)/tools/config.h
> >   CFLAGS += $(CFLAGS_libxentoolcore)
> >
> >   xs.opic: CFLAGS += -DUSE_PTHREAD
> > +xs.o: CFLAGS += -DUSE_PTHREAD
> >   ifeq ($(CONFIG_Linux),y)
> >   xs.opic: CFLAGS += -DUSE_DLSYM
> >   endif

It was a pretty nasty situation, giving some context, this is for a Go based CLI
tool and some things in there are multithreaded, but i don't think
calling in the
bindings happens anywhere in parallel. Without this patch there would be
some sort of race conditions (or so I assume from the debugging i've done)
happening withing the xen/tools code, making it impossible to start a domain.

In this case there were no issues in linking pthreads statically. I was not even
aware of that being a possible issue. Is it really?

Also I am not too sure how much that code path is actually tested, probably the
majority of the testing is done with dynamic builds.

Andrei