Re: [Xen-devel] [PATCH] tools/xenstore: try to get minimum thread stack size for watch thread

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Feb 22, 2018 at 07:44:22PM +0100, Juergen Gross wrote:
> On 22/02/18 18:28, Wei Liu wrote:
> > On Thu, Feb 22, 2018 at 02:53:35PM +0100, Juergen Gross wrote:
> >> When creating a pthread in xs_watch() try to get the minimal needed
> >> size of the thread from glibc instead of using a constant. This avoids
> >> problems when the library is used in programs with large per-thread
> >> memory.
> >>
> >> Use dlsym() to get the pointer to __pthread_get_minstack() in order to
> >> avoid linkage problems and fall back to the current constant size if
> >> not found.
> >>
> >> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> >> ---
> >> Only compile tested. Jim, can you please verify this patch is solving
> >> your original problem?
> >> ---
> >>  tools/xenstore/Makefile |  4 ++++
> >>  tools/xenstore/xs.c     | 19 ++++++++++++++++++-
> >>  2 files changed, 22 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/tools/xenstore/Makefile b/tools/xenstore/Makefile
> >> index 2b99d2bc1b..fb6c73e297 100644
> >> --- a/tools/xenstore/Makefile
> >> +++ b/tools/xenstore/Makefile
> >> @@ -100,6 +100,10 @@ libxenstore.so.$(MAJOR): 
> >> libxenstore.so.$(MAJOR).$(MINOR)
> >>    ln -sf $< $@
> >>  
> >>  xs.opic: CFLAGS += -DUSE_PTHREAD
> >> +ifeq ($(CONFIG_Linux),y)
> >> +xs.opic: CFLAGS += -DUSE_DLSYM
> >> +xs.opic: LDFLAGS += -ldl
> >> +endif
> >>  
> >>  libxenstore.so.$(MAJOR).$(MINOR): xs.opic xs_lib.opic
> >>    $(CC) $(LDFLAGS) $(PTHREAD_LDFLAGS) -Wl,$(SONAME_LDFLAG) 
> >> -Wl,libxenstore.so.$(MAJOR) $(SHLIB_LDFLAGS) -o $@ $^ 
> >> $(LDLIBS_libxentoolcore) $(SOCKET_LIBS) $(PTHREAD_LIBS) $(APPEND_LDFLAGS)
> >> diff --git a/tools/xenstore/xs.c b/tools/xenstore/xs.c
> >> index abffd9cd80..8372f5b1a4 100644
> >> --- a/tools/xenstore/xs.c
> >> +++ b/tools/xenstore/xs.c
> >> @@ -47,6 +47,11 @@ struct xs_stored_msg {
> >>  
> >>  #include <pthread.h>
> >>  
> >> +#ifdef USE_DLSYM
> >> +#define __USE_GNU
> > 
> > Where does this come from? DLSYM(3) says _GNU_SOURCE (which we already
> > have).
> 
> On my machine build failed, so I looked into the header...
> 

Does putting _GNU_SOURCE at the beginning of that file before all
headers solve the issue? I don't think we want to use an internal
definition.

Wei.

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