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 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).

Wei.

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