On 02/26/2018 01:46 AM, 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 <jgr...@suse.com>
---
V2:
- use _GNU_SOURCE (Wei Liu)
- call __pthread_get_minstack() with parameter
- add -ldl to correct make flags
- ensure to not using smaller stack size than today
---
tools/xenstore/Makefile | 4 ++++
tools/xenstore/xs.c | 21 ++++++++++++++++++++-
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/tools/xenstore/Makefile b/tools/xenstore/Makefile
index 2b99d2bc1b..0831be0b6f 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
+libxenstore.so.$(MAJOR).$(MINOR): LDFLAGS += -ldl
+endif
Dropping this patch in one of my automated builds caused a libxenstore link
failure
[ 99s] gcc -lsystemd -ldl -pthread -Wl,-soname -Wl,libxenstore.so.3.0
-shared -o libxenstore.so.3.0.3 xs.opic xs_lib.opic
/home/abuild/rpmbuild/BUILD/xen-4.10.0-testing/tools/xenstore/../../tools/libs/toolcore/libxentoolcore.so
[ 99s]
/home/abuild/rpmbuild/BUILD/xen-4.10.0-testing/tools/xenstore/../../tools/xenstore/libxenstore.so:
undefined reference to `dlsym'
I hacked around it by appending '-ldl' to the end of the subsequent
libxenstore.so rule.
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..77700bff2b 100644
--- a/tools/xenstore/xs.c
+++ b/tools/xenstore/xs.c
@@ -16,6 +16,8 @@
License along with this library; If not, see
<http://www.gnu.org/licenses/>.
*/
+#define _GNU_SOURCE
+
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
@@ -47,6 +49,10 @@ struct xs_stored_msg {
#include <pthread.h>
+#ifdef USE_DLSYM
+#include <dlfcn.h>
+#endif
+
struct xs_handle {
/* Communications channel to xenstore daemon. */
int fd;
@@ -810,12 +816,25 @@ bool xs_watch(struct xs_handle *h, const char *path,
const char *token)
if (!h->read_thr_exists) {
sigset_t set, old_set;
pthread_attr_t attr;
+ static size_t stack_size;
+#ifdef USE_DLSYM
+ size_t (*getsz)(pthread_attr_t *attr);
+#endif
if (pthread_attr_init(&attr) != 0) {
mutex_unlock(&h->request_mutex);
return false;
}
- if (pthread_attr_setstacksize(&attr, READ_THREAD_STACKSIZE) !=
0) {
+ if (!stack_size) {
+#ifdef USE_DLSYM
+ getsz = dlsym(RTLD_DEFAULT, "__pthread_get_minstack");
+ if (getsz)
+ stack_size = getsz(&attr);
+#endif
+ if (stack_size < READ_THREAD_STACKSIZE)
+ stack_size = READ_THREAD_STACKSIZE;
+ }
+ if (pthread_attr_setstacksize(&attr, stack_size) != 0) {
pthread_attr_destroy(&attr);
mutex_unlock(&h->request_mutex);
return false;
This worked fine, even on the system with the buggy glibc.
Tested-by: Jim Fehlig <jfeh...@suse.com>
Regards,
Jim
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