[Xen-devel] [PATCH 2 of 2 V3] xs: set read_thread stacksize

[Simon Rowe <simon.rowe@xxxxxxxxxxxxx>]

xs_watch() creates a thread to wake watchers using default attributes. The
stacksize can be quite large (8 MB on Linux), applications that link against
xenstore end up having a larger memory footprint than necessary.

Signed-off-by: Simon Rowe <simon.rowe@xxxxxxxxxxxxx>

---
Changed since v1:
  * remove test for _POSIX_THREAD_ATTR_STACKSIZE
  * use define for constant

diff -r 711a707dc776 -r ae3a05009962 tools/xenstore/xs.c
--- a/tools/xenstore/xs.c       Wed Jun 06 10:04:15 2012 +0100
+++ b/tools/xenstore/xs.c       Wed Jun 06 10:06:44 2012 +0100
@@ -702,21 +702,36 @@ bool xs_watch(struct xs_handle *h, const
        struct iovec iov[2];
 
 #ifdef USE_PTHREAD
+#define READ_THREAD_STACKSIZE (16 * 1024)
+
        /* We dynamically create a reader thread on demand. */
        mutex_lock(&h->request_mutex);
        if (!h->read_thr_exists) {
                sigset_t set, old_set;
+               pthread_attr_t attr;
+
+               if (pthread_attr_init(&attr) != 0) {
+                       mutex_unlock(&h->request_mutex);
+                       return false;
+               }
+               if (pthread_attr_setstacksize(&attr, READ_THREAD_STACKSIZE) != 
0) {
+                       pthread_attr_destroy(&attr);
+                       mutex_unlock(&h->request_mutex);
+                       return false;
+               }
 
                sigfillset(&set);
                pthread_sigmask(SIG_SETMASK, &set, &old_set);
 
-               if (pthread_create(&h->read_thr, NULL, read_thread, h) != 0) {
+               if (pthread_create(&h->read_thr, &attr, read_thread, h) != 0) {
                        pthread_sigmask(SIG_SETMASK, &old_set, NULL);
+                       pthread_attr_destroy(&attr);
                        mutex_unlock(&h->request_mutex);
                        return false;
                }
                h->read_thr_exists = 1;
                pthread_sigmask(SIG_SETMASK, &old_set, NULL);
+               pthread_attr_destroy(&attr);
        }
        mutex_unlock(&h->request_mutex);
 #endif

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