From: Ian Jackson <ian.jackson@eu.citrix.com>
Date: Fri, 11 Oct 2013 11:10:45 +0000 (+0100)
Subject: libxl: make libxl__poller_put tolerate p==NULL
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libxl: make libxl__poller_put tolerate p==NULL

This is less fragile, and more in keeping with the usual style of
initialising everything to 0 and freeing things unconditionally.

Correspondingly, remove the tests at the call sites.

Apropos of c1f3f174.  No overall functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---

diff --git a/tools/libxl/libxl_event.c b/tools/libxl/libxl_event.c
index 6f033dd4b3..a5c52bc510 100644
--- a/tools/libxl/libxl_event.c
+++ b/tools/libxl/libxl_event.c
@@ -1347,6 +1347,7 @@ libxl__poller *libxl__poller_get(libxl_ctx *ctx)
 
 void libxl__poller_put(libxl_ctx *ctx, libxl__poller *p)
 {
+    if (!p) return;
     LIBXL_LIST_INSERT_HEAD(&ctx->pollers_idle, p, entry);
 }
 
@@ -1476,8 +1477,7 @@ int libxl_event_wait(libxl_ctx *ctx, libxl_event **event_r,
     }
 
  out:
-    if (poller)
-        libxl__poller_put(ctx, poller);
+    libxl__poller_put(ctx, poller);
 
     CTX_UNLOCK;
     EGC_FREE;
@@ -1540,7 +1540,7 @@ void libxl__ao__destroy(libxl_ctx *ctx, libxl__ao *ao)
     AO_GC;
     if (!ao) return;
     LOG(DEBUG,"ao %p: destroy",ao);
-    if (ao->poller) libxl__poller_put(ctx, ao->poller);
+    libxl__poller_put(ctx, ao->poller);
     ao->magic = LIBXL__AO_MAGIC_DESTROYED;
     libxl__free_all(&ao->gc);
     free(ao);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 4e1505503c..165dc00287 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -829,7 +829,7 @@ _hidden void libxl__poller_dispose(libxl__poller *p);
  * away again afterwards.  _get can fail, returning NULL.
  * ctx must be locked. */
 _hidden libxl__poller *libxl__poller_get(libxl_ctx *ctx);
-_hidden void libxl__poller_put(libxl_ctx *ctx, libxl__poller *p);
+_hidden void libxl__poller_put(libxl_ctx*, libxl__poller *p /* may be NULL */);
 
 /* Notifies whoever is polling using p that they should wake up.
  * ctx must be locked. */