[Xen-devel] [PATCH] libxl: make libxl__poller_put tolerate p==NULL libxl_event_wait

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Ian Campbell writes ("Re: [PATCH v2] libxl: only put poller if already gotten 
in libxl_event_wait"):
> On Sun, 2013-09-29 at 18:24 +1300, Matthew Daley wrote:
> > Coverity-ID: 1055292
> > Signed-off-by: Matthew Daley <mattjd@xxxxxxxxx>
> 
> Acked + applied, thanks.

commit 9134bb273db4d55bec247d751b1de6e7876a7fe7
Author: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Date:   Fri Oct 11 12:10:45 2013 +0100

    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@xxxxxxxxxxxxx>

diff --git a/tools/libxl/libxl_event.c b/tools/libxl/libxl_event.c
index 6f033dd..a5c52bc 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 4e15055..165dc00 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. */

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