Avoid a race condition in url-queue-kill-job

* url-queue.el (url-queue-kill-job): Delete the process sentinel
before killing the process to avoid a race condition between the
two processes killing off the process buffer.

2 files changed, 9 insertions, 3 deletions

diff --git a/lisp/url/ChangeLog b/lisp/url/ChangeLog
index e57b5eccbc2..55aa9194904 100644
--- a/lisp/url/ChangeLog
+++ b/lisp/url/ChangeLog
@@ -1,5 +1,9 @@
 2012-02-20  Lars Ingebrigtsen  <larsi@gnus.org>
 
+        * url-queue.el (url-queue-kill-job): Delete the process sentinel
+        before killing the process to avoid a race condition between the
+        two processes killing off the process buffer.
+
         * url.el (url-retrieve-internal): Warn about file errors when
         pruning the cache instead of bugging out (bug#10831).
 
diff --git a/lisp/url/url-queue.el b/lisp/url/url-queue.el
index 6456d44c423..6e4cedddaf3 100644
--- a/lisp/url/url-queue.el
+++ b/lisp/url/url-queue.el
@@ -152,9 +152,11 @@ The variable `url-queue-timeout' sets a timeout."
 
 (defun url-queue-kill-job (job)
   (when (bufferp (url-queue-buffer job))
-    (while (get-buffer-process (url-queue-buffer job))
-      (ignore-errors
-        (delete-process (get-buffer-process (url-queue-buffer job)))))
+    (let (process)
+      (while (setq process (get-buffer-process (url-queue-buffer job)))
+        (set-process-sentinel process 'ignore)
+        (ignore-errors
+          (delete-process process))))
     (ignore-errors
       (kill-buffer (url-queue-buffer job)))))