rgw: add pipe fd to set for select() in do_curl_wait()

when HAVE_CURL_MULTI_WAIT is 0, the pipe fd is never added to the
readfds for select(), so FD_ISSET() is always false. this prevents us
from ever trying to read from the fd, and the pipe's buffer eventually
fills up and deadlocks callers of RGWHTTPManager::signal_thread() when
they try to write to the pipe

Fixes: http://tracker.ceph.com/issues/16368
Signed-off-by: Casey Bodley <cbodley@redhat.com>
(cherry picked from commit 75897f82abde818fde6e1625c6977dcdd639a1f0)

diff --git a/src/rgw/rgw_http_client.cc b/src/rgw/rgw_http_client.cc
index 1661dd2f2ba315498e3838d9b899d4bbf4e9a09c..1212bb0b8761c68d4cbc9fec59fc8fe806f53f12 100644 (file)
--- a/src/rgw/rgw_http_client.cc
+++ b/src/rgw/rgw_http_client.cc
@@ -393,8 +393,11 @@ static int do_curl_wait(CephContext *cct, CURLM *handle, int signal_fd)
     return -EIO;
   }
 
-  if (signal_fd >= maxfd) {
-    maxfd = signal_fd + 1;
+  if (signal_fd > 0) {
+    FD_SET(signal_fd, &fdread);
+    if (signal_fd >= maxfd) {
+      maxfd = signal_fd + 1;
+    }
   }
 
   /* forcing a strict timeout, as the returned fdsets might not reference all fds we wait on */