diff --git a/ChangeLog b/ChangeLog
index 6c3fce55e4..253f8b0533 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Sun Jun 12 11:16:59 2011  Tanaka Akira  <akr@fsij.org>
+
+	* io.c: use select() appropriately for sendfile().
+	  Fixed by Eric Wong.  [ruby-core:36150]
+	  (maygvl_copy_stream_wait_readwrite): removed.
+	  (nogvl_copy_stream_sendfile): use nogvl_copy_stream_wait_write and
+	  maygvl_copy_stream_wait_read instead of
+	  maygvl_copy_stream_wait_readwrite.
+
 Sun Jun 12 09:32:13 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* atomic.h (ATOMIC_OR): _InterlockedOr is not available on migw.
diff --git a/io.c b/io.c
index 3618ac2321..3ce4832988 100644
--- a/io.c
+++ b/io.c
@@ -8648,22 +8648,6 @@ simple_sendfile(int out_fd, int in_fd, off_t *offset, off_t count)
 #endif
 
 #ifdef USE_SENDFILE
-static int
-maygvl_copy_stream_wait_readwrite(int has_gvl, struct copy_stream_struct *stp)
-{
-    int ret;
-    rb_fd_zero(&stp->fds);
-    rb_fd_set(stp->src_fd, &stp->fds);
-    rb_fd_set(stp->dst_fd, &stp->fds);
-    ret = maygvl_select(has_gvl, rb_fd_max(&stp->fds), &stp->fds, NULL, NULL, NULL);
-    if (ret == -1) {
-        stp->syserr = "select";
-        stp->error_no = errno;
-        return -1;
-    }
-    return 0;
-}
-
 static int
 nogvl_copy_stream_sendfile(struct copy_stream_struct *stp)
 {
@@ -8746,7 +8730,18 @@ nogvl_copy_stream_sendfile(struct copy_stream_struct *stp)
 #if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
 	  case EWOULDBLOCK:
 #endif
-            if (maygvl_copy_stream_wait_readwrite(0, stp) == -1)
+#ifndef linux
+           /*
+            * Linux requires stp->src_fd to be a mmap-able (regular) file,
+            * select() reports regular files to always be "ready", so
+            * there is no need to select() on it.
+            * Other OSes may have the same limitation for sendfile() which
+            * allow us to bypass maygvl_copy_stream_wait_read()...
+            */
+            if (maygvl_copy_stream_wait_read(0, stp) == -1)
+                return -1;
+#endif
+            if (nogvl_copy_stream_wait_write(stp) == -1)
                 return -1;
             goto retry_sendfile;
         }