From 7d8185ccbb8051a72ccdb18480fdb4af8fa9feae Mon Sep 17 00:00:00 2001
From: Marc Alexander Lehmann <libev@schmorp.de>
Date: Fri, 22 Nov 2019 14:32:13 +0000
Subject: [PATCH] *** empty log message ***

---
 Changes  |  5 +++++
 ev.c     | 23 ++++++++++++++++++++---
 libev.m4 |  8 ++++++--
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/Changes b/Changes
index 962d561..0ab34fd 100644
--- a/Changes
+++ b/Changes
@@ -4,6 +4,11 @@ TODO: revisit 59.x timer in the light of modern powersaving
 TODO: maybe use timerfd to detect time jumps on linux
 TODO: document EV_TSTAMP_T
 
+4.29
+	- (libev) add io uring autoconf and non-autoconf detection,
+          the latter of which should disable io_uring compilation
+          on old systems.
+
 4.28 (EV only)
 	- linuxaio backend resulted in random memory corruption
           when loop is forked.
diff --git a/ev.c b/ev.c
index 162b659..3b80a2d 100644
--- a/ev.c
+++ b/ev.c
@@ -126,6 +126,15 @@
 #  define EV_USE_LINUXAIO 0
 # endif
    
+# if HAVE_LINUX_FS_H && HAVE_SYS_TIMERFD_H && HAVE_KERNEL_RWF_T
+#  ifndef EV_USE_IOURING
+#   define EV_USE_IOURING EV_FEATURE_BACKENDS
+#  endif
+# else
+#  undef EV_USE_IOURING
+#  define EV_USE_IOURING 0
+# endif
+ 
 # if HAVE_KQUEUE && HAVE_SYS_EVENT_H
 #  ifndef EV_USE_KQUEUE
 #   define EV_USE_KQUEUE EV_FEATURE_BACKENDS
@@ -170,7 +179,7 @@
 #  undef EV_USE_EVENTFD
 #  define EV_USE_EVENTFD 0
 # endif
- 
+
 #endif
 
 /* OS X, in its infinite idiocy, actually HARDCODES
@@ -335,8 +344,8 @@
 #endif
 
 #ifndef EV_USE_IOURING
-# if __linux
-#  define EV_USE_IOURING 0
+# if __linux /* later checks might disable again */
+#  define EV_USE_IOURING 1
 # else
 #  define EV_USE_IOURING 0
 # endif
@@ -440,6 +449,14 @@
 # define EV_USE_INOTIFY 0
 #endif
 
+#if __linux && EV_USE_IOURING
+# include <linux/fs.h>
+# ifndef RWF_SYNC
+#  undef EV_USE_IOURING
+#  define EV_USE_IOURING 0
+# endif
+#endif
+
 #if !EV_USE_NANOSLEEP
 /* hp-ux has it in sys/time.h, which we unconditionally include above */
 # if !defined _WIN32 && !defined __hpux
diff --git a/libev.m4 b/libev.m4
index 642e7b1..f859eff 100644
--- a/libev.m4
+++ b/libev.m4
@@ -2,8 +2,8 @@ dnl this file is part of libev, do not make local modifications
 dnl http://software.schmorp.de/pkg/libev
 
 dnl libev support
-AC_CHECK_HEADERS(sys/inotify.h sys/epoll.h sys/event.h port.h poll.h)
-AC_CHECK_HEADERS(sys/select.h sys/eventfd.h sys/signalfd.h linux/aio_abi.h)
+AC_CHECK_HEADERS(sys/inotify.h sys/epoll.h sys/event.h port.h poll.h sys/timerfd.h)
+AC_CHECK_HEADERS(sys/select.h sys/eventfd.h sys/signalfd.h linux/aio_abi.h linux/fs.h)
  
 AC_CHECK_FUNCS(inotify_init epoll_ctl kqueue port_create poll select eventfd signalfd)
  
@@ -36,6 +36,10 @@ AC_CHECK_FUNCS(nanosleep, [], [
    fi
 ])
 
+AC_CHECK_TYPE(__kernel_rwf_t, [
+   AC_DEFINE(HAVE_KERNEL_RWF_T, 1, Define to 1 if linux/fs.h defined kernel_rwf_t)
+], [], [#include <linux/fs.h>])
+
 if test -z "$LIBEV_M4_AVOID_LIBM"; then
    LIBM=m
 fi