blktap2: use sys/eventfd.h if it is available

arm64 only has the eventfd2 system call and using the libc wrapper when
available hides this from us. eventfd() has been in libc since glibc 2.8.

This code is already Linux specific.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/tools/blktap2/drivers/libaio-compat.h b/tools/blktap2/drivers/libaio-compat.h
index 353c36a869090f917800699183e7c51d6123b987..47cd96de94c78f8aece6ca52752cd4d6b2bb6d12 100644 (file)
--- a/tools/blktap2/drivers/libaio-compat.h
+++ b/tools/blktap2/drivers/libaio-compat.h
@@ -29,6 +29,7 @@
 #ifndef __LIBAIO_COMPAT
 #define __LIBAIO_COMPAT
 
+#include "../../config.h"
 #include <libaio.h>
 #include <unistd.h>
 #include <sys/syscall.h>
@@ -50,6 +51,16 @@ static inline void __io_set_eventfd(struct iocb *iocb, int eventfd)
        c->resfd = eventfd;
 }
 
+#ifdef HAVE_SYS_EVENTFD_H
+
+#include <sys/eventfd.h>
+
+static inline int tapdisk_sys_eventfd(int initval)
+{
+       return eventfd(initval, 0);
+}
+
+#else /* Fallback */
 #ifndef SYS_eventfd
 #ifndef __NR_eventfd
 # if defined(__alpha__)
@@ -88,5 +99,6 @@ static inline int tapdisk_sys_eventfd(int initval)
 {
        return syscall(SYS_eventfd, initval, 0);
 }
+#endif
 
 #endif /* __LIBAIO_COMPAT */

diff --git a/tools/config.h.in b/tools/config.h.in
index 08e337a1f5ce3d1cdf90b6d6fee4541681334502..a67910b57d4987f54e77a6c6e3a51ab9b9cea726 100644 (file)
--- a/tools/config.h.in
+++ b/tools/config.h.in
@@ -27,6 +27,9 @@
 /* Define to 1 if you have the <string.h> header file. */
 #undef HAVE_STRING_H
 
+/* Define to 1 if you have the <sys/eventfd.h> header file. */
+#undef HAVE_SYS_EVENTFD_H
+
 /* Define to 1 if you have the <sys/stat.h> header file. */
 #undef HAVE_SYS_STAT_H
 

diff --git a/tools/configure b/tools/configure
index 9f731724eac7fe7220ed92909280bf44fad1e532..a98dd9e0adc132cc41d8aa87b968e61c230debc8 100755 (executable)
--- a/tools/configure
+++ b/tools/configure
@@ -7817,12 +7817,13 @@ fi
 
 
 # Checks for header files.
-for ac_header in yajl/yajl_version.h
+for ac_header in yajl/yajl_version.h sys/eventfd.h
 do :
-  ac_fn_c_check_header_mongrel "$LINENO" "yajl/yajl_version.h" "ac_cv_header_yajl_yajl_version_h" "$ac_includes_default"
-if test "x$ac_cv_header_yajl_yajl_version_h" = x""yes; then :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
   cat >>confdefs.h <<_ACEOF
-#define HAVE_YAJL_YAJL_VERSION_H 1
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
 _ACEOF
 
 fi

diff --git a/tools/configure.ac b/tools/configure.ac
index f6e2fec2af60c198b49cb51b5da904d08c7deab1..36a3343b8719e3e928885d347c0e8ae4716b51ad 100644 (file)
--- a/tools/configure.ac
+++ b/tools/configure.ac
@@ -166,6 +166,6 @@ AC_CHECK_LIB([iconv], [libiconv_open], [libiconv="y"], [libiconv="n"])
 AC_SUBST(libiconv)
 
 # Checks for header files.
-AC_CHECK_HEADERS([yajl/yajl_version.h])
+AC_CHECK_HEADERS([yajl/yajl_version.h sys/eventfd.h])
 
 AC_OUTPUT()