[Qemu-devel] [PATCH] qemu-timer: Check for usable fields for SIGEV_THREAD_ID

[Richard Henderson <rth@twiddle.net>]

Older glibc (RHEL 5.x, Debian 5.x) does not have the _sigev_un._tid
member in its structure definition, while the accompanying kernel
headers do define SIGEV_THREAD_ID.  We need configure to check for
both before using it.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 configure    | 21 +++++++++++++++++++++
 qemu-timer.c |  4 ++--
 2 files changed, 23 insertions(+), 2 deletions(-)

FWIW, RHEL 5 is the last release for ia64.  And for whatever reason,
the ultrasparc in the gcc compile farm is still running Lenny.  I've
been hacking around this for some time, and now finally got around to
submitting a proper patch for it.


r~


diff --git a/configure b/configure
index c4a7837..78d8819 100755
--- a/configure
+++ b/configure
@@ -2841,6 +2841,23 @@ if compile_prog "" "" ; then
 fi
 
 ##########################################
+# check if we have usable SIGEV_THREAD_ID
+
+sigev_thread_id=no
+cat > $TMPC << EOF
+#include <signal.h>
+int main(void) {
+  struct sigevent ev;
+  ev.sigev_notify = SIGEV_THREAD_ID;
+  ev._sigev_un._tid = 0;
+  return 0;
+}
+EOF
+if compile_prog "" "" ; then
+    sigev_thread_id=yes
+fi
+
+##########################################
 # check if trace backend exists
 
 $python "$source_path/scripts/tracetool.py" "--backend=$trace_backend" --check-backend  > /dev/null 2> /dev/null
@@ -3186,6 +3203,7 @@ echo "preadv support    $preadv"
 echo "fdatasync         $fdatasync"
 echo "madvise           $madvise"
 echo "posix_madvise     $posix_madvise"
+echo "sigev_thread_id   $sigev_thread_id"
 echo "uuid support      $uuid"
 echo "libcap-ng support $cap_ng"
 echo "vhost-net support $vhost_net"
@@ -3469,6 +3487,9 @@ fi
 if test "$posix_madvise" = "yes" ; then
   echo "CONFIG_POSIX_MADVISE=y" >> $config_host_mak
 fi
+if test "$sigev_thread_id" = "yes" ; then
+  echo "CONFIG_SIGEV_THREAD_ID=y" >> $config_host_mak
+fi
 
 if test "$spice" = "yes" ; then
   echo "CONFIG_SPICE=y" >> $config_host_mak
diff --git a/qemu-timer.c b/qemu-timer.c
index 908a103..ede84ff 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -494,12 +494,12 @@ static int dynticks_start_timer(struct qemu_alarm_timer *t)
     memset(&ev, 0, sizeof(ev));
     ev.sigev_value.sival_int = 0;
     ev.sigev_notify = SIGEV_SIGNAL;
-#ifdef SIGEV_THREAD_ID
+#ifdef CONFIG_SIGEV_THREAD_ID
     if (qemu_signalfd_available()) {
         ev.sigev_notify = SIGEV_THREAD_ID;
         ev._sigev_un._tid = qemu_get_thread_id();
     }
-#endif /* SIGEV_THREAD_ID */
+#endif /* CONFIG_SIGEV_THREAD_ID */
     ev.sigev_signo = SIGALRM;
 
     if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
-- 
1.7.11.7