libvhost-user: Declare uffdio_register early to make it C90 compliant

When using libvhost-user source in an external project that wants to
comply with the C90 standard, it is best to declare variables before
code.

  CC       libvhost-user.o
libvhost-user.c: In function ‘generate_faults’:
libvhost-user.c:683:9: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
  683 |         struct uffdio_register reg_struct;
      |         ^~~~~~

In this case, it is also simple enough and doesn't cause any extra
ifdef additions.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <556c2d00c01fa134d13c0371d4014c90694c2943.1671741278.git.marcel@holtmann.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c
index 211d31a4cc..bf92cc85c0 100644
--- a/subprojects/libvhost-user/libvhost-user.c
+++ b/subprojects/libvhost-user/libvhost-user.c
@@ -626,6 +626,8 @@ generate_faults(VuDev *dev) {
         VuDevRegion *dev_region = &dev->regions[i];
         int ret;
 #ifdef UFFDIO_REGISTER
+        struct uffdio_register reg_struct;
+
         /*
          * We should already have an open ufd. Mark each memory
          * range as ufd.
@@ -659,7 +661,7 @@ generate_faults(VuDev *dev) {
                     "%s: Failed to madvise(NOHUGEPAGE) region %d: %s\n",
                     __func__, i, strerror(errno));
         }
-        struct uffdio_register reg_struct;
+
         reg_struct.range.start = (uintptr_t)dev_region->mmap_addr;
         reg_struct.range.len = dev_region->size + dev_region->mmap_offset;
         reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;