[Qemu-devel] [PATCH] target-ppc: fix warn_unused_result build break with in-kernel HTAB support

[Greg Kurz <gkurz@linux.vnet.ibm.com>]

The 7029677e4 commit introduced the following build break:

target-ppc/kvm.c: In function ‘kvmppc_hash64_write_pte’:
target-ppc/kvm.c:2017:10: error: ignoring return value of ‘write’, declared
with attribute warn_unused_result [-Werror=unused-result]
     write(htab_fd, &hpte_buf, sizeof(hpte_buf));
          ^

Even though nothing is done for the moment if kvm_htab_write() fails, we
obviously need to be explicit. Let's add an *empty* return path to please
gcc.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
---
 target-ppc/kvm.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 2eaf956..343376c 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -2012,9 +2012,15 @@ void kvmppc_hash64_write_pte(CPUPPCState *env, target_ulong pte_index,
     hpte_buf.hpte[0] = pte0;
     hpte_buf.hpte[1] = pte1;
     /*
-     * Write the hpte entry
+     * Write the hpte entry.
+     * CAUTION: write() has the warn_unused_result attribute. Hence we
+     * need to check the return value, even though we do nothing.
      */
-    write(htab_fd, &hpte_buf, sizeof(hpte_buf));
+    if (write(htab_fd, &hpte_buf, sizeof(hpte_buf)) < 0) {
+        goto out_close;
+    }
+
+out_close:
     close(htab_fd);
     return;