[PATCH] backends/tpm: Replace qemu_mutex_lock calls with QEMU_LOCK_GUARD

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Simplify the tpm_emulator_ctrlcmd() handler by replacing a pair of
qemu_mutex_lock/qemu_mutex_unlock calls by the WITH_QEMU_LOCK_GUARD
macro.

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Christophe de Dinechin <dinechin@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 backends/tpm/tpm_emulator.c | 34 +++++++++++++++-------------------
 1 file changed, 15 insertions(+), 19 deletions(-)

diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
index a012adc1934..e5f1063ab6c 100644
--- a/backends/tpm/tpm_emulator.c
+++ b/backends/tpm/tpm_emulator.c
@@ -30,6 +30,7 @@
 #include "qemu/error-report.h"
 #include "qemu/module.h"
 #include "qemu/sockets.h"
+#include "qemu/lockable.h"
 #include "io/channel-socket.h"
 #include "sysemu/tpm_backend.h"
 #include "sysemu/tpm_util.h"
@@ -124,31 +125,26 @@ static int tpm_emulator_ctrlcmd(TPMEmulator *tpm, unsigned long cmd, void *msg,
     uint32_t cmd_no = cpu_to_be32(cmd);
     ssize_t n = sizeof(uint32_t) + msg_len_in;
     uint8_t *buf = NULL;
-    int ret = -1;
 
-    qemu_mutex_lock(&tpm->mutex);
+    WITH_QEMU_LOCK_GUARD(&tpm->mutex) {
+        buf = g_alloca(n);
+        memcpy(buf, &cmd_no, sizeof(cmd_no));
+        memcpy(buf + sizeof(cmd_no), msg, msg_len_in);
 
-    buf = g_alloca(n);
-    memcpy(buf, &cmd_no, sizeof(cmd_no));
-    memcpy(buf + sizeof(cmd_no), msg, msg_len_in);
-
-    n = qemu_chr_fe_write_all(dev, buf, n);
-    if (n <= 0) {
-        goto end;
-    }
-
-    if (msg_len_out != 0) {
-        n = qemu_chr_fe_read_all(dev, msg, msg_len_out);
+        n = qemu_chr_fe_write_all(dev, buf, n);
         if (n <= 0) {
-            goto end;
+            return -1;
+        }
+
+        if (msg_len_out != 0) {
+            n = qemu_chr_fe_read_all(dev, msg, msg_len_out);
+            if (n <= 0) {
+                return -1;
+            }
         }
     }
 
-    ret = 0;
-
-end:
-    qemu_mutex_unlock(&tpm->mutex);
-    return ret;
+    return 0;
 }
 
 static int tpm_emulator_unix_tx_bufs(TPMEmulator *tpm_emu,
-- 
2.26.3