swtpm: cuse: Lock file_ops_lock before reading tpm_running

Lock the file_ops_lock before reading the tpm_running variable so that
access to access to it is serialized among all possible threads.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

src/swtpm/cuse_tpm.c

@@ -1081,6 +1081,9 @@ static void ptm_ioctl(fuse_req_t req, int cmd, void *arg,
     ptm_init *init_p;
     TPM_MODIFIER_INDICATOR orig_locality;
 
+    /* prevent other threads from writing or doing ioctls */
+    g_mutex_lock(FILE_OPS_LOCK);
+
     /* some commands have to wait until the worker thread is done */
     switch(cmd) {
     case PTM_GET_CAPABILITY:
@@ -1106,9 +1109,6 @@ static void ptm_ioctl(fuse_req_t req, int cmd, void *arg,
         break;
     }
 
-    /* prevent other threads from writing or doing ioctls */
-    g_mutex_lock(FILE_OPS_LOCK);
-
     switch (cmd) {
     case PTM_GET_CAPABILITY:
         if (out_bufsz != sizeof(ptm_cap)) {