Allow to register a callback with fw_cfg_add_callback()

fw_cfg_add_callback() checks if key has FW_CFG_WRITE_CHANNEL bit set
after masking the key with FW_CFG_ENTRY_MASK.

But as FW_CFG_ENTRY_MASK is ~(FW_CFG_WRITE_CHANNEL | FW_CFG_ARCH_LOCAL),
the bit is never set and function exits.

This patch corrects this by checking the bit before masking the value.

Signed-by-off: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Gleb Natapov <gleb@redhat.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5978 c046a42c-6fe2-441c-8c8c-71466251a162

diff --git a/hw/fw_cfg.c b/hw/fw_cfg.c
index 4e68670..4333ed9 100644 (file)
--- a/hw/fw_cfg.c
+++ b/hw/fw_cfg.c
@@ -240,10 +240,12 @@ int fw_cfg_add_callback(void *opaque, uint16_t key, FWCfgCallback callback,
     FWCfgState *s = opaque;
     int arch = !!(key & FW_CFG_ARCH_LOCAL);
 
+    if (!(key & FW_CFG_WRITE_CHANNEL))
+        return 0;
+
     key &= FW_CFG_ENTRY_MASK;
 
-    if (key >= FW_CFG_MAX_ENTRY || !(key & FW_CFG_WRITE_CHANNEL)
-        || len > 65535)
+    if (key >= FW_CFG_MAX_ENTRY || len > 65535)
         return 0;
 
     s->entries[arch][key].data = data;