[Qemu-devel] [PATCH] Allow to register a callback with fw_cfg_add_callback()

[Laurent Vivier]

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 <address@hidden>
---
 hw/fw_cfg.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Index: qemu/hw/fw_cfg.c
===================================================================
--- qemu.orig/hw/fw_cfg.c       2008-12-11 15:55:15.000000000 +0100
+++ qemu/hw/fw_cfg.c    2008-12-11 15:55:41.000000000 +0100
@@ -240,10 +240,12 @@ int fw_cfg_add_callback(void *opaque, ui
     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;