net: cadence_gem: Fix Tx descriptor update

The local variable "desc" was being used to read-modify-write the
first descriptor (of a multi-desc packet) upon packet completion.
desc however continues to be used by the code as the current
descriptor. Give this first desc RMW it's own local variable to
avoid trampling.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
index a26861e2ae06ead4f6be7acab3e836779bc51695..5335db874f9b8bb59ec3d4b13c67fecf73af403c 100644 (file)
--- a/hw/net/cadence_gem.c
+++ b/hw/net/cadence_gem.c
@@ -911,14 +911,16 @@ static void gem_transmit(GemState *s)
 
         /* Last descriptor for this packet; hand the whole thing off */
         if (tx_desc_get_last(desc)) {
+            unsigned    desc_first[2];
+
             /* Modify the 1st descriptor of this packet to be owned by
              * the processor.
              */
-            cpu_physical_memory_read(s->tx_desc_addr,
-                                     (uint8_t *)&desc[0], sizeof(desc));
-            tx_desc_set_used(desc);
-            cpu_physical_memory_write(s->tx_desc_addr,
-                                      (uint8_t *)&desc[0], sizeof(desc));
+            cpu_physical_memory_read(s->tx_desc_addr, (uint8_t *)desc_first,
+                                     sizeof(desc_first));
+            tx_desc_set_used(desc_first);
+            cpu_physical_memory_write(s->tx_desc_addr, (uint8_t *)desc_first,
+                                      sizeof(desc_first));
             /* Advance the hardare current descriptor past this packet */
             if (tx_desc_get_wrap(desc)) {
                 s->tx_desc_addr = s->regs[GEM_TXQBASE];