ahci: Fix crashes on duplicate BH registration

If ahci_dma_set_inactive is called a while there is still a pending BH
from a previous run, we will crash on the second run of
ahci_check_cmd_bh as it overwrites AHCIDevice::check_bh. Avoid this
broken and redundant duplicate registration.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index c6e0c7767e717dc668796160f26ff7c544903730..744d19d6db331946db984688b3a638e79e96a0bf 100644 (file)
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -1066,9 +1066,11 @@ static int ahci_dma_set_inactive(IDEDMA *dma)
 
     ad->dma_cb = NULL;
 
-    /* maybe we still have something to process, check later */
-    ad->check_bh = qemu_bh_new(ahci_check_cmd_bh, ad);
-    qemu_bh_schedule(ad->check_bh);
+    if (!ad->check_bh) {
+        /* maybe we still have something to process, check later */
+        ad->check_bh = qemu_bh_new(ahci_check_cmd_bh, ad);
+        qemu_bh_schedule(ad->check_bh);
+    }
 
     return 0;
 }