commit e95205e1f9cd2c4262b7a7b1c992a94512c86d0e
author Fam Zheng <famz@redhat.com> Mon Mar 16 17:03:37 2015 +0800
committer Paolo Bonzini <pbonzini@redhat.com> Mon Apr 27 18:24:18 2015 +0200
tree 1c03e53eeb46e2d7c15b9c15a1f1c9414e254e6e
parent 33b6c2edf6214f02b9beaea61b169506c01f90aa

dma-helpers: Fix race condition of continue_after_map_failure and dma_aio_cancel

If DMA's owning thread cancels the IO while the bounce buffer's owning thread
is notifying the "cpu client list", a use-after-free happens:

     continue_after_map_failure               dma_aio_cancel
     ------------------------------------------------------------------
     aio_bh_new
                                              qemu_bh_delete
     qemu_bh_schedule (use after free)

Also, the old code doesn't run the bh in the right AioContext.

Fix both problems by passing a QEMUBH to cpu_register_map_client.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1426496617-10702-6-git-send-email-famz@redhat.com>
[Remove unnecessary forward declaration. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/exec/cpu-common.h

diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index fcc3162..43428bd 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -82,7 +82,8 @@
                               int is_write);
 void cpu_physical_memory_unmap(void *buffer, hwaddr len,
                                int is_write, hwaddr access_len);
-void *cpu_register_map_client(void *opaque, void (*callback)(void *opaque));
+void cpu_register_map_client(QEMUBH *bh);
+void cpu_unregister_map_client(QEMUBH *bh);
 
 bool cpu_physical_memory_is_io(hwaddr phys_addr);