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dma-helpers: Fix race condition of continue_after_map_failure and dma_aio_cancel

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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>
This commit is contained in:
Fam Zheng 2015-03-16 17:03:37 +08:00 • committed by Paolo Bonzini
parent 33b6c2edf6
commit e95205e1f9
3 changed files with 31 additions and 23 deletions
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3
include/exec/cpu-common.h
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@ -82,7 +82,8 @@ void *cpu_physical_memory_map(hwaddr addr,
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);