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Re: [Qemu-devel] [PATCH for-2.8] megasas: do not call pci_dma_unmap afte

From: Stefan Hajnoczi
Subject: Re: [Qemu-devel] [PATCH for-2.8] megasas: do not call pci_dma_unmap after having freed the frame once
Date: Fri, 11 Nov 2016 12:47:23 +0000
User-agent: Mutt/1.7.1 (2016-10-04)

On Thu, Nov 10, 2016 at 04:27:50PM +0100, Paolo Bonzini wrote:
> Commit 8cc4678 ("megasas: remove useless check for cmd->frame", 2016-07-17) 
> was
> wrong because I trusted Coverity too much.  It turns out that there _is_ a
> path through which cmd->frame can become NULL.  After megasas_handle_frame's
> switch (md->frame->header.frame_cmd), megasas_init_firmware can be called.
> From there, megasas_reset_frames will call megasas_unmap_frame which resets
> cmd->frame = NULL.
> However, there is another bug to fix in there, because megasas_unmap_frame
> is called again after setting the command status.  In this case QEMU should
> not do anything, instead it calls pci_dma_unmap again.  Harmless, but
> better fix it.
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  hw/scsi/megasas.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Reviewed-by: Stefan Hajnoczi <address@hidden>

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