megasas: do not call pci_dma_unmap after having freed the frame once
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 <pbonzini@redhat.com>
diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
index 52a4123..ca62952 100644
--- a/hw/scsi/megasas.c
+++ b/hw/scsi/megasas.c
@@ -461,9 +461,12 @@
{
PCIDevice *p = PCI_DEVICE(s);
- pci_dma_unmap(p, cmd->frame, cmd->pa_size, 0, 0);
+ if (cmd->pa_size) {
+ pci_dma_unmap(p, cmd->frame, cmd->pa_size, 0, 0);
+ }
cmd->frame = NULL;
cmd->pa = 0;
+ cmd->pa_size = 0;
clear_bit(cmd->index, s->frame_map);
}
