Re: [Qemu-devel] ahci: crash after duplicate bh registration

[Jan Kiszka]

On 2011-05-09 16:31, Alexander Graf wrote:
> On 05/09/2011 04:26 PM, Kevin Wolf wrote:
>> Am 09.05.2011 16:12, schrieb Alexander Graf:
>>> On 05/08/2011 09:10 PM, Jan Kiszka wrote:
>>>> Hi Alex,
>>>>
>>>> I've seen crashes caused by ahci_check_cmd_bh unregistering a NULL bh.
>>>> It looks like ahci_dma_set_inactive can a called while there is already
>>>> a bh hanging around. Patch below cures the issue, but I have no clue if
>>>> such an invocation order is valid at all.
>>> It's certainly guest triggerable, so yes, let's check here.
>>>
>>> Acked-by: Alexander Graf<address@hidden>
>> Yes, the change makes sense to me. Please resend this as a proper patch,
>> Jan.

Will do.

>>
>> However, I still think Jan's question is valid: Is the AHCI emulation
>> supposed to run multiple DMA requests at once using the core.c
>> functions? I'd find it surprising if this actually worked well.
> 
> Not through the IDE core, no. There it can process a queue of IDE
> commands after each other or do NCQ, but that goes a different code
> patch, can do multiple requests at once though.
> 
> I'm not sure how this got triggered.

Forgot to mention: With a hacked-up q35 series. I may have broken
something there, or it was already broken (there are definitely bugs in
that series), so upstream might not expose the problem at all.

Jan

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