On Tue, May 31, 2016 at 8:21 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> On Tue, May 31, 2016 at 1:38 AM, Wei Fang <fangwei1@xxxxxxxxxx> wrote:
>> sas_ata_strategy_handler() adds the works of the ata error handler
>> to system_unbound_wq. This workqueue asynchronously runs work items,
>> so the ata error handler will be performed concurrently on different
>> CPUs. In this case, ->host_failed will be decreased simultaneously in
>> scsi_eh_finish_cmd() on different CPUs, and become abnormal.
>>
>> It will lead to permanently inequal between ->host_failed and
>> ->host_busy, and scsi error handler thread won't become running.
>> IO errors after that won't be handled forever.
>>
>> Use atomic type for ->host_failed to fix this race.
>>
>> This fixes the problem introduced in
>> commit 50824d6c5657 ("[SCSI] libsas: async ata-eh").
>>
>> Reviewed-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
>> Signed-off-by: Wei Fang <fangwei1@xxxxxxxxxx>
>
> Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Should also tag this for -stable.
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