On 05/22/14 18:22, Paolo Bonzini wrote:
> Il 21/05/2014 15:30, Bart Van Assche ha scritto:
>> +static bool scmd_being_handled_in_other_context(struct scsi_cmnd *scmd)
>> +{
>> + struct Scsi_Host *shost = scmd->device->host;
>> + struct scsi_cmnd *c;
>> + unsigned long flags;
>> + bool ret = false;
>> +
>> + if (!blk_rq_completed(scmd->request))
>> + return true;
>> +
>> + spin_lock_irqsave(shost->host_lock, flags);
>> + list_for_each_entry(c, &shost->eh_cmd_q, eh_entry) {
>> + if (c == scmd) {
>> + ret = true;
>> + break;
>> + }
>> + }
>> + spin_unlock_irqrestore(shost->host_lock, flags);
>> +
>> + return ret;
>> +}
>> +
>> /**
>> * scmd_eh_abort_handler - Handle command aborts
>> * @work: command to be aborted.
>> @@ -120,6 +142,8 @@ scmd_eh_abort_handler(struct work_struct *work)
>> struct scsi_device *sdev = scmd->device;
>> int rtn;
>>
>> + WARN_ON_ONCE(scmd_being_handled_in_other_context(scmd));
>
> What about a simpler, though less accuracte
>
> WARN_ON(!blk_rq_completed(scmd->request));
>
> that doesn't need the host_lock?
One reason why I posted this patch as an RFC was to invite feedback. I'm
fine with leaving out the loop over the eh_cmd_q list although I do not
expect that will make a significant performance difference. None of the
functions in which a check was added are in the hot path.
Bart.
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