RE: pm8001: locking in mpi_sata_completion() is broken
>
> The locking in mpi_sata_completion() is broken. I'm not sure what was
> intended at all. Here is what it does:
>
> 1876 mpi_sata_completion(struct pm8001_hba_info *pm8001_ha, void
*piomb)
> 1877 {
> 1878 struct sas_task *t;
> 1879 struct pm8001_ccb_info *ccb;
> 1880 unsigned long flags = 0;
> ^^^^^^^^^^^^^^^^^^^^^^^
> This is bogus. The flags should be set with irqsave. This implies a
> knowledge of the internals which should be abstracted away.
>
[Jack Wang]
Hi Dan,
Thanks for point out this. Other comments answer below.
> [snip]
>
> 2006 case IO_OPEN_CNX_ERROR_IT_NEXUS_LOSS:
> 2007 PM8001_IO_DBG(pm8001_ha,
> 2008
> pm8001_printk("IO_OPEN_CNX_ERROR_IT_NEXUS_LOSS\n"));
> 2009 ts->resp = SAS_TASK_COMPLETE;
> 2010 ts->stat = SAS_DEV_NO_RESPONSE;
> 2011 if (!t->uldd_task) {
> 2012 pm8001_handle_event(pm8001_ha,
> 2013 pm8001_dev,
> 2014 IO_OPEN_CNX_ERROR_IT_NEXUS_LOSS);
> 2015 ts->resp = SAS_TASK_UNDELIVERED;
> 2016 ts->stat = SAS_QUEUE_FULL;
> 2017 pm8001_ccb_task_free(pm8001_ha, t, ccb,
> tag);
> 2018 mb();/*in order to force CPU ordering*/
> 2019 spin_unlock_irqrestore(&pm8001_ha->lock,
> flags);
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Calling irqrestore before we've done an irqsave. What are we trying to
> restore?
[Jack Wang]
We hold spin_lock_irqsave when we process interrupt, so here we need restore
it to do task done clean.
>
> 2020 t->task_done(t);
> 2021 spin_lock_irqsave(&pm8001_ha->lock,
> flags);
> 2022 return;
> 2023 }
>
> [snip]
>
> 2197 spin_unlock_irqrestore(&t->task_state_lock,
> flags);
> 2198 pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
> 2199 mb();/*ditto*/
> 2200 spin_unlock_irqrestore(&pm8001_ha->lock, flags);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> We just called irqrestore so there is no need to restore it twice.
>
> 2201 t->task_done(t);
> 2202 spin_lock_irqsave(&pm8001_ha->lock, flags);
> ^^^^^
> We're saving the irq status but we're at the end of the function so we
> never use it again.
>
> 2203 }
> 2204 }
>
> I've just picked out a couple examples, but basically the whole function
> is like that.
[Jack Wang]
Others are basically the same, what we want is make the lock balance.
Thanks.
>
> regards,
> dan carpenter
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