linux-kernel - Re: Re: [PATCH 1/2] [SCSI] pm8001: Fix bogus interrupt state flag issue.

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Message-ID: <201203082215017182231@usish.com>
Date:	Thu, 8 Mar 2012 22:15:03 +0800
From:	jack_wang <jack_wang@...sh.com>
To:	"Mark Salyzyn" <mark_salyzyn@...atex.com>,
	"santosh nayak" <santoshprasadnayak@...il.com>
Cc:	"Mark Salyzyn" <mark_salyzyn@...atex.com>,
	lindar_liu <lindar_liu@...sh.com>,
	"James Bottomley" <JBottomley@...allels.com>,
	linux-scsi <linux-scsi@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	kernel-janitors <kernel-janitors@...r.kernel.org>,
	"Dan Carpenter" <dan.carpenter@...cle.com>
Subject: Re: Re: [PATCH 1/2] [SCSI] pm8001: Fix bogus interrupt state flag issue.

Thanks Mark for look into this.You're right. The change for task_state_lock is not right.
Sorry for not look carefully about the change.



--------------
jack_wang
>NAK
>
>In the fragment below, the 'spin_lock_irqsave(&t->task_state_lock, flags);' is 100% legitimate. The change you did was not inert, and result in the IRQ being disabled upon exit should a SAS_TASK_STATE_ABORTED task state condition occur.
>
>I propose (annotated below) you leave the flags automatic variable, but uninitialized. The changes surrounding spin_*lock_irq*(&pm8001_ha->lock, flags) are OK, but revert back the changes surrounding the spin_*lock_irq*(&t->task->state_lock,flags) so that lock would be properly nested.
>
>To be pedantic, and to be more correct, this code should have spawned a work queue task to perform the t->task_done(t) operation in a separate thread rather than inline and precariously unlocked; but that would be beyond the scope of these changes and should be left for future work to decide if it is even necessary. Not sure how such a change would affect performance (using the work queue) ... so I am 'afraid' of pushing such a change in any case given the relatively reliable operation of this driver (and the dynamic nature of the changes Dan is making to the SATA side of things for instance ;-} ).
>
>I am sorry for taking so long to get to the task of reviewing this (and the previous) code. I look forward to your comments.
>
>Sincerely -- Mark Salyzyn
>
>On Feb 26, 2012, at 8:33 AM, santosh nayak wrote:
>
>> @@ -2207,7 +2206,6 @@ mpi_sata_completion(struct pm8001_hba_info *pm8001_ha, void *piomb)
>> static void mpi_sata_event(struct pm8001_hba_info *pm8001_ha , void *piomb)
>> {
>> 	struct sas_task *t;
>> -	unsigned long flags = 0;
>MGS>	unsigned long flags;
>> 	struct task_status_struct *ts;
>> 	struct pm8001_ccb_info *ccb;
>> 	struct pm8001_device *pm8001_dev;
>> @@ -2287,9 +2285,9 @@ static void mpi_sata_event(struct pm8001_hba_info *pm8001_ha , void *piomb)
>> 			ts->stat = SAS_QUEUE_FULL;
>> 			pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
>> 			mb();/*ditto*/
>> -			spin_unlock_irqrestore(&pm8001_ha->lock, flags);
>> +			spin_unlock_irq(&pm8001_ha->lock);
>> 			t->task_done(t);
>> -			spin_lock_irqsave(&pm8001_ha->lock, flags);
>> +			spin_lock_irq(&pm8001_ha->lock);
>> 			return;
>> 		}
>> 		break;
>> @@ -2387,31 +2385,31 @@ static void mpi_sata_event(struct pm8001_hba_info *pm8001_ha , void *piomb)
>> 		ts->stat = SAS_OPEN_TO;
>> 		break;
>> 	}
>> -	spin_lock_irqsave(&t->task_state_lock, flags);
>> +	spin_lock_irq(&t->task_state_lock);
>MGS>	spin_lock_irqsave(&t->task_state_lock, flags);
>> 	t->task_state_flags &= ~SAS_TASK_STATE_PENDING;
>> 	t->task_state_flags &= ~SAS_TASK_AT_INITIATOR;
>> 	t->task_state_flags |= SAS_TASK_STATE_DONE;
>> 	if (unlikely((t->task_state_flags & SAS_TASK_STATE_ABORTED))) {
>> -		spin_unlock_irqrestore(&t->task_state_lock, flags);
>> +		spin_unlock_irq(&t->task_state_lock);
>MGS>		spin_unlock_irqrestore(&t->task_state_lock, flags);
>> 		PM8001_FAIL_DBG(pm8001_ha,
>> 			pm8001_printk("task 0x%p done with io_status 0x%x"
>> 			" resp 0x%x stat 0x%x but aborted by upper layer!\n",
>> 			t, event, ts->resp, ts->stat));
>> 		pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
>> 	} else if (t->uldd_task) {
>> -		spin_unlock_irqrestore(&t->task_state_lock, flags);
>> +		spin_unlock_irq(&t->task_state_lock);
>> 		pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
>> 		mb();/* ditto */
>> -		spin_unlock_irqrestore(&pm8001_ha->lock, flags);
>> +		spin_unlock_irq(&pm8001_ha->lock);
>> 		t->task_done(t);
>> -		spin_lock_irqsave(&pm8001_ha->lock, flags);
>> +		spin_lock_irq(&pm8001_ha->lock);
>> 	} else if (!t->uldd_task) {
>> -		spin_unlock_irqrestore(&t->task_state_lock, flags);
>> +		spin_unlock_irq(&t->task_state_lock);
>> 		pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
>> 		mb();/*ditto*/
>> -		spin_unlock_irqrestore(&pm8001_ha->lock, flags);
>> +		spin_unlock_irq(&pm8001_ha->lock);
>> 		t->task_done(t);
>> -		spin_lock_irqsave(&pm8001_ha->lock, flags);
>> +		spin_lock_irq(&pm8001_ha->lock);
>> 	}
>> }
>
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