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Message-ID: <CAOD=uF4+F7MYO0cqd7ogmc=K9jtE5DX3wDoMv1eTxFq48JCX2g@mail.gmail.com>
Date: Thu, 8 Mar 2012 22:20:39 +0530
From: santosh prasad nayak <santoshprasadnayak@...il.com>
To: Mark Salyzyn <mark_salyzyn@...atex.com>
Cc: Jack Wang <jack_wang@...sh.com>, lindar_liu <lindar_liu@...sh.com>,
James Bottomley <JBottomley@...allels.com>,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-janitors@...r.kernel.org,
Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH 1/2] [SCSI] pm8001: Fix bogus interrupt state flag issue.
Hi Mark,
Thanks for your review.
Few queries:
1. Similar changes have been made in mpi_sata_completion() surrounding
spin_*lock_irq*(&t->task->state_lock)
Should those changes also need to revert back ?
>
> 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 then following block will enable IRQ.
2. I could not get this point.
If "SAS_TASK_STATE_ABORTED" task state condition occurs then following
block will enable IRQ.
if (unlikely((t->task_state_flags & SAS_TASK_STATE_ABORTED))) {
spin_unlock_irq(&t->task_state_lock);
// HERE IRQ will be enabled.
.......
pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
}
3. How bad will be "spin_lock_irq / spin_unlock_irq" in this case compared to
"spin_lock_irqsave / spin_unlock_irqrestore "
Regards
Santosh
>
> 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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