Re: [PATCH] scsi: lpfc: Fix potential deadlock on &phba->hbalock

[Justin Tee]

Hi Chengfeng,

That’s still a unlikely scenario:

        /* Check device state for handling interrupt */
        if (unlikely(lpfc_intr_state_check(phba))) {
                /* Check again for link_state with lock held */
                spin_lock_irqsave(&phba->hbalock, iflag);
                if (phba->link_state < LPFC_LINK_DOWN)
                        /* Flush, clear interrupt, and rearm the EQ */
                        lpfc_sli4_eqcq_flush(phba, fpeq);
                spin_unlock_irqrestore(&phba->hbalock, iflag);
                return IRQ_NONE;
        }

In order to enter that if statement and obtain the hbalock, the PCI
channel has to be offline or the HBA’s link is in not in an
initialized state.  If either of those were true, lpfc_cmpl_els_uvem
would never get called to begin with.

Thanks,
Justin


On Wed, Jul 26, 2023 at 10:40 PM Chengfeng Ye <dg573847474@xxxxxxxxx> wrote:
>
> Hi Justin,
>
> Thanks much for the reply,  it is my negligence of not have noticed it,
> and sorry for this.
>
> I inspect the bug report of my tool again and just find that actually
> lpfc_sli4_intr_handler() also acquires that lock.
>
> lpfc_sli4_intr_handler()
>     -> lpfc_sli4_hba_intr_handler()
>     -> spin_lock_irqsave(&phba->hbalock, iflag);
>
> It seems like this isr is called on an SLI4 type HBA. If consider this
> one could it be a deadlock problem?
>
> Thanks again,
> Chengfeng

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