* [BUG] scsi: lpfc: possible ABBA deadlock
@ 2021-07-15 10:37 Jia-Ju Bai
2021-07-24 20:18 ` James Smart
0 siblings, 1 reply; 2+ messages in thread
From: Jia-Ju Bai @ 2021-07-15 10:37 UTC (permalink / raw)
To: james.smart, dick.kennedy, jejb, martin.petersen, linux-scsi,
linux-kernel
Hello,
I find there is a possible ABBA deadlock in the lpfc driver in Linux 5.10:
In lpfc_nvmet_unsol_fcp_issue_abort():
3502: spin_lock_irqsave(&ctxp->ctxlock, flags);
3504: spin_lock(&phba->sli4_hba.abts_nvmet_buf_list_lock);
In lpfc_sli4_nvmet_xri_aborted():
1787: spin_lock(&phba->sli4_hba.abts_nvmet_buf_list_lock);
1794: spin_lock(&ctxp->ctxlock);
When lpfc_nvmet_unsol_fcp_issue_abort() and
lpfc_sli4_nvmet_xri_aborted() are concurrently executed, the deadlock
can occur.
I am not quite sure whether this possible deadlock is real and how to
fix it if it is real.
Any feedback would be appreciated, thanks :)
Best wishes,
Jia-Ju Bai
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [BUG] scsi: lpfc: possible ABBA deadlock
2021-07-15 10:37 [BUG] scsi: lpfc: possible ABBA deadlock Jia-Ju Bai
@ 2021-07-24 20:18 ` James Smart
0 siblings, 0 replies; 2+ messages in thread
From: James Smart @ 2021-07-24 20:18 UTC (permalink / raw)
To: Jia-Ju Bai, james.smart, dick.kennedy, jejb, martin.petersen,
linux-scsi, linux-kernel
On 7/15/2021 3:37 AM, Jia-Ju Bai wrote:
> Hello,
>
> I find there is a possible ABBA deadlock in the lpfc driver in Linux 5.10:
>
> In lpfc_nvmet_unsol_fcp_issue_abort():
> 3502: spin_lock_irqsave(&ctxp->ctxlock, flags);
> 3504: spin_lock(&phba->sli4_hba.abts_nvmet_buf_list_lock);
>
> In lpfc_sli4_nvmet_xri_aborted():
> 1787: spin_lock(&phba->sli4_hba.abts_nvmet_buf_list_lock);
> 1794: spin_lock(&ctxp->ctxlock);
>
> When lpfc_nvmet_unsol_fcp_issue_abort() and
> lpfc_sli4_nvmet_xri_aborted() are concurrently executed, the deadlock
> can occur.
>
> I am not quite sure whether this possible deadlock is real and how to
> fix it if it is real.
> Any feedback would be appreciated, thanks :)
>
>
> Best wishes,
> Jia-Ju Bai
Jia-Ju,
It's a valid issue, but rather difficult to actually occur. We've put
together a fix and am testing it. Will post when ready.
-- james
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