linux-kernel - [BUG] scsi: lpfc: possible ABBCCA deadlock involving three threads

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Message-ID: <af74e7e6-13dc-0695-e9e2-7dcd758d92f0@gmail.com>
Date:   Mon, 23 Aug 2021 19:31:55 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     james.smart@...adcom.com, dick.kennedy@...adcom.com,
        jejb@...ux.ibm.com, martin.petersen@...cle.com
Cc:     linux-scsi@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: [BUG] scsi: lpfc: possible ABBCCA deadlock involving three threads

Hello,

My static analysis tool reports a possible ABBCCA deadlock in the lpfc 
driver in Linux 5.10:

lpfc_els_flush_cmd()
   spin_lock(&pring->ring_lock); --> line 8124 (Lock A)
   lpfc_sli_cancel_iocbs()
     lpfc_sli_release_iocbq()
       spin_lock_irqsave(&phba->hbalock, iflags); --> line 1384 (Lock B)

lpfc_sli_abort_taskmgmt()
   spin_lock_irqsave(&phba->hbalock, iflags); --> line 11812 (Lock B)
   spin_lock(&lpfc_cmd->buf_lock); --> line 11830 (Lock C)

lpfc_abort_handler()
   spin_lock(&lpfc_cmd->buf_lock); --> line 4760 (Lock C)
   spin_lock(&pring_s4->ring_lock); --> line 4777 (Lock A)

When lpfc_els_flush_cmd(), lpfc_sli_abort_taskmgmt() and 
lpfc_abort_handler() 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 :)

Reported-by: TOTE Robot <oslab@...nghua.edu.cn>


Best wishes,
Jia-Ju Bai