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[143.89.191.97]) by smtp.gmail.com with ESMTPSA id c9-20020a170902c1c900b001bb8be10a84sm9100254plc.304.2023.07.26.11.13.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jul 2023 11:13:32 -0700 (PDT) From: Chengfeng Ye To: james.smart@broadcom.com, dick.kennedy@broadcom.com, jejb@linux.ibm.com, martin.petersen@oracle.com, sumit.semwal@linaro.org, christian.koenig@amd.com, justin.tee@broadcom.com Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Chengfeng Ye Subject: [PATCH v2] scsi: lpfc: Fix potential deadlock on &ndlp->lock Date: Wed, 26 Jul 2023 18:13:22 +0000 Message-Id: <20230726181322.26754-1-dg573847474@gmail.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org As &ndlp->lock is acquired by timer lpfc_els_retry_delay() under softirq context, process context code acquiring the lock &ndlp->lock should disable irq or bh, otherwise deadlock could happen if the timer preempt the execution while the lock is held in process context on the same CPU. The two lock acquisition inside lpfc_cleanup_pending_mbox() does not disable irq or softirq. [Deadlock Scenario] lpfc_cmpl_els_fdisc() -> lpfc_cleanup_pending_mbox() -> spin_lock(&ndlp->lock); -> lpfc_els_retry_delay() -> lpfc_nlp_get() -> spin_lock_irqsave(&ndlp->lock, flags); (deadlock here) This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock. The patch fix the potential deadlock by spin_lock_irq() to disable irq. Signed-off-by: Chengfeng Ye --- drivers/scsi/lpfc/lpfc_sli.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c index 58d10f8f75a7..8555f6bb9742 100644 --- a/drivers/scsi/lpfc/lpfc_sli.c +++ b/drivers/scsi/lpfc/lpfc_sli.c @@ -21049,9 +21049,9 @@ lpfc_cleanup_pending_mbox(struct lpfc_vport *vport) mb->mbox_flag |= LPFC_MBX_IMED_UNREG; restart_loop = 1; spin_unlock_irq(&phba->hbalock); - spin_lock(&ndlp->lock); + spin_lock_irq(&ndlp->lock); ndlp->nlp_flag &= ~NLP_IGNR_REG_CMPL; - spin_unlock(&ndlp->lock); + spin_unlock_irq(&ndlp->lock); spin_lock_irq(&phba->hbalock); break; } @@ -21067,9 +21067,9 @@ lpfc_cleanup_pending_mbox(struct lpfc_vport *vport) ndlp = (struct lpfc_nodelist *)mb->ctx_ndlp; mb->ctx_ndlp = NULL; if (ndlp) { - spin_lock(&ndlp->lock); + spin_lock_irq(&ndlp->lock); ndlp->nlp_flag &= ~NLP_IGNR_REG_CMPL; - spin_unlock(&ndlp->lock); + spin_unlock_irq(&ndlp->lock); lpfc_nlp_put(ndlp); } }