| Message ID | 20230726155342.51623-1-dg573847474@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | scsi: lpfc: Fix potential deadlock on &phba->hbalock | expand |
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
diff --git a/drivers/scsi/lpfc/lpfc_els.c b/drivers/scsi/lpfc/lpfc_els.c index 2bad9954c355..9667b4937b3a 100644 --- a/drivers/scsi/lpfc/lpfc_els.c +++ b/drivers/scsi/lpfc/lpfc_els.c @@ -12398,6 +12398,7 @@ lpfc_cmpl_els_uvem(struct lpfc_hba *phba, struct lpfc_iocbq *icmdiocb, u32 ulp_word4 = get_job_word4(phba, rspiocb); struct lpfc_dmabuf *dmabuf = icmdiocb->cmd_dmabuf; struct lpfc_vmid *vmid; + unsigned long flags; vmid = vmid_context->vmp; if (!ndlp || ndlp->nlp_state != NLP_STE_UNMAPPED_NODE) @@ -12419,11 +12420,11 @@ lpfc_cmpl_els_uvem(struct lpfc_hba *phba, struct lpfc_iocbq *icmdiocb, ulp_status, ulp_word4); goto out; } - spin_lock(&phba->hbalock); + spin_lock_irqsave(&phba->hbalock, flags); /* Set IN USE flag */ vport->vmid_flag |= LPFC_VMID_IN_USE; phba->pport->vmid_flag |= LPFC_VMID_IN_USE; - spin_unlock(&phba->hbalock); + spin_unlock_irqrestore(&phba->hbalock, flags); if (vmid_context->instantiated) { write_lock(&vport->vmid_lock);
As &phba->hbalock is acquired by hardirq such as lpfc_sli_intr_handler(), process context code acquiring the lock &phba->hbalock should disable irq, otherwise deadlock could happen if the irq preempt the execution while the lock is held in process context on the same CPU. Most lock acquicision site disables irq but inside the callback lpfc_cmpl_els_uvem() the lock is acquired without explicitly disable irq. The outside caller of this callback also seems not disable irq. [Deadlock Scenario] lpfc_cmpl_els_uvem() -> spin_lock(&phba->hbalock) <irq> -> lpfc_sli_intr_handle() -> spin_lock(&phba->hbalock); (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_irqsave() just like other callsite. Signed-off-by: Chengfeng Ye <dg573847474@gmail.com> --- drivers/scsi/lpfc/lpfc_els.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)