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Subject: Re: [qla2xxx] INFO: possible irq lock inversion dependency detected
From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Jiri Kosina <jkosina@suse.cz>, linux-scsi@vger.kernel.org,
        James.Bottomley@hansenpartnership.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        target-devel <target-devel@vger.kernel.org>,
        Andrew Vasquez <andrew.vasquez@qlogic.com>,
        Chad Dupuis <chad.dupuis@qlogic.com>,
        Giridhar Malavali <giridhar.malavali@qlogic.com>
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Date: Thu, 04 Oct 2012 11:44:15 -0700
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On Thu, 2012-10-04 at 21:11 +0530, Srivatsa S. Bhat wrote:
> Hi Jiri,
> 
> Thanks for taking a look!

Hi Srivatsa & Jiri,

>  
> > This seems to be real. You should be seeing that since 3.5-rc1 already 
> > though ... ?
> > 
> > Does the patch below fix that?
> > 
> 
> Yes, it does, thanks! But 3.6-rc kernels were booting fine as far as I remember.
> I'll check again and get back tomorrow.
> 

Thanks for testing with v3.7-rc0 code !

Cc'ing the Qlogic folks here, as this irq lock inversion warning appears
to be regression from v3.7-rc1 qla2xxx (initiator) LLD changes that went
in recently via scsi.git.

Thanks,

--nab

> > 
> > From: Jiri Kosina <jkosina@suse.cz>
> > Subject: [PATCH] [SCSI] qla2xxx: fix potential deadlock on ha->hardware_lock
> > 
> > Lockdep reports:
> > 
> > === [ cut here ] ===
> >  =========================================================
> >  [ INFO: possible irq lock inversion dependency detected ]
> >  3.6.0-0.0.0.28.36b5ec9-default #1 Not tainted
> >  ---------------------------------------------------------
> >  qla2xxx_1_dpc/368 just changed the state of lock:
> >   (&(&ha->vport_slock)->rlock){+.....}, at: [<ffffffffa009b377>] qla2x00_configure_hba+0x197/0x3c0 [qla2xxx]
> >  but this lock was taken by another, HARDIRQ-safe lock in the past:
> >   (&(&ha->hardware_lock)->rlock){-.....}
> > 
> > and interrupts could create inverse lock ordering between them.
> > 
> > other info that might help us debug this:
> >  Possible interrupt unsafe locking scenario:
> > 
> >        CPU0                    CPU1
> >        ----                    ----
> >   lock(&(&ha->vport_slock)->rlock);
> >                                local_irq_disable();
> >                                lock(&(&ha->hardware_lock)->rlock);
> >                                lock(&(&ha->vport_slock)->rlock);
> >   <Interrupt>
> >     lock(&(&ha->hardware_lock)->rlock);
> > === [ cut here ] ===
> > 
> > Fix the potential deadlock by disabling IRQs while holding ha->vport_slock.
> > 
> > Reported-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> > Signed-off-by: Jiri Kosina <jkosina@suse.cz>
> 
> Tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> 
> Regards,
> Srivatsa S. Bhat
> 
> > ---
> >  drivers/scsi/qla2xxx/qla_init.c |    5 +++--
> >  1 files changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
> > index 799a58b..48fca47 100644
> > --- a/drivers/scsi/qla2xxx/qla_init.c
> > +++ b/drivers/scsi/qla2xxx/qla_init.c
> > @@ -2080,6 +2080,7 @@ qla2x00_configure_hba(scsi_qla_host_t *vha)
> >  	uint8_t       domain;
> >  	char		connect_type[22];
> >  	struct qla_hw_data *ha = vha->hw;
> > +	unsigned long flags;
> > 
> >  	/* Get host addresses. */
> >  	rval = qla2x00_get_adapter_id(vha,
> > @@ -2154,9 +2155,9 @@ qla2x00_configure_hba(scsi_qla_host_t *vha)
> >  	vha->d_id.b.area = area;
> >  	vha->d_id.b.al_pa = al_pa;
> > 
> > -	spin_lock(&ha->vport_slock);
> > +	spin_lock_irqsave(&ha->vport_slock, flags);
> >  	qlt_update_vp_map(vha, SET_AL_PA);
> > -	spin_unlock(&ha->vport_slock);
> > +	spin_unlock_irqrestore(&ha->vport_slock, flags);
> > 
> >  	if (!vha->flags.init_done)
> >  		ql_log(ql_log_info, vha, 0x2010,
> > 
> 
> --
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