linux-kernel - Re: [PATCH] [RESEND] qla2xxx: fix potential deadlock on ha->hardware

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Date:	Tue, 9 Oct 2012 12:56:06 -0700
From:	Arun Easi <arun.easi@...gic.com>
To:	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>
CC:	Jiri Kosina <jkosina@...e.cz>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	Dept-Eng Linux Driver <Linux-Driver@...gic.com>,
	Andrew Vasquez <andrew.vasquez@...gic.com>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Saurav Kashyap <saurav.kashyap@...gic.com>,
	target-devel <target-devel@...r.kernel.org>,
	Roland Dreier <roland@...nel.org>
Subject: Re: [PATCH] [RESEND] qla2xxx: fix potential deadlock on
 ha->hardware_lock

Hi Nick,

On Tue, 9 Oct 2012, 11:47am -0700, Nicholas A. Bellinger wrote:

> Hi Jiri, Andrew, Arun & Co,
>
--8<-- snipped --
>
> Also please have a look below for a few more related items I noticed
> while reviewing this patch..
>
>>  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,
>>
>
> So while looking at other ->vport_slock + qlt_update_vp_map() usage, two
> more items caught my eye:
>
> In qla_mid.c:qla24xx_disable_vp() code:
>
>        ret = qla24xx_control_vp(vha, VCE_COMMAND_DISABLE_VPS_LOGO_ALL);
>        atomic_set(&vha->loop_state, LOOP_DOWN);
>        atomic_set(&vha->loop_down_timer, LOOP_DOWN_TIME);
>
>        /* Remove port id from vp target map */
>        qlt_update_vp_map(vha, RESET_AL_PA);
>
>        qla2x00_mark_vp_devices_dead(vha);
>        atomic_set(&vha->vp_state, VP_FAILED);
>
> AFAICT all callers of qlt_update_vp_map() into qla_target.c code should
> be holding ->vport_slock.  I'll send out a separate patch for this
> shortly.

Makes sense.

>
> And in qla_init.c:qla2x00_init_rings() code:
>
>        for (que = 0; que < ha->max_rsp_queues; que++) {
>                rsp = ha->rsp_q_map[que];
>                if (!rsp)
>                        continue;
>                /* Initialize response queue entries */
>                qla2x00_init_response_q_entries(rsp);
>        }
>
>        spin_lock(&ha->vport_slock);
>
>        spin_unlock(&ha->vport_slock);
>
>        ha->tgt.atio_ring_ptr = ha->tgt.atio_ring;
>        ha->tgt.atio_ring_index = 0;
>        /* Initialize ATIO queue entries */
>        qlt_init_atio_q_entries(vha);
>
> The usage of ->vport_slock seems to be now either unnecessary, or a
> result of some bad merge outside of qla2xxx target mode.
>
> Qlogic folks, can this (leftover..?) usage of ->vport_slock now be
> safety removed..?
>

Yes, this is a left over of code removal and can be safely removed. We
already have a patch queued internally for this.

--Arun

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