linux-kernel - Re: [PATCH 1/2] soc: fsl: qbman: Always disable interrupts when taking cgr

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Message-ID: <ed94f05d-929d-c4dd-3b00-0fde2a1b4595@seco.com>
Date:   Fri, 31 Mar 2023 10:55:52 -0400
From:   Sean Anderson <sean.anderson@...o.com>
To:     Camelia Alexandra Groza <camelia.groza@....com>,
        Leo Li <leoyang.li@....com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Cc:     Scott Wood <oss@...error.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Roy Pledge <roy.pledge@....com>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [PATCH 1/2] soc: fsl: qbman: Always disable interrupts when
 taking cgr_lock

On 3/31/23 06:58, Camelia Alexandra Groza wrote:
>> -----Original Message-----
>> From: Sean Anderson <sean.anderson@...o.com>
>> Sent: Monday, March 27, 2023 22:29
>> To: Leo Li <leoyang.li@....com>; linuxppc-dev@...ts.ozlabs.org; linux-arm-
>> kernel@...ts.infradead.org
>> Cc: Scott Wood <oss@...error.net>; linux-kernel@...r.kernel.org; David S .
>> Miller <davem@...emloft.net>; Claudiu Manoil <claudiu.manoil@....com>;
>> Roy Pledge <roy.pledge@....com>; Vladimir Oltean
>> <vladimir.oltean@....com>; Camelia Alexandra Groza
>> <camelia.groza@....com>; Sean Anderson <sean.anderson@...o.com>
>> Subject: [PATCH 1/2] soc: fsl: qbman: Always disable interrupts when taking
>> cgr_lock
>> 
>> smp_call_function_single disables IRQs when executing the callback. To
>> prevent deadlocks, we must disable IRQs when taking cgr_lock elsewhere.
>> This is already done by qman_update_cgr and qman_delete_cgr; fix the
>> other lockers.
>> 
>> Fixes: c535e923bb97 ("soc/fsl: Introduce DPAA 1.x QMan device driver")
>> Signed-off-by: Sean Anderson <sean.anderson@...o.com>
>> ---
>> 
>>  drivers/soc/fsl/qbman/qman.c | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/drivers/soc/fsl/qbman/qman.c b/drivers/soc/fsl/qbman/qman.c
>> index 739e4eee6b75..ff870ca07596 100644
>> --- a/drivers/soc/fsl/qbman/qman.c
>> +++ b/drivers/soc/fsl/qbman/qman.c
>> @@ -1456,7 +1456,7 @@ static void qm_congestion_task(struct work_struct
>> *work)
>>  	union qm_mc_result *mcr;
>>  	struct qman_cgr *cgr;
>> 
>> -	spin_lock(&p->cgr_lock);
>> +	spin_lock_irq(&p->cgr_lock);
>>  	qm_mc_start(&p->p);
>>  	qm_mc_commit(&p->p, QM_MCC_VERB_QUERYCONGESTION);
>>  	if (!qm_mc_result_timeout(&p->p, &mcr)) {
>> @@ -1476,7 +1476,7 @@ static void qm_congestion_task(struct work_struct
>> *work)
>>  	list_for_each_entry(cgr, &p->cgr_cbs, node)
>>  		if (cgr->cb && qman_cgrs_get(&c, cgr->cgrid))
>>  			cgr->cb(p, cgr, qman_cgrs_get(&rr, cgr->cgrid));
>> -	spin_unlock(&p->cgr_lock);
>> +	spin_unlock_irq(&p->cgr_lock);
>>  	qman_p_irqsource_add(p, QM_PIRQ_CSCI);
>>  }
> 
> There is one more spin_unlock call in qm_congestion_task on the error path that needs updating:
> 
> if (!qm_mc_result_timeout(&p->p, &mcr)) {
> 	spin_unlock(&p->cgr_lock);

Will fix. Thanks.

--Sean

> 
>> @@ -2440,7 +2440,7 @@ int qman_create_cgr(struct qman_cgr *cgr, u32
>> flags,
>>  	preempt_enable();
>> 
>>  	cgr->chan = p->config->channel;
>> -	spin_lock(&p->cgr_lock);
>> +	spin_lock_irq(&p->cgr_lock);
>> 
>>  	if (opts) {
>>  		struct qm_mcc_initcgr local_opts = *opts;
>> @@ -2477,7 +2477,7 @@ int qman_create_cgr(struct qman_cgr *cgr, u32
>> flags,
>>  	    qman_cgrs_get(&p->cgrs[1], cgr->cgrid))
>>  		cgr->cb(p, cgr, 1);
>>  out:
>> -	spin_unlock(&p->cgr_lock);
>> +	spin_unlock_irq(&p->cgr_lock);
>>  	put_affine_portal();
>>  	return ret;
>>  }
>> --
>> 2.35.1.1320.gc452695387.dirty
>