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

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Message-ID: <AM6PR04MB57997C946E6AE7F2D87B5C78F28F9@AM6PR04MB5799.eurprd04.prod.outlook.com>
Date:   Fri, 31 Mar 2023 10:58:44 +0000
From:   Camelia Alexandra Groza <camelia.groza@....com>
To:     Sean Anderson <sean.anderson@...o.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>,
        Sean Anderson <sean.anderson@...o.com>
Subject: RE: [PATCH 1/2] soc: fsl: qbman: Always disable interrupts when
 taking cgr_lock

> -----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);

Regards,
Camelia

> @@ -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