Re: [PATCH v5 3/7] watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait context'

From: Guenter Roeck <linux@roeck-us.net>
To: Biju Das <biju.das.jz@bp.renesas.com>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>,
	linux-watchdog@vger.kernel.org,
	Linux PM list <linux-pm@vger.kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Chris Paterson <Chris.Paterson2@renesas.com>,
	Biju Das <biju.das@bp.renesas.com>,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH v5 3/7] watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait context'
Date: Fri, 25 Feb 2022 12:18:00 -0800	[thread overview]
Message-ID: <20220225201800.GB2900426@roeck-us.net> (raw)
In-Reply-To: <20220225175320.11041-4-biju.das.jz@bp.renesas.com>

On Fri, Feb 25, 2022 at 05:53:16PM +0000, Biju Das wrote:
> This patch fixes the issue 'BUG: Invalid wait context' during restart()
> callback by using clk_prepare_enable() instead of pm_runtime_get_sync()
> for turning on the clocks during restart.
> 
> This issue is noticed when testing with renesas_defconfig.
> 
> [   42.213802] reboot: Restarting system
> [   42.217860]
> [   42.219364] =============================
> [   42.223368] [ BUG: Invalid wait context ]
> [   42.227372] 5.17.0-rc5-arm64-renesas-00002-g10393723e35e #522 Not tainted
> [   42.234153] -----------------------------
> [   42.238155] systemd-shutdow/1 is trying to lock:
> [   42.242766] ffff00000a650828 (&genpd->mlock){+.+.}-{3:3}, at: genpd_lock_mtx+0x14/0x20
> [   42.250709] other info that might help us debug this:
> [   42.255753] context-{4:4}
> [   42.258368] 2 locks held by systemd-shutdow/1:
> [   42.262806]  #0: ffff80000944e1c8 (system_transition_mutex#2){+.+.}-{3:3}, at: __do_sys_reboot+0xd0/0x250
> [   42.272388]  #1: ffff8000094c4e40 (rcu_read_lock){....}-{1:2}, at: atomic_notifier_call_chain+0x0/0x150
> [   42.281795] stack backtrace:
> [   42.284672] CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 5.17.0-rc5-arm64-renesas-00002-g10393723e35e #522
> [   42.294577] Hardware name: Renesas SMARC EVK based on r9a07g044c2 (DT)
> [   42.301096] Call trace:
> [   42.303538]  dump_backtrace+0xcc/0xd8
> [   42.307203]  show_stack+0x14/0x30
> [   42.310517]  dump_stack_lvl+0x88/0xb0
> [   42.314180]  dump_stack+0x14/0x2c
> [   42.317492]  __lock_acquire+0x1b24/0x1b50
> [   42.321502]  lock_acquire+0x120/0x3a8
> [   42.325162]  __mutex_lock+0x84/0x8f8
> [   42.328737]  mutex_lock_nested+0x30/0x58
> [   42.332658]  genpd_lock_mtx+0x14/0x20
> [   42.336319]  genpd_runtime_resume+0xc4/0x228
> [   42.340587]  __rpm_callback+0x44/0x170
> [   42.344337]  rpm_callback+0x64/0x70
> [   42.347824]  rpm_resume+0x4e0/0x6b8
> [   42.351310]  __pm_runtime_resume+0x50/0x78
> [   42.355404]  rzg2l_wdt_restart+0x28/0x68
> [   42.359329]  watchdog_restart_notifier+0x1c/0x30
> [   42.363943]  atomic_notifier_call_chain+0x94/0x150
> [   42.368732]  do_kernel_restart+0x24/0x30
> [   42.372652]  machine_restart+0x44/0x70
> [   42.376399]  kernel_restart+0x3c/0x60
> [   42.380058]  __do_sys_reboot+0x228/0x250
> [   42.383977]  __arm64_sys_reboot+0x20/0x28
> [   42.387983]  invoke_syscall+0x40/0xf8
> 
> Fixes: 2cbc5cd0b55fa2 ("watchdog: Add Watchdog Timer driver for RZ/G2L")
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> V4->V5:
>  * Added Rb tag from Geert.
>  * CC'ed Linux PM.
> V4:
>  * New patch
> ---
>  drivers/watchdog/rzg2l_wdt.c | 25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
> index 0fc73b8a9567..48dfe6e5e64f 100644
> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c
> @@ -43,6 +43,8 @@ struct rzg2l_wdt_priv {
>  	struct reset_control *rstc;
>  	unsigned long osc_clk_rate;
>  	unsigned long delay;
> +	struct clk *pclk;
> +	struct clk *osc_clk;
>  };
>  
>  static void rzg2l_wdt_wait_delay(struct rzg2l_wdt_priv *priv)
> @@ -118,7 +120,9 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev,
>  
>  	/* Reset the module before we modify any register */
>  	reset_control_reset(priv->rstc);
> -	pm_runtime_get_sync(wdev->parent);
> +
> +	clk_prepare_enable(priv->pclk);
> +	clk_prepare_enable(priv->osc_clk);
>  
>  	/* smallest counter value to reboot soon */
>  	rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(1), WDTSET);
> @@ -165,7 +169,6 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct rzg2l_wdt_priv *priv;
>  	unsigned long pclk_rate;
> -	struct clk *wdt_clk;
>  	int ret;
>  
>  	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> @@ -177,22 +180,20 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>  		return PTR_ERR(priv->base);
>  
>  	/* Get watchdog main clock */
> -	wdt_clk = clk_get(&pdev->dev, "oscclk");
> -	if (IS_ERR(wdt_clk))
> -		return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no oscclk");
> +	priv->osc_clk = devm_clk_get(&pdev->dev, "oscclk");
> +	if (IS_ERR(priv->osc_clk))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(priv->osc_clk), "no oscclk");
>  
> -	priv->osc_clk_rate = clk_get_rate(wdt_clk);
> -	clk_put(wdt_clk);
> +	priv->osc_clk_rate = clk_get_rate(priv->osc_clk);
>  	if (!priv->osc_clk_rate)
>  		return dev_err_probe(&pdev->dev, -EINVAL, "oscclk rate is 0");
>  
>  	/* Get Peripheral clock */
> -	wdt_clk = clk_get(&pdev->dev, "pclk");
> -	if (IS_ERR(wdt_clk))
> -		return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no pclk");
> +	priv->pclk = devm_clk_get(&pdev->dev, "pclk");
> +	if (IS_ERR(priv->pclk))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(priv->pclk), "no pclk");
>  
> -	pclk_rate = clk_get_rate(wdt_clk);
> -	clk_put(wdt_clk);
> +	pclk_rate = clk_get_rate(priv->pclk);
>  	if (!pclk_rate)
>  		return dev_err_probe(&pdev->dev, -EINVAL, "pclk rate is 0");
>  
> -- 
> 2.17.1
>