From: Aisheng Dong <aisheng.dong@nxp.com>
To: Anson Huang <anson.huang@nxp.com>,
"a.zummo@towertech.it" <a.zummo@towertech.it>,
"alexandre.belloni@bootlin.com" <alexandre.belloni@bootlin.com>,
"linux-rtc@vger.kernel.org" <linux-rtc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: dl-linux-imx <linux-imx@nxp.com>
Subject: RE: [PATCH] rtc: snvs: fix possible race condition
Date: Wed, 17 Jul 2019 10:54:06 +0000 [thread overview]
Message-ID: <AM0PR04MB421167283C950557E231181480C90@AM0PR04MB4211.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20190716071858.36750-1-Anson.Huang@nxp.com>
> From: Anson.Huang@nxp.com <Anson.Huang@nxp.com>
> Sent: Tuesday, July 16, 2019 3:19 PM
>
> The RTC IRQ is requested before the struct rtc_device is allocated, this may
> lead to a NULL pointer dereference in IRQ handler.
>
> To fix this issue, allocating the rtc_device struct before requesting the RTC IRQ
> using devm_rtc_allocate_device, and use rtc_register_device to register the
> RTC device.
>
I saw other rtc drivers did the same way as us, so this looks like a common problem.
My question is if we can clear interrupt status before register to avoid this issue as
other rtc drivers?
Regards
Aisheng
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> ---
> drivers/rtc/rtc-snvs.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c index
> 7ee673a2..4f9a107 100644
> --- a/drivers/rtc/rtc-snvs.c
> +++ b/drivers/rtc/rtc-snvs.c
> @@ -279,6 +279,10 @@ static int snvs_rtc_probe(struct platform_device
> *pdev)
> if (!data)
> return -ENOMEM;
>
> + data->rtc = devm_rtc_allocate_device(&pdev->dev);
> + if (IS_ERR(data->rtc))
> + return PTR_ERR(data->rtc);
> +
> data->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
> "regmap");
>
> if (IS_ERR(data->regmap)) {
> @@ -343,10 +347,9 @@ static int snvs_rtc_probe(struct platform_device
> *pdev)
> goto error_rtc_device_register;
> }
>
> - data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
> - &snvs_rtc_ops, THIS_MODULE);
> - if (IS_ERR(data->rtc)) {
> - ret = PTR_ERR(data->rtc);
> + data->rtc->ops = &snvs_rtc_ops;
> + ret = rtc_register_device(data->rtc);
> + if (ret) {
> dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
> goto error_rtc_device_register;
> }
> --
> 2.7.4
next prev parent reply other threads:[~2019-07-17 10:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-16 7:18 [PATCH] rtc: snvs: fix possible race condition Anson.Huang
2019-07-17 10:54 ` Aisheng Dong [this message]
2019-07-17 13:57 ` Anson Huang
2019-07-18 3:08 ` Aisheng Dong
2019-07-18 16:32 ` Trent Piepho
2019-07-19 2:57 ` Anson Huang
2019-07-19 19:04 ` Trent Piepho
2019-07-20 19:55 ` Alexandre Belloni
2019-08-13 9:22 ` Anson Huang
2019-08-29 15:39 ` Alexandre Belloni
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