From: geert@linux-m68k.org (Geert Uytterhoeven)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] Initial support for Allwinner's Security ID fuses
Date: Wed, 26 Jun 2013 11:22:30 +0200 [thread overview]
Message-ID: <CAMuHMdVkyTXDsEyAvD4pHBiXHADbncGUHeeqXBCQMbU7t6TTDQ@mail.gmail.com> (raw)
In-Reply-To: <20130624160440.GA15201@kroah.com>
On Mon, Jun 24, 2013 at 6:04 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Mon, Jun 24, 2013 at 11:29:42AM +0200, Maxime Ripard wrote:
>> On Mon, Jun 17, 2013 at 03:58:47PM -0700, Greg KH wrote:
>> > On Mon, Jun 17, 2013 at 10:59:37PM +0200, Oliver Schinagl wrote:
>> > > +static int __init sunxi_sid_probe(struct platform_device *pdev)
>> > > +{
>> > > + u8 entropy[SID_SIZE];
>> > > + unsigned int i;
>> > > + struct resource *res;
>> > > + void __iomem *sid_reg_base;
>> > > + int ret;
>> > > +
>> > > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> > > + sid_reg_base = devm_ioremap_resource(&pdev->dev, res);
>> > > + if (IS_ERR(sid_reg_base))
>> > > + return PTR_ERR(sid_reg_base);
>> > > + platform_set_drvdata(pdev, sid_reg_base);
>> > > +
>> > > + ret = device_create_bin_file(&pdev->dev, &sid_bin_attr);
>> > > + if (ret)
>> > > + return ret;
>> >
>> > You just raced with userspace, having the file show up after the device
>> > was announced to users that it was there. Please use the proper device
>> > file api to add default attributes to prevent this from happening.
>>
>> Sorry if the question looks dumb, but what kind of race can we generate
>> here?
>
> Userspace gets told about the device from the driver core, udev runs and
> reads all of the attributes, then your probe function comes along and
> adds a new attribute. Userspace will then not know about it at all.
>
>> The device_create_bin_file is the last call that we make (if we except
>> the entropy stuff, but it doesn't really matter here), so after we
>> created the file, we have everything properly initialised so that our
>> functions can be called, right?
>>
>> And another dumb question for you, what is the "proper device file API"
>> you are referring to ? :)
>
> Please read Documentation/driver_model/device.txt and see the section on
> Attributes for what to do. If you have specific questions after reading
> that, please let me know.
Woops, then we have plenty of existing drivers to fix, e.g. all/most RTC drivers
exposing an NVRAM file through sysfs:
$ git grep -w sysfs_create_bin_file drivers/rtc/
drivers/rtc/rtc-cmos.c: retval = sysfs_create_bin_file(&dev->kobj, &nvram);
drivers/rtc/rtc-ds1305.c: status =
sysfs_create_bin_file(&spi->dev.kobj, &nvram);
drivers/rtc/rtc-ds1307.c: err =
sysfs_create_bin_file(&client->dev.kobj, ds1307->nvram);
drivers/rtc/rtc-ds1511.c: ret = sysfs_create_bin_file(&pdev->dev.kobj,
&ds1511_nvram_attr);
drivers/rtc/rtc-ds1553.c: ret = sysfs_create_bin_file(&pdev->dev.kobj,
&ds1553_nvram_attr);
drivers/rtc/rtc-ds1742.c: ret = sysfs_create_bin_file(&pdev->dev.kobj,
&pdata->nvram_attr);
drivers/rtc/rtc-m48t59.c: ret = sysfs_create_bin_file(&pdev->dev.kobj,
&m48t59_nvram_attr);
drivers/rtc/rtc-rp5c01.c: error =
sysfs_create_bin_file(&dev->dev.kobj, &priv->nvram_attr);
drivers/rtc/rtc-stk17ta8.c: ret =
sysfs_create_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
drivers/rtc/rtc-tx4939.c: ret = sysfs_create_bin_file(&pdev->dev.kobj,
&tx4939_rtc_nvram_attr);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2013-06-26 9:22 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-17 20:59 [PATCH 0/2] v4 Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-06-17 20:59 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-06-17 21:06 ` Tomasz Figa
2013-06-17 22:58 ` Greg KH
2013-06-17 23:23 ` [linux-sunxi] " Henrik Nordström
2013-06-24 9:29 ` Maxime Ripard
2013-06-24 16:04 ` Greg KH
2013-06-24 17:11 ` Oliver Schinagl
2013-06-24 18:15 ` Greg KH
2013-06-24 21:21 ` Oliver Schinagl
2013-06-24 21:46 ` Greg KH
2013-06-26 8:32 ` Oliver Schinagl
2013-06-26 17:51 ` Greg KH
2013-07-05 7:24 ` Oliver Schinagl
2013-07-06 19:36 ` Greg KH
2013-07-07 0:17 ` Greg KH
2013-07-15 21:16 ` [linux-sunxi] " Oliver Schinagl
2013-07-16 6:41 ` Greg KH
2013-07-16 21:02 ` Oliver Schinagl
2013-07-17 4:20 ` Greg KH
2013-07-17 11:46 ` Maxime Ripard
2013-07-17 16:17 ` Greg KH
2013-07-19 9:42 ` Maxime Ripard
2013-07-19 23:49 ` Greg KH
2013-07-30 13:22 ` Oliver Schinagl
2013-07-30 14:20 ` Greg KH
2013-07-30 17:39 ` Oliver Schinagl
2013-06-26 9:10 ` Russell King - ARM Linux
2013-06-26 17:51 ` Greg KH
2013-06-24 21:04 ` Maxime Ripard
2013-06-26 9:22 ` Geert Uytterhoeven [this message]
2013-06-26 17:49 ` Greg KH
2013-06-18 5:41 ` Andy Shevchenko
-- strict thread matches above, loose matches on Subject: below --
2013-08-27 14:13 [PATCHv5 0/2] Driver for Allwinner sunxi Security ID oliver+list at schinagl.nl
2013-08-27 14:13 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses oliver+list at schinagl.nl
2013-08-27 15:42 ` Maxime Ripard
2013-06-14 23:16 [PATCH 0/2] v3 Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-06-14 23:16 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-06-15 2:14 ` Andy Shevchenko
2013-06-15 9:34 ` Oliver Schinagl
2013-06-15 10:28 ` Tomasz Figa
2013-06-17 10:36 ` Oliver Schinagl
2013-06-17 11:25 ` Russell King - ARM Linux
2013-06-17 11:32 ` Oliver Schinagl
2013-06-17 11:51 ` Maxime Ripard
2013-06-17 12:04 ` Oliver Schinagl
2013-06-17 12:51 ` Tomasz Figa
2013-06-17 13:10 ` Oliver Schinagl
2013-06-17 13:23 ` Tomasz Figa
2013-06-17 13:47 ` Oliver Schinagl
2013-06-02 14:58 [PATCH 0/2] v2 Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-06-02 14:58 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-06-02 15:09 ` Russell King - ARM Linux
2013-06-02 15:21 ` Oliver Schinagl
2013-06-06 19:16 ` Andy Shevchenko
2013-06-10 21:43 ` Oliver Schinagl
2013-06-11 10:51 ` Andy Shevchenko
2013-05-17 13:35 [PATCH 0/2] Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-05-17 13:35 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-05-17 13:45 ` Arnd Bergmann
2013-05-17 18:54 ` Oliver Schinagl
2013-05-17 21:18 ` Maxime Ripard
2013-05-18 17:19 ` Oliver Schinagl
2013-05-19 15:22 ` Maxime Ripard
2013-05-24 21:50 ` Oliver Schinagl
2013-05-25 12:22 ` Maxime Ripard
2013-05-25 19:25 ` Oliver Schinagl
2013-05-26 9:35 ` Maxime Ripard
2013-05-23 7:56 ` Linus Walleij
2013-05-23 8:10 ` Oliver Schinagl
2013-05-23 8:20 ` Linus Walleij
2013-05-23 14:58 ` Maxime Ripard
2013-05-23 15:05 ` Oliver Schinagl
2013-05-23 15:27 ` Maxime Ripard
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