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rtc: utilize new cdev_device_add helper function

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Mostly straightforward, but we had to remove the rtc_dev_add/del_device
functions as they split up the cdev_add and the device_add.

Doing this also revealed that there was likely another subtle bug:
seeing cdev_add was done after device_register, the cdev probably
was not ready before device_add when the uevent occurs. This would
race with userspace, if it tried to use the device directly after
the uevent. This is fixed just by using the new helper function.

Another weird thing is this driver would, in some error cases, call
cdev_add() without calling cdev_init. This patchset corrects this
by avoiding calling cdev_add if the devt is not set.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Logan Gunthorpe 2017-03-17 12:48:21 -06:00 • committed by Greg Kroah-Hartman
parent dbef390d2e
commit d5ed9177f6
3 changed files with 10 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

17
drivers/rtc/rtc-dev.c
View file

@ -477,23 +477,6 @@ void rtc_dev_prepare(struct rtc_device *rtc)
cdev_init(&rtc->char_dev, &rtc_dev_fops);
rtc->char_dev.owner = rtc->owner;
rtc->char_dev.kobj.parent = &rtc->dev.kobj;
}
void rtc_dev_add_device(struct rtc_device *rtc)
{
if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
rtc->name, MAJOR(rtc_devt), rtc->id);
else
dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", rtc->name,
MAJOR(rtc_devt), rtc->id);
}
void rtc_dev_del_device(struct rtc_device *rtc)
{
if (rtc->dev.devt)
cdev_del(&rtc->char_dev);
}
void __init rtc_dev_init(void)