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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

14
drivers/rtc/class.c
View File

@@ -195,6 +195,8 @@ struct rtc_device *rtc_device_register(const char *name, struct device *dev,
goto exit_ida;
}
device_initialize(&rtc->dev);
rtc->id = id;
rtc->ops = ops;
rtc->owner = owner;
@@ -233,14 +235,19 @@ struct rtc_device *rtc_device_register(const char *name, struct device *dev,
rtc_dev_prepare(rtc);
err = device_register(&rtc->dev);
err = cdev_device_add(&rtc->char_dev, &rtc->dev);
if (err) {
dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
rtc->name, MAJOR(rtc->dev.devt), rtc->id);
/* This will free both memory and the ID */
put_device(&rtc->dev);
goto exit;
} else {
dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", rtc->name,
MAJOR(rtc->dev.devt), rtc->id);
}
rtc_dev_add_device(rtc);
rtc_proc_add_device(rtc);
dev_info(dev, "rtc core: registered %s as %s\n",
@@ -271,9 +278,8 @@ void rtc_device_unregister(struct rtc_device *rtc)
* Remove innards of this RTC, then disable it, before
* letting any rtc_class_open() users access it again
*/
rtc_dev_del_device(rtc);
rtc_proc_del_device(rtc);
device_del(&rtc->dev);
cdev_device_del(&rtc->char_dev, &rtc->dev);
rtc->ops = NULL;
mutex_unlock(&rtc->ops_lock);
put_device(&rtc->dev);