Messages in this thread | | | Subject | Re: [PATCH v2] chardev: fix error handling in cdev_device_add() | From | Yang Yingliang <> | Date | Thu, 1 Dec 2022 20:06:44 +0800 |
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Hi Greg,
On 2022/10/25 21:37, Greg KH wrote: > On Tue, Oct 25, 2022 at 09:20:12PM +0800, Yang Yingliang wrote: >> Hi, Greg >> >> On 2022/10/25 19:50, Greg KH wrote: >>> On Tue, Oct 25, 2022 at 07:39:57PM +0800, Yang Yingliang wrote: >>>> While doing fault injection test, I got the following report: >>>> >>>> ------------[ cut here ]------------ >>>> kobject: '(null)' (0000000039956980): is not initialized, yet kobject_put() is being called. >>>> WARNING: CPU: 3 PID: 6306 at kobject_put+0x23d/0x4e0 >>>> CPU: 3 PID: 6306 Comm: 283 Tainted: G W 6.1.0-rc2-00005-g307c1086d7c9 #1253 >>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 >>>> RIP: 0010:kobject_put+0x23d/0x4e0 >>>> Call Trace: >>>> <TASK> >>>> cdev_device_add+0x15e/0x1b0 >>>> __iio_device_register+0x13b4/0x1af0 [industrialio] >>>> __devm_iio_device_register+0x22/0x90 [industrialio] >>>> max517_probe+0x3d8/0x6b4 [max517] >>>> i2c_device_probe+0xa81/0xc00 >>>> >>>> When device_add() is injected fault and returns error, if dev->devt is not set, >>>> cdev_add() is not called, cdev_del() is not needed. Fix this by checking dev->devt >>>> in error path. >>> Nit, please wrap your changelog text at 72 columns. >>> >>>> Fixes: 233ed09d7fda ("chardev: add helper function to register char devs with a struct device") >>>> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> >>>> --- >>>> v1 -> v2: >>>> Add information to update commit message. >>>> v1 link: https://lore.kernel.org/lkml/1959fa74-b06c-b8bc-d14f-b71e5c4290ee@huawei.com/T/ >>>> --- >>>> fs/char_dev.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/fs/char_dev.c b/fs/char_dev.c >>>> index ba0ded7842a7..3f667292608c 100644 >>>> --- a/fs/char_dev.c >>>> +++ b/fs/char_dev.c >>>> @@ -547,7 +547,7 @@ int cdev_device_add(struct cdev *cdev, struct device *dev) >>>> } >>>> rc = device_add(dev); >>>> - if (rc) >>>> + if (rc && dev->devt) >>> No, this is a layering violation and one that you do not know is really >>> going to be true or not. the devt being present, or not, should not be >>> an issue of if the device_add failed or not. This isn't correct, sorry. >> Do you mean it's not a bug or the warn can be ignored or it's bug in driver >> ? >> I see devt is checked before calling cdev_del() in cdev_device_del(). > Ah! The core doesn't set devt, the caller has that set. That makes > more sense now, sorry for the confusion on my side. > > Yes, this looks correct, the diff didn't have the full context and I was > confused. > > I'll go queue this up, very nice work. > > greg k-h I didn't find this patch in your trees, does it been merged?
Thanks, Yang > .
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