Messages in this thread | | | Subject | Re: [PATCH v3 1/4] remoteproc: core: Move cdev add before device add | From | Siddharth Gupta <> | Date | Tue, 15 Jun 2021 12:03:26 -0700 |
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On 6/14/2021 9:56 PM, Greg KH wrote: > On Mon, Jun 14, 2021 at 07:21:08PM -0700, Siddharth Gupta wrote: >> When cdev_add is called after device_add has been called there is no >> way for the userspace to know about the addition of a cdev as cdev_add >> itself doesn't trigger a uevent notification, or for the kernel to >> know about the change to devt. This results in two problems: >> - mknod is never called for the cdev and hence no cdev appears on >> devtmpfs. >> - sysfs links to the new cdev are not established. >> >> The cdev needs to be added and devt assigned before device_add() is >> called in order for the relevant sysfs and devtmpfs entries to be >> created and the uevent to be properly populated. > So this means no one ever ran this code on a system that used devtmpfs? > > How was it ever tested? My testing was done with toybox + Android's ueventd ramdisk. As I mentioned in the discussion, the race became evident recently. I will make sure to test all such changes without systemd/ueventd in the future.
Thanks, Sid
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