On Wed, 15 Mar 2006, Paul Fulghum wrote: > On Wed, 2006-03-15 at 11:56 -0500, Alan Stern wrote: > > > Should driver core defer sysfs_remove_file until > > > last dev->kobj reference is dropped? > > > > No. The files should be deleted. James Bottomley refers to this as > > "removing from visibility". There's no point leaving the symlink visible > > once it can no longer be used. > > > > Instead, the code should be fixed so that the attempt to remove the > > already-deleted symlink by class_device_del() doesn't cause an oops. > > So dev->kobj->dentry should be set to NULL in > device_remove_file() and other code should be > fixed to check for dev->kobj->dentry == NULL ?
I don't know. I'm not familiar with the details of how sysfs is supposed to work. Maybe the existence of the symlink should prevent the dentry from being freed during sysfs_remove_dir. Or maybe sysfs_remove_dir should modify the symlink data structure so that the other code would not even try to look at dev->kobj->dentry. (It wouldn't be a bad idea to set dev->kobj->dentry to NULL as soon as the dentry is deallocated anyway. Doing that would make bugs a little easier to spot.) You know, another possibility is that cdc_acm should call tty_unregister_device as soon as the USB device is disconnected. It would make sense; no point leaving a tty visible in sysfs if it's no longer accessible (except through already-opened file descriptors). However I don't know whether the tty subsystem is designed to work that way. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
