On Sun, Jan 23, 2022 at 11:40:01AM +0100, Helge Deller wrote: > On all kernels 5.15.x and 5.16.x I noticed that resetting > the USB devices with this shell script: > > for i in $(ls /sys/bus/pci/drivers/ahci/|grep :) > do > echo $i > echo $i >/sys/bus/pci/drivers/ahci/unbind > sleep 1 > echo $i >/sys/bus/pci/drivers/ahci/bind > done That is dangerous to do, why do this? All of your block devices might have disappeard. > # reseting USB3 ports (if there none you'll get errors) > for i in $(ls /sys/bus/pci/drivers/xhci_hcd/|grep :) > do > echo $i > echo $i >/sys/bus/pci/drivers/xhci_hcd/unbind > sleep 1 > echo $i >/sys/bus/pci/drivers/xhci_hcd/bind > done Again, why do this at all? > immediately leads to a non-functional system, because the discs > face I/O errors and will switch to read-only mode. Sure, the disks are gone, this is expected. > Effectively I have to reboot the machine. I'm amazed it keeps working at all. > It's reproduceable for me on two completely different x86 machines with > different USB devices. What do you expect this to do instead? You just disabled all block controllers in your system, followed by all USB controllers. And then attempted to add them back, but given that the old devices still had userspace references on them, the devices will come back with different names and so you need to mount them again. So this looks like it is working as intended. Just don't do this :) greg k-h
