Hi Dominique, On 2018/8/8 16:36, Dominique Martinet wrote: > piaojun wrote on Wed, Aug 08, 2018: >> I found that 9pnet_virtio.ko could not be removed by rmmod command, and I >> could still found it by lsmod. The reason is that we forgot decrease the >> refcount of 9p virtio device by kobject_put. So we should put refcount in >> p9_virtio_remove. > > > Hmm, I cannot seem to reproduce this. Can you give more details on how > to get into stuck state? > I tried mounting something, accessing the sysfs files, etc to no avail. > > lsmod gives a counter to how many references there are to the module, > you can use that to debug a bit. > For example here I get this line just after loading the module: > 9pnet_virtio 32768 0 > > Then after mounting something there is one reference: > 9pnet_virtio 32768 1 > > Then unmounting puts that back to 0 and 'modprobe -r' (or rmmod) works. > I try to remove 9pnet_virtio.ko by 'rmmod 9pnet_virtio' as I want to replace it without rebooting system. Here I have not mount 9pfs yet, so the refcount is still 0.
Before rmmod: # lsmod | grep 9p 9pnet_virtio 20480 0 9pnet 106496 1 9pnet_virtio virtio_ring 28672 5 virtio_scsi,9pnet_virtio,virtio_pci,virtio_blk,virtio_net virtio 16384 5 virtio_scsi,9pnet_virtio,virtio_pci,virtio_blk,virtio_net After rmmod: # lsmod | grep 9p 9pnet_virtio 20480 0 9pnet 106496 1 9pnet_virtio virtio_ring 28672 5 virtio_scsi,9pnet_virtio,virtio_pci,virtio_blk,virtio_net virtio 16384 5 virtio_scsi,9pnet_virtio,virtio_pci,virtio_blk,virtio_net Normally 9pnet_virtio should be invisible after rmmod like this: # lsmod | grep 9p 9pnet 106496 0 > > > > I dislike saying the next part but I think form also is important, > please bear with me: > > - shorter subject line, please. For example, you can lose 20 characters > by reodering words so there is no need for pronouns > "net/9p/virtio: decrease 9p virtio device refcount on removal" > > - I personally dislike commit messages that are "novelized" (that is, > put yourself as an actor and describe what you were doing) > That seems to be somewhat accepted as looking at the kernel's git log I > see some (few) commits using "I ..." that are not pull request messages > but if possible please avoid this style and try to describe facts, how > things are wrong, what got fixed and if required how. > To give an example again, this says the same thing: > "The 9pnet_virtio module could not be unloaded because we forgot to > decrease the refcount of the 9p virtio device with kobject_put. > > Put the reference in 9p_virtio_remove" > Your suggestion really makes sense, and I will make some improvment later. Thanks, Jun > > Thanks, >
