FUJITA Tomonori wrote: >> Besides holding the lock during kref_put(), I also considered two >> other simple ways to avoid this race: >> 1) Do idr_remove() from sg_remove(). >> 2) Return NULL in sg_get_dev() if sdp->detached. >> >> However, both of these options would have changed the behavior of >> the /proc/scsi/sg/* functions that show information for devices that >> are in the process of being detached. I wanted to fix bugs without >> changing other behavior, so I chose to call kref_put() under lock in >> my previous patches. >> > > How about doing 2) and accessing to /proc/scsi/sg/* with > sg_index_lock (don't use sg_get_device for it). > > That's an excellent idea. If it works, I can forget this whole atomic_inc_not_zero() business and the pain that goes with it. > What /proc/scsi/sg/* doing is abnormal from the perspective of the ref > counting (accessing to something that is going away). > > >From the perspective of the ref counting, the best way is calling > idr_remove in from sg_remove but as you said, it's not nice to change > the behavior. > > Exactly. > If we don't use sg_get_device for /proc/scsi/sg/*, then we use > sg_get_device for only sg_open So we can do 2) without changing the > behavior. > > I will try to implement it this way today. Thanks for your input. Tony -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
