On Fri, Dec 08, 2023 at 03:41:59PM -0400, Jason Gunthorpe wrote: > On Fri, Dec 08, 2023 at 05:07:22PM +0000, Jim Harris wrote: > > > > Maybe for now we just whack this specific mole with a separate mutex > > for synchronizing access to sriov->num_VFs in the sysfs paths? > > Something like this (tested on my system): > > TBH, I don't have the time right now to unpack this locking > mystery. Maybe Leon remembers? > > device_lock() gets everywhere and does a lot of different stuff, so I > would be surprised if it was so easy.. The store() side still keeps the device_lock(), it just also acquires this new sriov lock. So store() side should observe zero differences. The only difference is now the show() side can acquire just the more-granular lock, since it is only trying to synchronize on sriov->num_VFs with the store() side. But maybe I'm missing something subtle here... Adding Pierre who authored the 35ff867b7 commit.
