On Fri, 16 Feb 2018 10:06:49 +0100, Lorenzo Bianconi wrote: > > Hm.. There should be no path in the driver where that could cause > > problems AFAIR. We have reg_atomic_mutex and hw_atomic_mutex to > > protect from concurrent access to the HW where they are possible. > > RMW operations are non-atomic by definition, it's supposed to work > > like PCIe register accesses would - 32bit reads/writes are atomic, > > but RMW is not. > > Yes, RMW accesses are non-atomic by default but since vendor_req_mutex mutex > is already there (and grabbed for RMW operations), why not use it to make > write > with mask access atomic without adding complexity? Moreover it would be a > micro-optimisation since vendor_req_mutex would be grabbed just once instead > of > twice > > > > > So I'm not sure what to do with this patch. Doesn't seem necessary... > > It is just a trivial rework of locking in usb read/write accesses, not > mandatory, so if you prefer we can just drop it
You make good points :) Could you please respin stating clearly in the commit message that this is not a bug fix, but a micro-optimization and may be useful in the future?
