On Tue, Nov 29, 2022 at 03:38:33PM -0800, Paul E. McKenney wrote: > On Tue, Nov 29, 2022 at 04:58:21PM +0100, Uladzislau Rezki (Sony) wrote: > > Currently a need_offload_krc() function requires the krcp->lock > > to be held because krcp->head can not be checked concurrently. > > > > Fix it by updating the krcp->head using WRITE_ONCE() macro so > > it becomes lock-free and safe for readers to see a valid data > > without any locking. > > Don't we also need to use READ_ONCE() for the code loading this krcp->head > pointer? Or do the remaining plain C-language accesses somehow avoid > running concurrently with those new WRITE_ONCE() invocations? > It can be concurrent. I was thinking about it. For some reason i decided to keep readers as a "regular" ones for loading the krcp->head. In this case it might take time for readers to see an updated value as a worst case scenario. So i need to update it or upload one more patch on top of v2. Should i upload a new patch? Thanks! -- Uladzislau Rezki
