Messages in this thread | | | Date | Fri, 17 Jan 2020 13:32:53 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] net: optimize cmpxchg in ip_idents_reserve |
| |
On Fri, Jan 17, 2020 at 02:54:03PM +0800, Shaokun Zhang wrote: > So how about this? ;-) > > delta = prandom_u32_max(now - old); > > +#ifdef CONFIG_UBSAN > /* Do not use atomic_add_return() as it makes UBSAN unhappy */ > + old = (u32)atomic_read(p_id); > do { > - old = (u32)atomic_read(p_id); > new = old + delta + segs; > - } while (atomic_cmpxchg(p_id, old, new) != old); > + } while (!atomic_try_cmpxchg(p_id, &old, new)); > +#else > + new = atomic_add_return(segs + delta, p_id); > +#endif
That's crazy, just accept that UBSAN is taking bonghits and ignore it. Use atomic_add_return() unconditionally.
| |