* Jason A. Donenfeld: > +retry_generation: > + /* > + * @rng_info->generation must always be read here, as it serializes @state->key with the > + * kernel's RNG reseeding schedule. > + */ > + current_generation = READ_ONCE(rng_info->generation); > + if (unlikely(READ_ONCE(state->generation) != READ_ONCE(rng_info- I'm pretty sure you need some sort of barrier here. We have a similar TM-lite construct in glibc ld.so for locating link maps by address, and there the compiler performed reordering. _dl_find_object miscompilation on powerpc64le <https://sourceware.org/bugzilla/show_bug.cgi?id=28745> I'm not familiar with READ_ONCE, but Documentation/atomic_t.txt suggests it's a “regular LOAD”, and include/asm-generic/rwonce.h concurs. Likewise, the signal safety mechanism needs compiler barriers (signal fences). I'm also not sure how READ_ONCE realizes atomic 64-bit reads on 32-bit platforms. i386 can do them in user space via the FPU worst-case (if the control word hasn't been corrupted). CMPXCHG8B is not applicable here because it's a read-only mapping. Maybe add a comment at least about that “strong prevailing wind”? Thanks, Florian
