On Tue, Mar 28, 2017 at 11:51 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > >> On Tue, Mar 28, 2017 at 09:52:32AM +0200, Ingo Molnar wrote: >> >> > No, regular C code. >> > >> > I don't see the point of generating all this code via CPP - it's certainly not >> > making it more readable to me. I.e. this patch I commented on is a step backwards >> > for readability. >> >> Note that much of the atomic stuff we have today is all CPP already. > > Yeah, but there it's implementational: we pick up arch primitives depending on > whether they are defined, such as: > > #ifndef atomic_read_acquire > # define atomic_read_acquire(v) smp_load_acquire(&(v)->counter) > #endif > >> x86 is the exception because its 'weird', but most other archs are >> almost pure CPP -- check Alpha for example, or asm-generic/atomic.h. > > include/asm-generic/atomic.h looks pretty clean and readable overall. > >> Also, look at linux/atomic.h, its a giant maze of CPP. > > Nah, that's OK, much of is is essentially __weak inlines implemented via CPP - > i.e. CPP is filling in a missing compiler feature. > > But this patch I replied to appears to add instrumentation wrappery via CPP which > looks like excessive and avoidable obfuscation to me. > > If it's much more readable and much more compact than the C version then maybe, > but I'd like to see the C version first and see ... > >> The CPP help us generate functions, reduces endless copy/paste (which induces >> random differences -- read bugs) and construct variants depending on the >> architecture input. >> >> Yes, the CPP is a pain, but writing all that out explicitly is more of a >> pain. > > So I'm not convinced that it's true in this case. > > Could we see the C version and compare? I could be wrong about it all. Here it is (without instrumentation): https://gist.github.com/dvyukov/e33d580f701019e0cd99429054ff1f9a Instrumentation will add for each function: static __always_inline void atomic64_set(atomic64_t *v, long long i) { + kasan_check_write(v, sizeof(*v)); arch_atomic64_set(v, i); } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
