* Linus Torvalds (torvalds@xxxxxxxxxxxxxxxxxxxx) wrote: > > > On Fri, 25 Apr 2008, Ingo Molnar wrote: > > > > something like the patch below? (untested) > > No. That whole code sequence is total and utter crap. It needs to be > rewritten. > > It first does a BUG_ON() if it's not naturally aligned (because that > wouldn't be atomic), and then it has code for page crossing! What a TOTAL > PIECE OF SH*T! > > Hint: > - if it's naturally aligned, it couldn't be page crossing ANYWAY > - and if it was a page-crosser, it sure as hell couldn't be atomic! > > The code is just crap, crap, crap. It needs to be rewritten from scratch. > I'll have a patch soonish. > > Linus Woooow, just a sec here. I removed the atomicity test _because_ there happen to be a case where it's safe to do non-atomic instruction modification. If we do : 1) replace the instruction first byte by a breakpoint, execute an instruction bypass (see the immediate values patches for detail) 2) modify the instruction non-atomically 3) put back the original instruction first byte. That's why I removed the BUG_ONs at the beginning of the function. That's also why it's required to deal with page crossing. Mathieu -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
