On Thu, May 28, 2015 at 9:59 AM, Cyrill Gorcunov <gorcu...@gmail.com> wrote: > On Thu, May 28, 2015 at 02:12:07AM +0300, Alexey Dobriyan wrote: >> > > > >> > > > Could you please explain why this down/up is needed? >> > > >> > > Code is written this way to get constistent snapshot of data. >> > >> > it does not. you fetch data into local variables which is the >> > same as simply read them locklessly in general (because later >> > you refer to local vars). >> >> It is snapshot w.r.t getting both pairs not snapshot w.r.t atomicity or >> something (unsigned long access is atomic after all). Once down_write() >> is used in the other place, it even becomes obviously correct code! > > Not at all. It is correct if and only if you're operating under lock > taken, once you fetch the pair and left the lock it simply local copies > of values the descriptor had when lock was taken.
Yes, and? You do not complain that signal statistics is collected under sighand lock but printed for /proc/*/status without, do you? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
