On Tue, May 25, 2021 at 10:37:44AM +0200, Christophe Leroy wrote: > Wu Bo <wubo40@xxxxxxxxxx> a écrit : > > > From: Wu Bo <wubo40@xxxxxxxxxx> > > > > Replace open coded divisor calculations with the DIV_ROUND_UP kernel > > macro for better readability. > > > > Signed-off-by: Wu Bo <wubo40@xxxxxxxxxx> > > --- > > crypto/af_alg.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/crypto/af_alg.c b/crypto/af_alg.c > > index 18cc82d..8bd288d 100644 > > --- a/crypto/af_alg.c > > +++ b/crypto/af_alg.c > > @@ -411,7 +411,7 @@ int af_alg_make_sg(struct af_alg_sgl *sgl, struct > > iov_iter *iter, int len) > > if (n < 0) > > return n; > > > > - npages = (off + n + PAGE_SIZE - 1) >> PAGE_SHIFT; > > + npages = DIV_ROUND_UP(off + n, PAGE_SIZE); > > You should use PFN_UP() No. We are not using pfns here - we're converting a byte count to a page count. Besides, "PFN_UP" is a horrible, awful api. It does not decribe what it does and anyone who is not a mm developer will look at it and ask "what <the ....> does this do?" and have to go looking for it's definition to determine what it does. Yes, that's exactyl what I've just done, and I really wish I didn't because, well, it just reinforces how much we suck at APIs... OTOH, what DIV_ROUND_UP() does is obvious, widely understood, self documenting and easy to determine if the usage is correct, which indeed this is. The lesson: do not use whacky obscure, out of context macros when a simple, obvious, widely known macro will give the same result and make the code easier to understand. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
