| Message ID | 1621930520-515336-2-git-send-email-wubo40@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | use DIV_ROUND_UP helper macro for calculations | expand |
Wu Bo <wubo40@huawei.com> a écrit : > From: Wu Bo <wubo40@huawei.com> > > Replace open coded divisor calculations with the DIV_ROUND_UP kernel > macro for better readability. > > Signed-off-by: Wu Bo <wubo40@huawei.com> > --- > 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() > if (WARN_ON(npages == 0)) > return -EINVAL; > /* Add one extra for linking */ > -- > 1.8.3.1
On Tue, May 25, 2021 at 10:37:44AM +0200, Christophe Leroy wrote: > Wu Bo <wubo40@huawei.com> a écrit : > > > From: Wu Bo <wubo40@huawei.com> > > > > Replace open coded divisor calculations with the DIV_ROUND_UP kernel > > macro for better readability. > > > > Signed-off-by: Wu Bo <wubo40@huawei.com> > > --- > > 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.
On Tue, May 25, 2021 at 04:15:19PM +0800, Wu Bo wrote: > From: Wu Bo <wubo40@huawei.com> > > Replace open coded divisor calculations with the DIV_ROUND_UP kernel > macro for better readability. > > Signed-off-by: Wu Bo <wubo40@huawei.com> > --- > crypto/af_alg.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Patch applied. Thanks.
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); if (WARN_ON(npages == 0)) return -EINVAL; /* Add one extra for linking */