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Date: Tue, 25 Jan 2022 13:09:58 -0800 From: Yury Norov <yury.norov@...il.com> To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> Cc: Rasmus Villemoes <linux@...musvillemoes.dk>, Andrew Morton <akpm@...ux-foundation.org>, Michał Mirosław <mirq-linux@...e.qmqm.pl>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Peter Zijlstra <peterz@...radead.org>, David Laight <David.Laight@...lab.com>, Joe Perches <joe@...ches.com>, Dennis Zhou <dennis@...nel.org>, Emil Renner Berthing <kernel@...il.dk>, Nicholas Piggin <npiggin@...il.com>, Matti Vaittinen <matti.vaittinen@...rohmeurope.com>, Alexey Klimov <aklimov@...hat.com>, linux-kernel@...r.kernel.org, Ariel Elior <aelior@...vell.com>, Manish Chopra <manishc@...vell.com>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org Subject: Re: [PATCH 10/54] net: ethernet: replace bitmap_weight with bitmap_empty for qlogic On Mon, Jan 24, 2022 at 4:29 AM Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote: > > On Sun, Jan 23, 2022 at 10:38:41AM -0800, Yury Norov wrote: > > qlogic/qed code calls bitmap_weight() to check if any bit of a given > > bitmap is set. It's better to use bitmap_empty() in that case because > > bitmap_empty() stops traversing the bitmap as soon as it finds first > > set bit, while bitmap_weight() counts all bits unconditionally. > > > - if (bitmap_weight((unsigned long *)&pmap[item], 64 * 8)) > > + if (!bitmap_empty((unsigned long *)&pmap[item], 64 * 8)) > > > - (bitmap_weight((unsigned long *)&pmap[item], > > + (!bitmap_empty((unsigned long *)&pmap[item], > > Side note, these castings reminds me previous discussion and I'm wondering > if you have this kind of potentially problematic places in your TODO as > subject to fix. In the discussion you mentioned above, the u32* was cast to u64*, which is wrong. The code here is safe because in the worst case, it casts u64* to u32*. This would be OK wrt -Werror=array-bounds. The function itself looks like doing this unsigned long <-> u64 conversions just for printing purpose. I'm not a qlogic expert, so let's wait what people say? The printing part may be refactored although to use %pb" format, similarly to the snippet below (not tested). Thanks, Yury diff --git a/drivers/net/ethernet/qlogic/qed/qed_rdma.c b/drivers/net/ethernet/qlogic/qed/qed_rdma.c index 23b668de4640..72505517ced1 100644 --- a/drivers/net/ethernet/qlogic/qed/qed_rdma.c +++ b/drivers/net/ethernet/qlogic/qed/qed_rdma.c @@ -336,17 +336,8 @@ void qed_rdma_bmap_free(struct qed_hwfn *p_hwfn, /* print aligned non-zero lines, if any */ for (item = 0, line = 0; line < last_line; line++, item += 8) - if (bitmap_weight((unsigned long *)&pmap[item], 64 * 8)) - DP_NOTICE(p_hwfn, - "line 0x%04x: 0x%016llx 0x%016llx 0x%016llx 0x%016llx 0x%016llx 0x%016llx 0x%016llx 0x%016llx\n", - line, - pmap[item], - pmap[item + 1], - pmap[item + 2], - pmap[item + 3], - pmap[item + 4], - pmap[item + 5], - pmap[item + 6], pmap[item + 7]); + if (bitmap_weight(bmap->bitmap, 64 * 8)) + DP_NOTICE(p_hwfn, "line 0x%04x: %512pb\n", line, bmap->bitmap); /* print last unaligned non-zero line, if any */ if ((bmap->max_count % (64 * 8)) &&
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