From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00350C433F5 for ; Tue, 10 May 2022 16:51:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347682AbiEJQy4 (ORCPT ); Tue, 10 May 2022 12:54:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347693AbiEJQyu (ORCPT ); Tue, 10 May 2022 12:54:50 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B76F21240 for ; Tue, 10 May 2022 09:50:52 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id qe3-20020a17090b4f8300b001dc24e4da73so2032711pjb.1 for ; Tue, 10 May 2022 09:50:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=+OrGejelLd0/r3wyZ5B1hnRpKSyjyIABgvgW47LLooY=; b=Gt3pUi+fMXEx3yt2N7YDLecB+fh8bnsLUAhNGUelGqYArf8brh67ItBKmaEnAgRcJZ Xn0T4bUlGe+xa2Q61dbd1UN2FxULHx3pyMndliDEIMP27wn1EQOW7+KCOIZCsvJeBMyq 2XF7RfKJS4EUpzD9NKR3C7JBY30zzrejdnYVVu5ztvIJBW4OvjIlkwg5vVRtViCmSuaW E3KMSYj3+0wXUIm7Mi6iNv083gU+nI64HjxkquUcTG3XfwIqFihSO/nHoKEXIMo8wOKt Z7Ufq5YVcpRQc7kOVM/cW5bAA2pX+FHJK9wkUK3GsyEHYrWOVxot2YGDtoXUT8P4+QC4 PiKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=+OrGejelLd0/r3wyZ5B1hnRpKSyjyIABgvgW47LLooY=; b=69m9ew3UAcnk2c8nDRQfoJa1xWSmXrrPyF7U6hcZsVihMFwPpH1J/Gan7Nnvy93KZO h9KkieDbTLIOaJXcIOl6j8J+W/Qtcg76CYUqEobzWx/q01usSov4cmgpBTZgTsR1vkDM X9eGgT8isMfLX/pTkorFodER/6JDRtqrFAg8RifnoWNLVvA110EKbaSW9qUSyQytv8YA TNcABhIddoAwM0b0GAam9BZ87UNhaZQUWsyaPl8Ml698Zy5x4E4ug6PRaxoWhoRVTX/9 w5e1CGhXSJjIuJG9JQs42LRdLc1K1SJOp1y99D9kQuj3haITB0+m+kyyGohfj2z8ojfy 4vaQ== X-Gm-Message-State: AOAM533kQRAeMckLuUmjGEEgnH0G3z0GedLYcM6Dpv5mKL0U9zdNbVfr QU02M5nQDQMe0fc+q8df0L4GxS6icUsQQh/r60c= X-Google-Smtp-Source: ABdhPJwffULAkMAIgasr7aNCVYP16kgnCweiJCKt6lygDrJlUDTcxhAsvV/eEsmYgsYZy1m3uAjEKYK6SpK8RmgIbKQ= X-Received: by 2002:a17:90a:8591:b0:1b9:da10:2127 with SMTP id m17-20020a17090a859100b001b9da102127mr818585pjn.13.1652201451374; Tue, 10 May 2022 09:50:51 -0700 (PDT) MIME-Version: 1.0 References: <20220510154750.212913-1-yury.norov@gmail.com> <20220510154750.212913-9-yury.norov@gmail.com> In-Reply-To: <20220510154750.212913-9-yury.norov@gmail.com> From: Alexei Starovoitov Date: Tue, 10 May 2022 09:50:40 -0700 Message-ID: Subject: Re: [PATCH 08/22] bitops: introduce MANY_BITS() macro To: Yury Norov Cc: Andy Shevchenko , David Laight , Greg Kroah-Hartman , Joe Perches , Julia Lawall , =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Nicholas Piggin , Nicolas Palix , Peter Zijlstra , Rasmus Villemoes , Matti Vaittinen , LKML , Alexei Starovoitov , Andrew Morton , Chris Zankel , Christophe Leroy , "Eric W . Biederman" , Kumar Kartikeya Dwivedi , Max Filippov , =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= , linux-xtensa@linux-xtensa.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 10, 2022 at 8:48 AM Yury Norov wrote: > > arch/xtensa/kernel/traps.c and include/linux/log2.h define very similar > functions with different behaviour. XTENSA defines IS_POW2(), and > log2.h defines is_power_of_2(). The difference is that IS_POW2() > considers 0 as power of 2, while is_power_of_2() - does not. > > This discrepancy may confuse reader. From mathematical point of view, > 0 is not a power of 2. So let's introduce macro MANY_BITS(), which > returns true if 2 or more bits are set in a number (which is what > XTENSA actually needs), and use it in is_power_of_2(). > > CC: Alexei Starovoitov > CC: Andrew Morton > CC: Chris Zankel > CC: Christophe Leroy > CC: Eric W. Biederman > CC: Kumar Kartikeya Dwivedi > CC: Max Filippov > CC: Toke H=C3=B8iland-J=C3=B8rgensen > CC: linux-xtensa@linux-xtensa.org > CC: linux-kernel@vger.kernel.org > Signed-off-by: Yury Norov > --- > arch/xtensa/kernel/traps.c | 5 +---- > include/linux/bitops.h | 3 +++ > include/linux/log2.h | 2 +- > 3 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c > index 138a86fbe9d7..040ec38bfce2 100644 > --- a/arch/xtensa/kernel/traps.c > +++ b/arch/xtensa/kernel/traps.c > @@ -203,10 +203,7 @@ static void do_multihit(struct pt_regs *regs) > > #if XTENSA_FAKE_NMI > > -#define IS_POW2(v) (((v) & ((v) - 1)) =3D=3D 0) > - > -#if !(PROFILING_INTLEVEL =3D=3D XCHAL_EXCM_LEVEL && \ > - IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL))) > +#if (MANY_BITS(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)) || PROFILING_IN= TLEVEL !=3D XCHAL_EXCM_LEVEL) > #warning "Fake NMI is requested for PMM, but there are other IRQs at or = above its level." > #warning "Fake NMI will be used, but there will be a bugcheck if one of = those IRQs fire." > > diff --git a/include/linux/bitops.h b/include/linux/bitops.h > index 7aaed501f768..96bc6a2552d6 100644 > --- a/include/linux/bitops.h > +++ b/include/linux/bitops.h > @@ -21,6 +21,9 @@ > #define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PE= R_TYPE(u32)) > #define BITS_TO_BYTES(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(c= har)) > > +/* Return: nonzero if 2 or more bits are set */ > +#define MANY_BITS(n) ((n) & ((n) - 1)) > + > extern unsigned int __sw_hweight8(unsigned int w); > extern unsigned int __sw_hweight16(unsigned int w); > extern unsigned int __sw_hweight32(unsigned int w); > diff --git a/include/linux/log2.h b/include/linux/log2.h > index 9f30d087a128..335b9dbd302d 100644 > --- a/include/linux/log2.h > +++ b/include/linux/log2.h > @@ -44,7 +44,7 @@ int __ilog2_u64(u64 n) > static inline __attribute__((const)) > bool is_power_of_2(unsigned long n) > { > - return (n !=3D 0 && ((n & (n - 1)) =3D=3D 0)); > + return n !=3D 0 && !MANY_BITS(n); > } Please don't. Open coded version is much easier to read.