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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DB08C74A5B for ; Wed, 29 Mar 2023 07:51:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 795BD6B0075; Wed, 29 Mar 2023 03:51:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 745A66B0078; Wed, 29 Mar 2023 03:51:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63508900002; Wed, 29 Mar 2023 03:51:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 54B116B0075 for ; Wed, 29 Mar 2023 03:51:59 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 2959980BF8 for ; Wed, 29 Mar 2023 07:51:59 +0000 (UTC) X-FDA: 80621167158.23.B027A60 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf22.hostedemail.com (Postfix) with ESMTP id E2DCFC0019 for ; Wed, 29 Mar 2023 07:51:55 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=DjYX9Yfv; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=none (imf22.hostedemail.com: domain of mcgrof@infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=mcgrof@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1680076316; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+xoloHvgkvnUwe+7/mW4SGlzimEaFuLJW1cg0sgwA58=; b=RtfjEVyzH2yTChcANs3/6bxIHcqIfyQIQgL8zOBJ5zwpdwR0CYGC16xgoy1fLFMvKZcd8g bogyVKY0dwTCDJqSyFE8/Gv0WuRhGAR7BolWDM7Xl/DZx42Vmr/4rqi0DwjcfsmyKJb8Mp PboHTS7psZ9RS4E9tHFcQ2A14vu+xw4= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=DjYX9Yfv; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=none (imf22.hostedemail.com: domain of mcgrof@infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=mcgrof@infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1680076316; a=rsa-sha256; cv=none; b=qD2t9cX5PL3u1S/wP5+igHrW2fN2suutMpxIQorudcbIlQPykFEjz2Vv3s5JpXw2+J+YSQ ORA8Cekys1LSi+1+zh8rsgUluH1UxPbpKyKZDQaqiSi7Ea27m30PPNrFtjO3HYRNXxydfh 84xGEgq6/gJUyAESDuM8tnjfFHaUM9Y= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=+xoloHvgkvnUwe+7/mW4SGlzimEaFuLJW1cg0sgwA58=; b=DjYX9YfvtOFYsLi2tr8jvgeYc0 xWYqoPI1MrDacRMh6Pm4KaJs2gHpJ/wy4G02uqxMSMs/CM5G6r3RQaAf4WPjK9/caYmZpBr7RzcV+ MomD4y0ZyP43q6qy80wes0rvLXilUmDaVZhqwQRqySsyN8YD0PFcrWu1iG/iOuROX9VXWJ2zPMRyC rsceboL9zWFzjT9+nUOhskUitKzIPA3SlreHvnwsocTUmWMTexgmVVzKRwl0kEB+2VYz5PJbaJSxJ cL/lMy5nWX+e14Xv2PvoNDBb9j4Ikclt485t/MeuwMZsSi79eRpIb+IU27fSPe/Pr4eRzeyB8/FGH xIQrC0sA==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1phQay-00Gy5R-32; Wed, 29 Mar 2023 07:51:48 +0000 Date: Wed, 29 Mar 2023 00:51:48 -0700 From: Luis Chamberlain To: Peter Zijlstra Cc: david@redhat.com, patches@lists.linux.dev, linux-modules@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, pmladek@suse.com, petr.pavlu@suse.com, prarit@redhat.com, torvalds@linux-foundation.org, gregkh@linuxfoundation.org, rafael@kernel.org, christophe.leroy@csgroup.eu, tglx@linutronix.de, song@kernel.org, rppt@kernel.org, willy@infradead.org, vbabka@suse.cz, mhocko@suse.com, dave.hansen@linux.intel.com Subject: Re: [PATCH 4/7] sempahore: add a helper for a concurrency limiter Message-ID: References: <20230329053149.3976378-1-mcgrof@kernel.org> <20230329053149.3976378-5-mcgrof@kernel.org> <20230329072112.GG4253@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230329072112.GG4253@hirez.programming.kicks-ass.net> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E2DCFC0019 X-Stat-Signature: phnbgesm7wbdat5ishhjz8s3na6dxka3 X-HE-Tag: 1680076315-517263 X-HE-Meta: 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 wYDue6/2 pnUkrsCLTM2kpiqbTSWESx53fOchKrYvxB6tXP6uf5FWuV0aNh3oPN7n4ZFd/EnH5oEs0mqDke8udEfeeCS6TABuBEg2ZgXY0H92fDmQvui60+XQWbDR+HrNOG3wjeN1oWp0IK3HrMRxt7fvj18QDFHmt2BIPBzPde1uLkQcrDgnwHN3k2Y0d/mk2aYpicANQwOR1CJI4+jnbz/CFVmI4fZ8YjZSfGGyixjFuTiHhdghWzCt+dx22MmiiLZgcdNttli1N5dnbaMgwuoZGhj0sirupZuMK/obpKPYDBQaTWdi81Ua4Wu8qMjQbA2lY8EwkPuBnrhtF85D/tnO30GE+G8gGPhzy6DRHz2b2ecmWcJk8Rd7ZMMhYugJ7TA/sSyFRLT5UW+zRYFbEfsn2Vrsa0tuqZZD4xeTGFaQk5u5nbDg2WzSGASkAOseI57YXocAcwRBeKcgLVN+xU2+Gn/xJ8SJ+ig== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 29, 2023 at 09:21:12AM +0200, Peter Zijlstra wrote: > On Tue, Mar 28, 2023 at 10:31:46PM -0700, Luis Chamberlain wrote: > > While I looked at re-using the old kernel/kmod.c (now kernel/module/kmod.c) > > concurrency delimiter methodology for another place in the kernel Linus > > noted that this could be simply replaced with a sempahore [0]. > > > > So add that so we we don't re-invent the wheel and make it obvious to use. > > > > [0] https://lore.kernel.org/all/CAHk-=whkj6=wyi201JXkw9iT_eTUTsSx+Yb9d4OgmZFjDJA18g@mail.gmail.com/ > > > > Suggested-by: Linus Torvalds > > Signed-off-by: Luis Chamberlain > > --- > > include/linux/semaphore.h | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h > > index 6694d0019a68..2ecdffdb9814 100644 > > --- a/include/linux/semaphore.h > > +++ b/include/linux/semaphore.h > > @@ -28,6 +28,9 @@ struct semaphore { > > #define DEFINE_SEMAPHORE(name) \ > > struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1) > > > > +#define CONCURRENCY_LIMITER(name, n) \ > > + struct semaphore name = __SEMAPHORE_INITIALIZER(name, n) > > + > > Why should this live in semaphore.h? I have no preference, but sharing seems to have been better. Do you have any recommendations? Luis