From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C5F37223DD6; Wed, 18 Feb 2026 22:26:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771453613; cv=none; b=HVrHNt4IUEen9Cw3KUScSefK4CjB7+IaZmtoHKezrPo5o1WgEJ1cbeKbKElHmyyGzMcGi5F+x2QKDxEIOxyo0HF6t0keGxdee4FHEkDqgXCNCCcrrFzrb9RUETXrJiU3xPz64K+DNAEou57Ih4aCQWG6T68SufQxIkoU+9LhQDI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771453613; c=relaxed/simple; bh=iaIACN78TBqP85RyQV7yWMmTo81+wzL0JQ8VxTQglw8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DkDcMmcl2w37LVCJIUTBoTrz4MxWuwAAQq6ogRSzJHWcnOzCq/zUDRTaaEdh8j+u+TgdWNOtdk/aLScB94vpItFjHvjHruX+y3BT0/zoqi/sKMCWLU5qCQfO8kk1gsIIs0lHNdVhb1XJOBFMc1ze2iytZ+ztIUNl8XB7Cdj4wX8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=YCaFgtec; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YCaFgtec" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=V+AI2PSMhjEy+wYOIImmve2/jF2yiEoqib372fgT190=; b=YCaFgtecU9AVUeUGy1lSw7VSZW sVS4j6D4XfaarXSs8Qr+KCMOxlWc/Np7dR8/ALOxZJFNBcaobuYgmIDqqNQGdQ1Z1ZclhxRktlNeb 8Rl+imJFIpY7e0writro7uZUvW1HG0rlF97noD8zU8nUaB29NZOfMtG2LCYye+Kr8OZlffkumMBB3 msH2xWxqouToALfbCU1tYk0cDGOCbHfBVOLhoGC83Xvx/+qExF386nLF5SVUA4Tkw1i7a6pWBz499 kg4MWO7eWKfOh/6BTyNi16AwDOVqq6SYDt/2Hsa4Dq/j4YhtDEexl0pqM0xRb+fF542eyibVI/5So 6rEASZGw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vsq0K-00000006jhG-3PA8; Wed, 18 Feb 2026 22:26:45 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 9814A300B40; Wed, 18 Feb 2026 23:26:43 +0100 (CET) Date: Wed, 18 Feb 2026 23:26:43 +0100 From: Peter Zijlstra To: Matthew Wilcox Cc: Linus Torvalds , Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , linux-kernel@vger.kernel.org, Christoph Hellwig , linux-fsdevel@vger.kernel.org Subject: Re: [RFC 1/1] rwsem: Shrink rwsem by one pointer Message-ID: <20260218222643.GC1395266@noisy.programming.kicks-ass.net> References: <20260217190835.1151964-1-willy@infradead.org> <20260217190835.1151964-2-willy@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Feb 18, 2026 at 09:00:14PM +0000, Matthew Wilcox wrote: > Here's all the changes I made, and I'll post a rolled-up version > next. That all seems reasonable. One small nit: > + if (list_empty(&waiter->list)) { > + sem->first_waiter = NULL; > + return true; > } > > + if (sem->first_waiter == waiter) > + sem->first_waiter = list_first_entry(&waiter->list, > + struct rwsem_waiter, list); Since that's multiple lines, could you wrap in {}, also I tend to prefer cino=(0:0 style wrapping. That is, something like so: if (sem->first_waiter == waiter) { sem->first_waiter = list_first_entry(&waiter->list, struct rwsem_waiter, list); } > + list_del(&waiter->list); > + > return false; > }