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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F180EC282CE for ; Tue, 4 Jun 2019 11:47:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6D95245BC for ; Tue, 4 Jun 2019 11:47:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jRytlmPG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727616AbfFDLrG (ORCPT ); Tue, 4 Jun 2019 07:47:06 -0400 Received: from merlin.infradead.org ([205.233.59.134]:36108 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727433AbfFDLrG (ORCPT ); Tue, 4 Jun 2019 07:47:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9wuTa603w+SqStPamvP3MUdukRk8xI2CxDP7Kut8vY0=; b=jRytlmPG1KD1jUNei/lIj+aVy 0iVLl7FLtEYXL4AFb8/rF1RnkD5pn0ucGDVaH1a2rvvEzfiS8UkBLX4wDMEet88gjZ2xOp7YX8z87 iJjkRgx4Y3hnHpZMW7OFgDSX+ckdsN/0YVE+HvPXWoJE6ekz1m+1dmNqnyGwrEdCAb4QB8+EdLreW bL/kO0RkQuj+vdtyqDo2LlhhP26U4qxRV4TsKd1tILh/hAG6f/jOuZJnyBqRoCW0TmfPSE4W5csJB OTF1dkNtU8SjWKv/hC4NBYvj4NeMZpDg0dRW/3JXxpLDTF/9CwOm9ZpyF3LHYr/5+SyIoz7E84ztX 269eLr9gQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hY7uB-0004ZW-24; Tue, 04 Jun 2019 11:47:03 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 754BD20114D6C; Tue, 4 Jun 2019 13:47:01 +0200 (CEST) Date: Tue, 4 Jun 2019 13:47:01 +0200 From: Peter Zijlstra To: Christoph Hellwig Cc: x86@kernel.org, Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] x86/fpu: Simplify kernel_fpu_begin Message-ID: <20190604114701.GM3402@hirez.programming.kicks-ass.net> References: <20190604071524.12835-1-hch@lst.de> <20190604071524.12835-3-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190604071524.12835-3-hch@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 04, 2019 at 09:15:23AM +0200, Christoph Hellwig wrote: > +void kernel_fpu_begin(void) > { > + preempt_disable(); > > WARN_ON_FPU(!irq_fpu_usable()); > + WARN_ON_FPU(this_cpu_read(in_kernel_fpu)); > > + this_cpu_write(in_kernel_fpu, true); > > + if (current->mm && !test_thread_flag(TIF_NEED_FPU_LOAD)) { Did that want to be: !(current->flags & PF_KTHREAD), instead? Because I'm thinking that kernel_fpu_begin() on a kthread that has use_mm() employed shouldn't be doing this.. > + set_thread_flag(TIF_NEED_FPU_LOAD); > + /* > + * Ignore return value -- we don't care if reg state > + * is clobbered. > + */ > + copy_fpregs_to_fpstate(¤t->thread.fpu); > } > __cpu_invalidate_fpregs_state(); > }