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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 BC676C433DF for ; Sat, 27 Jun 2020 19:47:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F6022067D for ; Sat, 27 Jun 2020 19:47:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VSmuDJeI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726693AbgF0TrP (ORCPT ); Sat, 27 Jun 2020 15:47:15 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:36379 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726057AbgF0TrN (ORCPT ); Sat, 27 Jun 2020 15:47:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593287232; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=06AlwKVkuVI6ElbE+J2x+1IfIbX5X762VJ0OLmfYmJ4=; b=VSmuDJeIuzVB2kawvDBAoIDSbMVy1LZRqs+7ZNXrAtKlUc4GTXusTBrilIXxq5oigX4pl+ 2XVLQEWG3OPrQ1B+rhY2Zur5AKiqgZcfQ3i58/f4l2tdWICJPp9Fv5lgSXnagJzazmz2aO gpAYLStPfkVCLkkmHsrZU/t7TUZKO1M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-228-arU-Ip_dOiihnId6YAtiWA-1; Sat, 27 Jun 2020 15:47:08 -0400 X-MC-Unique: arU-Ip_dOiihnId6YAtiWA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 90E90464; Sat, 27 Jun 2020 19:47:06 +0000 (UTC) Received: from Whitewolf.redhat.com (ovpn-112-223.rdu2.redhat.com [10.10.112.223]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7C65A7930D; Sat, 27 Jun 2020 19:47:05 +0000 (UTC) From: Lyude Paul To: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org Cc: Daniel Vetter , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , linux-kernel@vger.kernel.org (open list) Subject: [RFC v8 2/9] drm/vblank: Use spin_(un)lock_irq() in drm_crtc_vblank_off() Date: Sat, 27 Jun 2020 15:46:50 -0400 Message-Id: <20200627194657.156514-3-lyude@redhat.com> In-Reply-To: <20200627194657.156514-1-lyude@redhat.com> References: <20200627194657.156514-1-lyude@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This got me confused for a bit while looking over this code: I had been planning on adding some blocking function calls into this function, but seeing the irqsave/irqrestore variants of spin_(un)lock() didn't make it very clear whether or not that would actually be safe. So I went ahead and reviewed every single driver in the kernel that uses this function, and they all fall into three categories: * Driver probe code * ->atomic_disable() callbacks * Legacy modesetting callbacks All of these will be guaranteed to have IRQs enabled, which means it's perfectly safe to block here. Just to make things a little less confusing to others in the future, let's switch over to spin_lock_irq()/spin_unlock_irq() to make that fact a little more obvious. Signed-off-by: Lyude Paul Reviewed-by: Daniel Vetter Cc: Ville Syrjälä --- drivers/gpu/drm/drm_vblank.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index ce5c1e1d29963..e895f5331fdb4 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1283,13 +1283,12 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc) struct drm_pending_vblank_event *e, *t; ktime_t now; - unsigned long irqflags; u64 seq; if (drm_WARN_ON(dev, pipe >= dev->num_crtcs)) return; - spin_lock_irqsave(&dev->event_lock, irqflags); + spin_lock_irq(&dev->event_lock); spin_lock(&dev->vbl_lock); drm_dbg_vbl(dev, "crtc %d, vblank enabled %d, inmodeset %d\n", @@ -1325,7 +1324,7 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc) drm_vblank_put(dev, pipe); send_vblank_event(dev, e, seq, now); } - spin_unlock_irqrestore(&dev->event_lock, irqflags); + spin_unlock_irq(&dev->event_lock); /* Will be reset by the modeset helpers when re-enabling the crtc by * calling drm_calc_timestamping_constants(). */ -- 2.26.2