From patchwork Mon Feb 24 14:07:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 11401043 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B582C14E3 for ; Mon, 24 Feb 2020 16:55:12 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9E31620836 for ; Mon, 24 Feb 2020 16:55:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E31620836 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B74E16E5CC; Mon, 24 Feb 2020 16:54:54 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by gabe.freedesktop.org (Postfix) with ESMTPS id 31EA56E50E for ; Mon, 24 Feb 2020 14:33:35 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=flow.W.breakpoint.cc) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1j6EOR-0003oV-Cb; Mon, 24 Feb 2020 15:07:31 +0100 From: Sebastian Andrzej Siewior To: VMware Graphics Subject: [PATCH 1/2] drm/vmwgfx: Drop preempt_disable() in vmw_fifo_ping_host() Date: Mon, 24 Feb 2020 15:07:25 +0100 Message-Id: <20200224140726.1550689-1-bigeasy@linutronix.de> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Mailman-Approved-At: Mon, 24 Feb 2020 16:54:53 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Hellstrom , Sebastian Andrzej Siewior , Thomas Gleixner , dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" vmw_fifo_ping_host() disables preemption around a test and a register write via vmw_write(). The write function acquires a spinlock_t typed lock which is not allowed in a preempt_disable()ed section on PREEMPT_RT. This has been reported in the bugzilla. It has been explained by Thomas Hellstrom that this preempt_disable()ed section is not required for correctness. Remove the preempt_disable() section. Link: https://bugzilla.kernel.org/show_bug.cgi?id=206591 Link: https://lkml.kernel.org/r/0b5e1c65d89951de993deab06d1d197b40fd67aa.camel@vmware.com Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Thomas Hellstrom --- drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c index e5252ef3812f0..6941689085ed3 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c @@ -169,10 +169,8 @@ void vmw_fifo_ping_host(struct vmw_private *dev_priv, uint32_t reason) { u32 *fifo_mem = dev_priv->mmio_virt; - preempt_disable(); if (cmpxchg(fifo_mem + SVGA_FIFO_BUSY, 0, 1) == 0) vmw_write(dev_priv, SVGA_REG_SYNC, reason); - preempt_enable(); } void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)