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=-8.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 56FA2C67872 for ; Thu, 13 Dec 2018 18:44:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2FE0820851 for ; Thu, 13 Dec 2018 18:44:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2FE0820851 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=glider.be Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-renesas-soc-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726662AbeLMSos (ORCPT ); Thu, 13 Dec 2018 13:44:48 -0500 Received: from andre.telenet-ops.be ([195.130.132.53]:49214 "EHLO andre.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726381AbeLMSor (ORCPT ); Thu, 13 Dec 2018 13:44:47 -0500 Received: from ramsan ([84.194.111.163]) by andre.telenet-ops.be with bizsmtp id BWkl1z00K3XaVaC01Wklyl; Thu, 13 Dec 2018 19:44:46 +0100 Received: from rox.of.borg ([192.168.97.57]) by ramsan with esmtp (Exim 4.90_1) (envelope-from ) id 1gXVyX-0007qp-Dt; Thu, 13 Dec 2018 19:44:45 +0100 Received: from geert by rox.of.borg with local (Exim 4.90_1) (envelope-from ) id 1gXVyX-0005i7-CR; Thu, 13 Dec 2018 19:44:45 +0100 From: Geert Uytterhoeven To: Greg Kroah-Hartman , Jiri Slaby Cc: Ulrich Hecht , Wolfram Sang , Yoshihiro Shimoda , Yoshinori Sato , linux-renesas-soc@vger.kernel.org, linux-sh@vger.kernel.org, linux-serial@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH v4 1/4] serial: sh-sci: Fix locking in sci_submit_rx() Date: Thu, 13 Dec 2018 19:44:41 +0100 Message-Id: <20181213184444.21904-2-geert+renesas@glider.be> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181213184444.21904-1-geert+renesas@glider.be> References: <20181213184444.21904-1-geert+renesas@glider.be> Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org Some callers of sci_submit_rx() hold the port spinlock, others don't. During fallback to PIO, the driver needs to obtain the port spinlock. If the lock was already held, spinlock recursion is detected, causing a deadlock: BUG: spinlock recursion on CPU#0. Fix this by adding a flag parameter to sci_submit_rx() for the caller to indicate the port spinlock is already held, so spinlock recursion can be avoided. Move the spin_lock_irqsave() up, so all DMA disable steps are protected, which is safe as the recently introduced dmaengine_terminate_async() can be called in atomic context. Signed-off-by: Geert Uytterhoeven --- v4: - No changes, v3: - Split in multiple patches. --- drivers/tty/serial/sh-sci.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 8146d9cef0cbe2d0..2a08039f792235e5 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1331,7 +1331,7 @@ static void sci_tx_dma_release(struct sci_port *s) dma_release_channel(chan); } -static void sci_submit_rx(struct sci_port *s) +static void sci_submit_rx(struct sci_port *s, bool port_lock_held) { struct dma_chan *chan = s->chan_rx; struct uart_port *port = &s->port; @@ -1362,16 +1362,18 @@ static void sci_submit_rx(struct sci_port *s) return; fail: + /* Switch to PIO */ + if (!port_lock_held) + spin_lock_irqsave(&port->lock, flags); if (i) dmaengine_terminate_async(chan); for (i = 0; i < 2; i++) s->cookie_rx[i] = -EINVAL; s->active_rx = -EINVAL; - /* Switch to PIO */ - spin_lock_irqsave(&port->lock, flags); s->chan_rx = NULL; sci_start_rx(port); - spin_unlock_irqrestore(&port->lock, flags); + if (!port_lock_held) + spin_unlock_irqrestore(&port->lock, flags); } static void work_fn_tx(struct work_struct *work) @@ -1491,7 +1493,7 @@ static enum hrtimer_restart rx_timer_fn(struct hrtimer *t) } if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) - sci_submit_rx(s); + sci_submit_rx(s, true); /* Direct new serial port interrupts back to CPU */ scr = serial_port_in(port, SCSCR); @@ -1617,7 +1619,7 @@ static void sci_request_dma(struct uart_port *port) s->chan_rx_saved = s->chan_rx = chan; if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) - sci_submit_rx(s); + sci_submit_rx(s, false); } } @@ -1667,7 +1669,7 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr) scr |= SCSCR_RDRQE; } else { scr &= ~SCSCR_RIE; - sci_submit_rx(s); + sci_submit_rx(s, false); } serial_port_out(port, SCSCR, scr); /* Clear current interrupt */ -- 2.17.1