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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 EDFCDC169C4 for ; Mon, 11 Feb 2019 14:31:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC59420838 for ; Mon, 11 Feb 2019 14:31:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549895468; bh=gIzvRU08LGY965BkuXGR12BJO9FINRvrm4nnS73jhus=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=O+w2ONnzUBYl8Wuh3K0V9juDtSOCuXKPML0s/Q/eQScraDQmxh5wEQgleTfYnI1Cu CO5tV92tB4PA9SB5PYXfV33EcxAHsXy9LwCvVSEmrBT0snib6n2cabv+f7MKX8+feM CED7qxYg2etIyZL0uMdpXPj5QUoiViuKWrsPoKmE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730239AbfBKObH (ORCPT ); Mon, 11 Feb 2019 09:31:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:37732 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729593AbfBKObE (ORCPT ); Mon, 11 Feb 2019 09:31:04 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 61CB420675; Mon, 11 Feb 2019 14:31:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549895463; bh=gIzvRU08LGY965BkuXGR12BJO9FINRvrm4nnS73jhus=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ryi2x+YM/ybUYlruUW9xpmNoaU8hhx9auDI8XbGRIfi7e8s/VUn++zXKpuceZ1fSx wfBnDNtSXqm4Ea6kxltxq10y4dCnr8vMENQGPNC8cQnS1oPwRD3jUE/hl+cOVJkG81 JAX9lP9sc0SABfuTNdMjdVWaDEQRki5S1JLmJ6rM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Geert Uytterhoeven , Simon Horman , Sasha Levin Subject: [PATCH 4.20 182/352] serial: sh-sci: Fix locking in sci_submit_rx() Date: Mon, 11 Feb 2019 15:16:49 +0100 Message-Id: <20190211141858.671251270@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190211141846.543045703@linuxfoundation.org> References: <20190211141846.543045703@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.20-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit dd1f2250da95e87cb3e612858f94b14f99445a7c ] 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 Reviewed-by: Simon Horman Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- 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 cc56cb3b3eca..613007d7165e 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 */ -- 2.19.1