Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752745AbaLPAoR (ORCPT ); Mon, 15 Dec 2014 19:44:17 -0500 Received: from c-82-192-226-27.customer.ggaweb.ch ([82.192.226.27]:33667 "EHLO dizzy-6.o2s.ch" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752025AbaLPAoJ (ORCPT ); Mon, 15 Dec 2014 19:44:09 -0500 Subject: [PATCH 1/4] mmc: sunxi: Lock fix From: David =?utf-8?q?Lanzend=C3=B6rfer?= To: Ulf Hansson , Tomeu Vizoso , Arnd Bergmann , linux-mmc@vger.kernel.org, Chris Ball , linux-kernel@vger.kernel.org, Peter Griffin , Hans de Goede , Chen-Yu Tsai , David =?utf-8?q?Lanzend=C3=B6rfer?= , =?utf-8?b?5p2O5oOz?= , Maxime Ripard , linux-arm-kernel@lists.infradead.org Date: Tue, 16 Dec 2014 01:37:45 +0100 Message-ID: <20141216003745.15488.52305.stgit@dizzy-6.o2s.ch> In-Reply-To: <20141216003412.15488.54812.stgit@dizzy-6.o2s.ch> References: <20141216003412.15488.54812.stgit@dizzy-6.o2s.ch> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 1) Adding a comment in order to clarify the choice of the locks within sunxi_mmc_handle_manual_stop 2) As 李想 has pointed out the wait_dma variable was not accessed within the spin lock block in sunxi_mmc_request and so (even if it should never happend) it would have theoretically been possible that some other function would access the variable at the same time as the function. This has been changed now and the function is using local variables outside the lock and copys the value over during the lock phase. Signed-off-by: David Lanzendörfer Reported-by: 李想 --- drivers/mmc/host/sunxi-mmc.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c index 15cb8b7..25ba321 100644 --- a/drivers/mmc/host/sunxi-mmc.c +++ b/drivers/mmc/host/sunxi-mmc.c @@ -570,6 +570,15 @@ static irqreturn_t sunxi_mmc_handle_manual_stop(int irq, void *dev_id) } dev_err(mmc_dev(host->mmc), "data error, sending stop command\n"); + + /* + * We will never have more than one outstanding request, + * and we do not complete the request until after + * we've cleared host->manual_stop_mrq so we do not need to + * spin lock this function. + * Additionally we have wait states within this function + * so having it in a lock is a very bad idea. + */ sunxi_mmc_send_manual_stop(host, mrq); spin_lock_irqsave(&host->lock, iflags); @@ -766,6 +775,7 @@ static void sunxi_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq) unsigned long iflags; u32 imask = SDXC_INTERRUPT_ERROR_BIT; u32 cmd_val = SDXC_START | (cmd->opcode & 0x3f); + bool wait_dma = host->wait_dma; int ret; /* Check for set_ios errors (should never happen) */ @@ -816,7 +826,7 @@ static void sunxi_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq) if (cmd->data->flags & MMC_DATA_WRITE) cmd_val |= SDXC_WRITE; else - host->wait_dma = true; + wait_dma = true; } else { imask |= SDXC_COMMAND_DONE; } @@ -850,6 +860,7 @@ static void sunxi_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq) } host->mrq = mrq; + host->wait_dma = wait_dma; mmc_writel(host, REG_IMASK, host->sdio_imask | imask); mmc_writel(host, REG_CARG, cmd->arg); mmc_writel(host, REG_CMDR, cmd_val); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/