Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751489AbbKZL4M (ORCPT ); Thu, 26 Nov 2015 06:56:12 -0500 Received: from mail-yk0-f169.google.com ([209.85.160.169]:36390 "EHLO mail-yk0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751071AbbKZL4J (ORCPT ); Thu, 26 Nov 2015 06:56:09 -0500 MIME-Version: 1.0 In-Reply-To: <1448506309-18163-1-git-send-email-chaotian.jing@mediatek.com> References: <1448506309-18163-1-git-send-email-chaotian.jing@mediatek.com> Date: Thu, 26 Nov 2015 12:56:08 +0100 Message-ID: Subject: Re: [PATCH] mmc: core: fix __mmc_switch timeout caused by preempt From: Ulf Hansson To: Chaotian Jing Cc: Matthias Brugger , Stephen Boyd , Adrian Hunter , Minda Chen , linux-mmc , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , linux-mediatek@lists.infradead.org, srv_heupstream Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3825 Lines: 97 On 26 November 2015 at 03:51, Chaotian Jing wrote: > there is a time window between __mmc_send_status() and time_afer(), > on some eMMC chip, the timeout_ms is only 10ms, if this thread was > scheduled out during this period, then, even card has already changes > to transfer state by the result of CMD13, this part of code also treat > it to timeout error. > So, need calculate timeout first, then call __mmc_send_status(), if > already timeout and card still in programing state, then treat it to > the real timeout error. > > Signed-off-by: Chaotian Jing > --- > drivers/mmc/core/mmc_ops.c | 23 ++++++++++++++--------- > 1 file changed, 14 insertions(+), 9 deletions(-) > > diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c > index 1f44426..0add634 100644 > --- a/drivers/mmc/core/mmc_ops.c > +++ b/drivers/mmc/core/mmc_ops.c > @@ -489,6 +489,7 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value, > unsigned long timeout; > u32 status = 0; > bool use_r1b_resp = use_busy_signal; > + bool expired = false; No need to assign an initial value. > > mmc_retune_hold(host); > > @@ -544,10 +545,22 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value, > /* Must check status to be sure of no errors. */ > timeout = jiffies + msecs_to_jiffies(timeout_ms); > do { > + /* Timeout if the device never leaves the program state. Please start mutli-row comment with an empty line. > + * must check it firstly to avoid problem caused by preempt. Please rephrase this to: Due to the possibility of being preempted after sending the status command, check the expiration time first. > + */ > + expired = time_after(jiffies, timeout); I think we can move this inside the below "if (send_status) {" .. but of course before sending the status command. > + > if (send_status) { > err = __mmc_send_status(card, &status, ignore_crc); > - if (err) > + if (err) { > goto out; > + } else if (expired && You may use a new "if" statement instead of an "else if", due to the above "goto out". > + R1_CURRENT_STATE(status) == R1_STATE_PRG) { > + pr_err("%s: Card stuck in programming state! %s\n", > + mmc_hostname(host), __func__); > + err = -ETIMEDOUT; > + goto out; > + } > } > if ((host->caps & MMC_CAP_WAIT_WHILE_BUSY) && use_r1b_resp) > break; > @@ -563,14 +576,6 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value, > mmc_delay(timeout_ms); > goto out; > } > - > - /* Timeout if the device never leaves the program state. */ > - if (time_after(jiffies, timeout)) { > - pr_err("%s: Card stuck in programming state! %s\n", > - mmc_hostname(host), __func__); > - err = -ETIMEDOUT; > - goto out; > - } > } while (R1_CURRENT_STATE(status) == R1_STATE_PRG); > > err = mmc_switch_status_error(host, status); > -- > 1.8.1.1.dirty > Kind regards Uffe -- 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/