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Wed, 28 Mar 2018 22:18:24 -0400 Received: from mail-pg0-f68.google.com ([74.125.83.68]:33776 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750795AbeC2CSX (ORCPT ); Wed, 28 Mar 2018 22:18:23 -0400 X-Google-Smtp-Source: AIpwx483qtcTh8EZRuGrovj2vDPjFeAtRaM3XwZx1BWIG+7v/3jWJTV1OCvNjVaR52AP3XH99CLtlg== Date: Thu, 29 Mar 2018 10:18:06 +0800 From: Shawn Guo To: Bryan O'Donoghue Cc: alexandre.belloni@free-electrons.com, linux-kernel@vger.kernel.org, a.zummo@towertech.it, Pan Bian , Guy Shapiro , Stefan Agner , Frank Li , linux-rtc@vger.kernel.org, "# v3 . 16+" Subject: Re: [RESEND] [PATCH] rtc: snvs: Fix usage of snvs_rtc_enable Message-ID: <20180329021803.GI27302@dragon> References: <1522264445-2398-1-git-send-email-pure.logic@nexus-software.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522264445-2398-1-git-send-email-pure.logic@nexus-software.ie> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Mar 28, 2018 at 08:14:05PM +0100, Bryan O'Donoghue wrote: > commit 179a502f8c46 ("rtc: snvs: add Freescale rtc-snvs driver") introduces > the SNVS RTC driver with a function snvs_rtc_enable(). > > snvs_rtc_enable() can return an error on the enable path however this > driver does not currently trap that failure on the probe() path and > consequently if enabling the RTC fails we encounter a later error spinning > forever in rtc_write_sync_lp(). > > [ 36.093481] [] (__irq_svc) from [] (_raw_spin_unlock_irqrestore+0x34/0x44) > [ 36.102122] [] (_raw_spin_unlock_irqrestore) from [] (regmap_read+0x4c/0x5c) > [ 36.110938] [] (regmap_read) from [] (rtc_write_sync_lp+0x6c/0x98) > [ 36.118881] [] (rtc_write_sync_lp) from [] (snvs_rtc_alarm_irq_enable+0x40/0x4c) > [ 36.128041] [] (snvs_rtc_alarm_irq_enable) from [] (rtc_timer_do_work+0xd8/0x1a8) > [ 36.137291] [] (rtc_timer_do_work) from [] (process_one_work+0x28c/0x76c) > [ 36.145840] [] (process_one_work) from [] (worker_thread+0x34/0x58c) > [ 36.153961] [] (worker_thread) from [] (kthread+0x138/0x150) > [ 36.161388] [] (kthread) from [] (ret_from_fork+0x14/0x20) > [ 36.168635] rcu_sched kthread starved for 2602 jiffies! g496 c495 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 > [ 36.178564] rcu_sched R running task 0 8 2 0x00000000 > [ 36.185664] [] (__schedule) from [] (schedule+0x3c/0xa0) > [ 36.192739] [] (schedule) from [] (schedule_timeout+0x78/0x4e0) > [ 36.200422] [] (schedule_timeout) from [] (rcu_gp_kthread+0x648/0x1864) > [ 36.208800] [] (rcu_gp_kthread) from [] (kthread+0x138/0x150) > [ 36.216309] [] (kthread) from [] (ret_from_fork+0x14/0x20) > > This patch fixes by parsing the result of rtc_write_sync_lp() and > propagating both in the probe and elsewhere. If the RTC doesn't start we > don't proceed loading the driver and don't get into this loop mess later > on. > > Fixes: 179a502f8c46 ("rtc: snvs: add Freescale rtc-snvs driver") > > Signed-off-by: Bryan O'Donoghue > Cc: a.zummo@towertech.it > Cc: alexandre.belloni@free-electrons.com > Cc: Pan Bian > Cc: Guy Shapiro > Cc: Stefan Agner > Cc: Frank Li > Cc: Shawn Guo Acked-by: Shawn Guo