Since commit f44f7f9 (RTC: Initialize kernel state from RTC)
rtc_device_register reads the programmed alarm. As reading the alarm needs to take the lock, release it before calling rtc_device_register. This fixes a deadlock during boot: INFO: task swapper:1 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. swapper D c02b175c 0 1 0 0x00000000 [<c02b175c>] (schedule+0x304/0x4f4) from [<c02b25a8>] (__mutex_lock_slowpath+0x7c/0x110) [<c02b25a8>] (__mutex_lock_slowpath+0x7c/0x110) from [<c020b4cc>] (mc13xxx_rtc_read_time+0x1c/0x118) [<c020b4cc>] (mc13xxx_rtc_read_time+0x1c/0x118) from [<c0208f04>] (__rtc_read_time+0x58/0x5c) [<c0208f04>] (__rtc_read_time+0x58/0x5c) from [<c0209508>] (rtc_read_time+0x30/0x48) [<c0209508>] (rtc_read_time+0x30/0x48) from [<c0209dd4>] (__rtc_read_alarm+0x1c/0x290) [<c0209dd4>] (__rtc_read_alarm+0x1c/0x290) from [<c0208d58>] (rtc_device_register+0x150/0x27c) [<c0208d58>] (rtc_device_register+0x150/0x27c) from [<c02b0b74>] (mc13xxx_rtc_probe+0x128/0x17c) [<c02b0b74>] (mc13xxx_rtc_probe+0x128/0x17c) from [<c01d5280>] (platform_drv_probe+0x1c/0x24) [<c01d5280>] (platform_drv_probe+0x1c/0x24) from [<c01d3e58>] (driver_probe_device+0x80/0x1a8) [<c01d3e58>] (driver_probe_device+0x80/0x1a8) from [<c01d400c>] (__driver_attach+0x8c/0x90) [<c01d400c>] (__driver_attach+0x8c/0x90) from [<c01d3654>] (bus_for_each_dev+0x60/0x8c) [<c01d3654>] (bus_for_each_dev+0x60/0x8c) from [<c01d2f6c>] (bus_add_driver+0x180/0x248) [<c01d2f6c>] (bus_add_driver+0x180/0x248) from [<c01d4664>] (driver_register+0x70/0x15c) [<c01d4664>] (driver_register+0x70/0x15c) from [<c01d5700>] (platform_driver_probe+0x18/0x98) [<c01d5700>] (platform_driver_probe+0x18/0x98) from [<c00273a8>] (do_one_initcall+0x2c/0x168) [<c00273a8>] (do_one_initcall+0x2c/0x168) from [<c00083ac>] (kernel_init+0xa0/0x150) [<c00083ac>] (kernel_init+0xa0/0x150) from [<c0033ff8>] (kernel_thread_exit+0x0/0x8) Reported-by: Vagrant Cascadian <vagr...@debian.org> Signed-off-by: Uwe Kleine-König <u.kleine-koe...@pengutronix.de> Closes: http://bugs.debian.org/625804 --- Hello Arnaud, On Mon, Apr 04, 2011 at 04:52:54AM -0000, Arnaud Patard wrote: > Index: imx-test/drivers/rtc/rtc-mc13xxx.c > =================================================================== > --- imx-test.orig/drivers/rtc/rtc-mc13xxx.c > +++ imx-test/drivers/rtc/rtc-mc13xxx.c > @@ -349,8 +349,13 @@ static int __devinit mc13xxx_rtc_probe(s > if (ret) > goto err_alarm_irq_request; > > + mc13xxx_unlock(mc13xxx); > + > priv->rtc = rtc_device_register(pdev->name, > &pdev->dev, &mc13xxx_rtc_ops, THIS_MODULE); > + > + mc13xxx_lock(mc13xxx); > + > if (IS_ERR(priv->rtc)) { > ret = PTR_ERR(priv->rtc); the patch below is a bit better as it doesn't take the lock in the likely case that rtc_device_register succeeds. Best regards Uwe diff --git a/drivers/rtc/rtc-mc13xxx.c b/drivers/rtc/rtc-mc13xxx.c index c5ac037..a1a278b 100644 --- a/drivers/rtc/rtc-mc13xxx.c +++ b/drivers/rtc/rtc-mc13xxx.c @@ -349,11 +349,15 @@ static int __devinit mc13xxx_rtc_probe(struct platform_device *pdev) if (ret) goto err_alarm_irq_request; + mc13xxx_unlock(mc13xxx); + priv->rtc = rtc_device_register(pdev->name, &pdev->dev, &mc13xxx_rtc_ops, THIS_MODULE); if (IS_ERR(priv->rtc)) { ret = PTR_ERR(priv->rtc); + mc13xxx_lock(mc13xxx); + mc13xxx_irq_free(mc13xxx, MC13XXX_IRQ_TODA, priv); err_alarm_irq_request: @@ -365,12 +369,12 @@ err_reset_irq_status: mc13xxx_irq_free(mc13xxx, MC13XXX_IRQ_RTCRST, priv); err_reset_irq_request: + mc13xxx_unlock(mc13xxx); + platform_set_drvdata(pdev, NULL); kfree(priv); } - mc13xxx_unlock(mc13xxx); - return ret; } -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org