Messages in this thread | | | Date | Tue, 19 Aug 2008 00:53:20 -0700 | From | Andrew Morton <> | Subject | Re: [BUG] rtc uie emulation deadlocks |
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On Mon, 11 Aug 2008 14:43:39 +0100 Russell King <rmk+lkml@arm.linux.org.uk> wrote:
> With CONFIG_RTC_INTF_DEV_UIE_EMUL=y, hwclock deadlocks in rtc_read_time > due to: > > static long rtc_dev_ioctl(struct file *file, > unsigned int cmd, unsigned long arg) > { > err = mutex_lock_interruptible(&rtc->ops_lock); > if (err) > return err; > ... > switch (cmd) { > #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL > case RTC_UIE_OFF: > clear_uie(rtc); > break; > > case RTC_UIE_ON: > err = set_uie(rtc); > #endif > } > > static int set_uie(struct rtc_device *rtc) > { > err = rtc_read_time(rtc, &tm); > ... > > int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm) > { > err = mutex_lock_interruptible(&rtc->ops_lock); > > So we try to take the same lock twice... Not good. > > The locking looks a rather random in there, so I'm not going to try to > create a patch. >
Looks like this was caused by
commit 5ad31a575157147b43fa84ef1e21471661653878 Author: David Brownell <david-b@pacbell.net> Date: Wed Jul 23 21:30:33 2008 -0700
rtc: remove BKL for ioctl()
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