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Steps to reproduce the problem: 1) Enable RTC wake-up option in BIOS Setup 2) Issue one of these commands in the OS: "poweroff" or "shutdown -h now" 3) System will shut down and then reboot automatically Root-cause of the issue: 1) During the shutdown process, the hwclock utility is used to save the system clock to hardware clock (RTC). 2) The hwclock utility invokes ioctl() with RTC_UIE_ON. The kernel configures the RTC alarm for the periodic interrupt (every 1 second). 3) The hwclock uitlity closes the /dev/rtc0 device, and the kernel disables the RTC alarm irq (AIE bit of Register B) via ioctl() with RTC_UIE_OFF. But, the configured alarm time is the current_time + 1. 4) After the next 1 second is elapsed, the AF (alarm interrupt flag) of Register C is set. 5) The S5 handler in BIOS is invoked to configure alarm registers (enable AIE bit and configure alarm date/time). But, BIOS does not clear the previous interrupt status during alarm configuration. Therefore, "AF=AIE=1" causes the rtc device to trigger an interrupt. 6) So, the machine reboots automatically right after shutdown. This patch cancels the alarm timer if the following condictions are met (suggested by Alexandre): 1) The configured alarm time is equal to current_time + 1 seconds. 2) The AIE timer is not in use. The member 'alarm_expires' is introduced in struct cmos_rtc because of the following reasons: 1) The configured alarm time can be retrieved from cmos_read_alarm(), but we need to take the 'wrapped timestamp' and 'time rollover' into consideration. The function __rtc_read_alarm() eliminates the concerns. To avoid the duplicated code in the lower level RTC driver, invoking __rtc_read_alarm from the lower level RTC driver is not encouraged. Moreover, the compilation error 'the undefined __rtc_read_alarm" is observed if the lower level RTC driver is compiled as a kernel module. 2) The uie_rtctimer.node.expires and aie_timer.node.expires can be retrieved for the configured alarm time. But, the problem is that either of them might configure the CMOS alarm time. We cannot make sure UIE timer or AIE tiemr configured the CMOS alarm time before. (uie_rtctimer or aie_timer is enabled and then is disabled). 3) The patch introduces the member 'alarm_expires' to keep the newly configured alarm time, so the above-mentioned concerns can be eliminated. The issue goes away after 20-time shutdown tests. Signed-off-by: Adrian Huang <ahuang12@lenovo.com> Tested-by: Egbert Eich <eich@suse.de> Tested-by: Diego Ercolani <diego.ercolani@gmail.com> Cc: Borislav Petkov <bp@suse.de> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> |
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| accessibility | ||
| acpi | ||
| amba | ||
| android | ||
| ata | ||
| atm | ||
| auxdisplay | ||
| base | ||
| bcma | ||
| block | ||
| bluetooth | ||
| bus | ||
| cdrom | ||
| char | ||
| clk | ||
| clocksource | ||
| connector | ||
| cpufreq | ||
| cpuidle | ||
| crypto | ||
| dca | ||
| devfreq | ||
| dio | ||
| dma | ||
| dma-buf | ||
| edac | ||
| eisa | ||
| extcon | ||
| firewire | ||
| firmware | ||
| fmc | ||
| gpio | ||
| gpu | ||
| hid | ||
| hsi | ||
| hv | ||
| hwmon | ||
| hwspinlock | ||
| hwtracing/coresight | ||
| i2c | ||
| ide | ||
| idle | ||
| iio | ||
| infiniband | ||
| input | ||
| iommu | ||
| ipack | ||
| irqchip | ||
| isdn | ||
| leds | ||
| lguest | ||
| macintosh | ||
| mailbox | ||
| mcb | ||
| md | ||
| media | ||
| memory | ||
| memstick | ||
| message | ||
| mfd | ||
| misc | ||
| mmc | ||
| mtd | ||
| net | ||
| nfc | ||
| ntb | ||
| nubus | ||
| nvdimm | ||
| nvmem | ||
| of | ||
| oprofile | ||
| parisc | ||
| parport | ||
| pci | ||
| pcmcia | ||
| perf | ||
| phy | ||
| pinctrl | ||
| platform | ||
| pnp | ||
| power | ||
| powercap | ||
| pps | ||
| ps3 | ||
| ptp | ||
| pwm | ||
| rapidio | ||
| ras | ||
| regulator | ||
| remoteproc | ||
| reset | ||
| rpmsg | ||
| rtc | ||
| s390 | ||
| sbus | ||
| scsi | ||
| sfi | ||
| sh | ||
| sn | ||
| soc | ||
| spi | ||
| spmi | ||
| ssb | ||
| staging | ||
| target | ||
| tc | ||
| thermal | ||
| thunderbolt | ||
| tty | ||
| uio | ||
| usb | ||
| uwb | ||
| vfio | ||
| vhost | ||
| video | ||
| virt | ||
| virtio | ||
| vlynq | ||
| vme | ||
| w1 | ||
| watchdog | ||
| xen | ||
| zorro | ||
| Kconfig | ||
| Makefile | ||