From: Josh Poimboeuf Date: Mon, 7 Mar 2016 15:03:02 +0000 (-0600) Subject: rtc: ds1685: actually spin forever in poweroff error path X-Git-Tag: v4.6-rc1~144^2~5 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=361c6ed6b153;p=karo-tx-linux.git rtc: ds1685: actually spin forever in poweroff error path objtool reports the following warnings: drivers/rtc/rtc-ds1685.o: warning: objtool: ds1685_rtc_work_queue()+0x0: duplicate frame pointer save drivers/rtc/rtc-ds1685.o: warning: objtool: ds1685_rtc_work_queue()+0x3: duplicate frame pointer setup drivers/rtc/rtc-ds1685.o: warning: objtool: ds1685_rtc_work_queue()+0x0: frame pointer state mismatch The warning message needs to be improved, but what it really means in this case is that ds1685_rtc_poweroff() has a possible code path where it can actually fall through to the next function in the object code, ds1685_rtc_work_queue(). The bug is caused by the use of the unreachable() macro in a place which is actually reachable. That causes gcc to assume that the printk() immediately before the unreachable() macro never returns, when in fact it does. So gcc places the printk() at the very end of the function's object code. When the printk() returns, the next function starts executing. The surrounding comment and printk message state that the code should spin forever, which explains the unreachable() statement. However the actual spin code is missing. Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Signed-off-by: Alexandre Belloni --- diff --git a/drivers/rtc/rtc-ds1685.c b/drivers/rtc/rtc-ds1685.c index 08e0ff8c786a..1e6cfc84b1f6 100644 --- a/drivers/rtc/rtc-ds1685.c +++ b/drivers/rtc/rtc-ds1685.c @@ -2161,6 +2161,7 @@ ds1685_rtc_poweroff(struct platform_device *pdev) /* Check for valid RTC data, else, spin forever. */ if (unlikely(!pdev)) { pr_emerg("platform device data not available, spinning forever ...\n"); + while(1); unreachable(); } else { /* Get the rtc data. */