1 files changed, 39 insertions, 3 deletions

diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 671b14ec28bb..f4e5f0040ff7 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -277,12 +277,48 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 
                 alarm.enabled = 0;
                 alarm.pending = 0;
-                alarm.time.tm_mday = -1;
-                alarm.time.tm_mon = -1;
-                alarm.time.tm_year = -1;
                 alarm.time.tm_wday = -1;
                 alarm.time.tm_yday = -1;
                 alarm.time.tm_isdst = -1;
+
+                /* RTC_ALM_SET alarms may be up to 24 hours in the future.
+                 * Rather than expecting every RTC to implement "don't care"
+                 * for day/month/year fields, just force the alarm to have
+                 * the right values for those fields.
+                 *
+                 * RTC_WKALM_SET should be used instead.  Not only does it
+                 * eliminate the need for a separate RTC_AIE_ON call, it
+                 * doesn't have the "alarm 23:59:59 in the future" race.
+                 *
+                 * NOTE:  some legacy code may have used invalid fields as
+                 * wildcards, exposing hardware "periodic alarm" capabilities.
+                 * Not supported here.
+                 */
+                {
+                        unsigned long now, then;
+
+                        err = rtc_read_time(rtc, &tm);
+                        if (err < 0)
+                                return err;
+                        rtc_tm_to_time(&tm, &now);
+
+                        alarm.time.tm_mday = tm.tm_mday;
+                        alarm.time.tm_mon = tm.tm_mon;
+                        alarm.time.tm_year = tm.tm_year;
+                        err  = rtc_valid_tm(&alarm.time);
+                        if (err < 0)
+                                return err;
+                        rtc_tm_to_time(&alarm.time, &then);
+
+                        /* alarm may need to wrap into tomorrow */
+                        if (then < now) {
+                                rtc_time_to_tm(now + 24 * 60 * 60, &tm);
+                                alarm.time.tm_mday = tm.tm_mday;
+                                alarm.time.tm_mon = tm.tm_mon;
+                                alarm.time.tm_year = tm.tm_year;
+                        }
+                }
+
                 err = rtc_set_alarm(rtc, &alarm);
                 break;