linux/include/asm-generic/rtc.h
Andrew Morton 795d45b22c x86: fix RTC lockdep warning: potential hardirq recursion
After disabling both CONFIG_DEBUG_LOCKING_API_SELFTESTS and netconsole
(using current mainline) I get a login prompt, and also...

[    5.181668] SELinux: policy loaded with handle_unknown=deny
[    5.183315] type=1403 audit(1202100038.157:3): policy loaded auid=4294967295 ses=4294967295
[    5.822073] SELinux: initialized (dev usbfs, type usbfs), uses genfs_contexts
[    7.819146] ------------[ cut here ]------------
[    7.819146] WARNING: at kernel/lockdep.c:2033 trace_hardirqs_on+0x9b/0x10d()
[    7.819146] Modules linked in: generic ext3 jbd ide_disk ide_core
[    7.819146] Pid: 399, comm: hwclock Not tainted 2.6.24 #4
[    7.819146]  [<c011d140>] warn_on_slowpath+0x41/0x51
[    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[    7.819146]  [<c013770c>] ? check_usage_forwards+0x19/0x3b
[    7.819146]  [<c01390c4>] ? __lock_acquire+0xac3/0xb0b
[    7.819146]  [<c0108c98>] ? native_sched_clock+0x8b/0x9f
[    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[    7.819146]  [<c030ca6c>] ? _spin_unlock_irq+0x22/0x42
[    7.819146]  [<c013848b>] trace_hardirqs_on+0x9b/0x10d
[    7.819146]  [<c030ca6c>] _spin_unlock_irq+0x22/0x42
[    7.819146]  [<c011481e>] hpet_rtc_interrupt+0xdf/0x290
[    7.819146]  [<c014ea90>] handle_IRQ_event+0x1a/0x46
[    7.819146]  [<c014f8ea>] handle_edge_irq+0xbe/0xff
[    7.819146]  [<c0106e08>] do_IRQ+0x6d/0x84
[    7.819146]  [<c0105596>] common_interrupt+0x2e/0x34
[    7.819146]  [<c013007b>] ? ktime_get_ts+0x8/0x3f
[    7.819146]  [<c0139420>] ? lock_release+0x167/0x16f
[    7.819146]  [<c017974a>] ? core_sys_select+0x2c/0x327
[    7.819146]  [<c0179792>] core_sys_select+0x74/0x327
[    7.819146]  [<c0108c98>] ? native_sched_clock+0x8b/0x9f
[    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[    7.819146]  [<c030ca6c>] ? _spin_unlock_irq+0x22/0x42
[    7.819146]  [<c01384d6>] ? trace_hardirqs_on+0xe6/0x10d
[    7.819146]  [<c030ca77>] ? _spin_unlock_irq+0x2d/0x42
[    7.819146]  [<c023b437>] ? rtc_do_ioctl+0x11b/0x677
[    7.819146]  [<c01c487e>] ? inode_has_perm+0x5e/0x68
[    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[    7.819146]  [<c0108c98>] ? native_sched_clock+0x8b/0x9f
[    7.819146]  [<c01c490b>] ? file_has_perm+0x83/0x8c
[    7.819146]  [<c023ba08>] ? rtc_ioctl+0xf/0x11
[    7.819146]  [<c017898d>] ? do_ioctl+0x55/0x67
[    7.819146]  [<c0179d15>] sys_select+0x93/0x163
[    7.819146]  [<c0104b39>] ? sysenter_past_esp+0x9a/0xa5
[    7.819146]  [<c0104afe>] sysenter_past_esp+0x5f/0xa5
[    7.819146]  =======================
[    7.819146] ---[ end trace 96540ca301ffb84c ]---
[    7.819210] rtc: lost 6 interrupts
[    7.870668] type=1400 audit(1202128840.794:4): avc:  denied  { audit_write } for  pid=399 comm="hwclock" capability=29 scontext=system_u:system_r:hwclock_t:s0 tcontext=system_u:system_r:hwclock_t:s0 tclass=capability
[    9.538866] input: PC Speaker as /class/input/input5

Because hpet_rtc_interrupt()'s call to get_rtc_time() ends up
resolving to include/asm-generic/rtc.h's (hilariously inlined)
get_rtc_time(), which does spin_unlock_irq() from hard IRQ context.

The obvious patch fixes it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-04 16:48:10 +01:00

217 lines
5.2 KiB
C

/*
* include/asm-generic/rtc.h
*
* Author: Tom Rini <trini@mvista.com>
*
* Based on:
* drivers/char/rtc.c
*
* Please read the COPYING file for all license details.
*/
#ifndef __ASM_RTC_H__
#define __ASM_RTC_H__
#ifdef __KERNEL__
#include <linux/mc146818rtc.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#define RTC_PIE 0x40 /* periodic interrupt enable */
#define RTC_AIE 0x20 /* alarm interrupt enable */
#define RTC_UIE 0x10 /* update-finished interrupt enable */
/* some dummy definitions */
#define RTC_BATT_BAD 0x100 /* battery bad */
#define RTC_SQWE 0x08 /* enable square-wave output */
#define RTC_DM_BINARY 0x04 /* all time/date values are BCD if clear */
#define RTC_24H 0x02 /* 24 hour mode - else hours bit 7 means pm */
#define RTC_DST_EN 0x01 /* auto switch DST - works f. USA only */
/*
* Returns true if a clock update is in progress
*/
static inline unsigned char rtc_is_updating(void)
{
unsigned char uip;
unsigned long flags;
spin_lock_irqsave(&rtc_lock, flags);
uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
spin_unlock_irqrestore(&rtc_lock, flags);
return uip;
}
static inline unsigned int get_rtc_time(struct rtc_time *time)
{
unsigned long uip_watchdog = jiffies;
unsigned char ctrl;
unsigned long flags;
#ifdef CONFIG_MACH_DECSTATION
unsigned int real_year;
#endif
/*
* read RTC once any update in progress is done. The update
* can take just over 2ms. We wait 10 to 20ms. There is no need to
* to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
* If you need to know *exactly* when a second has started, enable
* periodic update complete interrupts, (via ioctl) and then
* immediately read /dev/rtc which will block until you get the IRQ.
* Once the read clears, read the RTC time (again via ioctl). Easy.
*/
if (rtc_is_updating() != 0)
while (jiffies - uip_watchdog < 2*HZ/100) {
barrier();
cpu_relax();
}
/*
* Only the values that we read from the RTC are set. We leave
* tm_wday, tm_yday and tm_isdst untouched. Even though the
* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
* by the RTC when initially set to a non-zero value.
*/
spin_lock_irqsave(&rtc_lock, flags);
time->tm_sec = CMOS_READ(RTC_SECONDS);
time->tm_min = CMOS_READ(RTC_MINUTES);
time->tm_hour = CMOS_READ(RTC_HOURS);
time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
time->tm_mon = CMOS_READ(RTC_MONTH);
time->tm_year = CMOS_READ(RTC_YEAR);
#ifdef CONFIG_MACH_DECSTATION
real_year = CMOS_READ(RTC_DEC_YEAR);
#endif
ctrl = CMOS_READ(RTC_CONTROL);
spin_unlock_irqrestore(&rtc_lock, flags);
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
BCD_TO_BIN(time->tm_sec);
BCD_TO_BIN(time->tm_min);
BCD_TO_BIN(time->tm_hour);
BCD_TO_BIN(time->tm_mday);
BCD_TO_BIN(time->tm_mon);
BCD_TO_BIN(time->tm_year);
}
#ifdef CONFIG_MACH_DECSTATION
time->tm_year += real_year - 72;
#endif
/*
* Account for differences between how the RTC uses the values
* and how they are defined in a struct rtc_time;
*/
if (time->tm_year <= 69)
time->tm_year += 100;
time->tm_mon--;
return RTC_24H;
}
/* Set the current date and time in the real time clock. */
static inline int set_rtc_time(struct rtc_time *time)
{
unsigned long flags;
unsigned char mon, day, hrs, min, sec;
unsigned char save_control, save_freq_select;
unsigned int yrs;
#ifdef CONFIG_MACH_DECSTATION
unsigned int real_yrs, leap_yr;
#endif
yrs = time->tm_year;
mon = time->tm_mon + 1; /* tm_mon starts at zero */
day = time->tm_mday;
hrs = time->tm_hour;
min = time->tm_min;
sec = time->tm_sec;
if (yrs > 255) /* They are unsigned */
return -EINVAL;
spin_lock_irqsave(&rtc_lock, flags);
#ifdef CONFIG_MACH_DECSTATION
real_yrs = yrs;
leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) ||
!((yrs + 1900) % 400));
yrs = 72;
/*
* We want to keep the year set to 73 until March
* for non-leap years, so that Feb, 29th is handled
* correctly.
*/
if (!leap_yr && mon < 3) {
real_yrs--;
yrs = 73;
}
#endif
/* These limits and adjustments are independent of
* whether the chip is in binary mode or not.
*/
if (yrs > 169) {
spin_unlock_irqrestore(&rtc_lock, flags);
return -EINVAL;
}
if (yrs >= 100)
yrs -= 100;
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
|| RTC_ALWAYS_BCD) {
BIN_TO_BCD(sec);
BIN_TO_BCD(min);
BIN_TO_BCD(hrs);
BIN_TO_BCD(day);
BIN_TO_BCD(mon);
BIN_TO_BCD(yrs);
}
save_control = CMOS_READ(RTC_CONTROL);
CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
#ifdef CONFIG_MACH_DECSTATION
CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
#endif
CMOS_WRITE(yrs, RTC_YEAR);
CMOS_WRITE(mon, RTC_MONTH);
CMOS_WRITE(day, RTC_DAY_OF_MONTH);
CMOS_WRITE(hrs, RTC_HOURS);
CMOS_WRITE(min, RTC_MINUTES);
CMOS_WRITE(sec, RTC_SECONDS);
CMOS_WRITE(save_control, RTC_CONTROL);
CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
}
static inline unsigned int get_rtc_ss(void)
{
struct rtc_time h;
get_rtc_time(&h);
return h.tm_sec;
}
static inline int get_rtc_pll(struct rtc_pll_info *pll)
{
return -EINVAL;
}
static inline int set_rtc_pll(struct rtc_pll_info *pll)
{
return -EINVAL;
}
#endif /* __KERNEL__ */
#endif /* __ASM_RTC_H__ */