Clemens Ladisch 96e9694df4 hpet: fix unwanted interrupt due to stale irq status bit ... Jaswinder Singh Rajput wrote: > By executing Documentation/timers/hpet_example.c > > for polling, I requested for 3 iterations but it seems iteration work > for only 2 as first expired time is always very small. > > # ./hpet_example poll /dev/hpet 10 3 > -hpet: executing poll > hpet_poll: info.hi_flags 0x0 > hpet_poll: expired time = 0x13 > hpet_poll: revents = 0x1 > hpet_poll: data 0x1 > hpet_poll: expired time = 0x1868c > hpet_poll: revents = 0x1 > hpet_poll: data 0x1 > hpet_poll: expired time = 0x18645 > hpet_poll: revents = 0x1 > hpet_poll: data 0x1 Clearing the HPET interrupt enable bit disables interrupt generation but does not disable the timer, so the interrupt status bit will still be set when the timer elapses. If another interrupt arrives before the timer has been correctly programmed (due to some other device on the same interrupt line, or CONFIG_DEBUG_SHIRQ), this results in an extra unwanted interrupt event because the status bit is likely to be set from comparator matches that happened before the device was opened. Therefore, we have to ensure that the interrupt status bit is and stays cleared until we actually program the timer. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Reported-by: Jaswinder Singh Rajput <jaswinderlinux@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Cc: Bob Picco <bpicco@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2010-10-26 16:52:11 -07:00
..
agp	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2010-10-24 13:41:39 -07:00
hw_random	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
ip2	Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6	2010-10-22 19:59:04 -07:00
ipmi	ipmi: proper spinlock initialization	2010-10-26 16:52:04 -07:00
mwave	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
pcmcia	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2010-10-24 13:41:39 -07:00
rio	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
tpm	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2010-10-24 13:41:39 -07:00
xilinx_hwicap	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
.gitignore
amiserial.c	tty: icount changeover for other main devices	2010-10-22 10:20:05 -07:00
apm-emulation.c	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2010-10-24 13:41:39 -07:00
applicom.c	drivers: autoconvert trivial BKL users to private mutex	2010-10-05 15:01:04 +02:00
applicom.h
bfin-otp.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
bfin_jtag_comm.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
briq_panel.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
bsr.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
cd1865.h
consolemap.c
cp437.uni
cs5535_gpio.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
cyclades.c	tty: icount changeover for other main devices	2010-10-22 10:20:05 -07:00
defkeymap.c_shipped
defkeymap.map
digi1.h
digiFep1.h
digiPCI.h
ds1302.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
ds1620.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
dsp56k.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
dtlk.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
efirtc.c
epca.c	epca: Kill the big kernel lock	2010-08-10 13:47:40 -07:00
epca.h
epcaconfig.h
generic_nvram.c	drivers: autoconvert trivial BKL users to private mutex	2010-10-05 15:01:04 +02:00
generic_serial.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
genrtc.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
hangcheck-timer.c	Input: sysrq - drop tty argument form handle_sysrq()	2010-08-21 00:34:45 -07:00
hpet.c	hpet: fix unwanted interrupt due to stale irq status bit	2010-10-26 16:52:11 -07:00
hvc_beat.c
hvc_console.c	Input: sysrq - drop tty argument form handle_sysrq()	2010-08-21 00:34:45 -07:00
hvc_console.h
hvc_irq.c
hvc_iseries.c
hvc_iucv.c	[S390] hvc_iucv: do not call iucv_unregister if iucv_register failed	2010-10-25 16:10:17 +02:00
hvc_rtas.c
hvc_tile.c	arch/tile: catch up on various minor cleanups.	2010-07-06 13:42:15 -04:00
hvc_udbg.c
hvc_vio.c
hvc_xen.c
hvcs.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
hvsi.c	Input: sysrq - drop tty argument form handle_sysrq()	2010-08-21 00:34:45 -07:00
i8k.c	drivers: autoconvert trivial BKL users to private mutex	2010-10-05 15:01:04 +02:00
isicom.c	isicom: kill off the BKL	2010-08-10 13:47:40 -07:00
istallion.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
Kconfig	add ttyprintk driver	2010-10-22 10:20:02 -07:00
keyboard.c	Input: add support for large scancodes	2010-09-09 22:00:50 -07:00
lp.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
Makefile	add ttyprintk driver	2010-10-22 10:20:02 -07:00
mbcs.c	drivers: autoconvert trivial BKL users to private mutex	2010-10-05 15:01:04 +02:00
mbcs.h
mem.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
misc.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
mmtimer.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
moxa.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
moxa.h
mspec.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
mxser.c	tty: icount changeover for other main devices	2010-10-22 10:20:05 -07:00
mxser.h
n_gsm.c	drivers/char/n_gsm.c: add missing spin_unlock_irqrestore	2010-08-11 08:59:20 -07:00
n_hdlc.c	tty: replace BKL with a new tty_lock	2010-08-10 13:47:43 -07:00
n_r3964.c	Update broken web addresses in the kernel.	2010-10-18 11:03:14 +02:00
n_tty.c	tty: Add EXTPROC support for LINEMODE	2010-08-10 13:47:39 -07:00
nozomi.c	tty: icount changeover for other main devices	2010-10-22 10:20:05 -07:00
nsc_gpio.c
nvram.c	drivers: autoconvert trivial BKL users to private mutex	2010-10-05 15:01:04 +02:00
nwbutton.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
nwbutton.h
nwflash.c	drivers: autoconvert trivial BKL users to private mutex	2010-10-05 15:01:04 +02:00
pc8736x_gpio.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
ppdev.c	drivers: autoconvert trivial BKL users to private mutex	2010-10-05 15:01:04 +02:00
ps3flash.c	drop unused dentry argument to ->fsync	2010-05-27 22:05:02 -04:00
pty.c	tty: Remove __GFP_NOFAIL from tty_add_file()	2010-10-22 10:19:58 -07:00
ramoops.c	char drivers: RAM oops/panic logger	2010-05-27 09:12:50 -07:00
random.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
raw.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
riscom8.c	riscom8: kill use of lock_kernel	2010-08-10 13:47:40 -07:00
riscom8.h
riscom8_reg.h
rocket.c	rocket: add a mutex_unlock()	2010-08-23 18:17:21 -07:00
rocket.h
rocket_int.h
rtc.c	of/device: Replace struct of_device with struct platform_device	2010-08-06 09:25:50 -06:00
scc.h
scx200_gpio.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
selection.c	tty: remove tty_lock_nested	2010-08-10 13:47:44 -07:00
ser_a2232.c
ser_a2232.h
ser_a2232fw.ax
ser_a2232fw.h
serial167.c	tty: release BTM while sleeping in block_til_ready	2010-08-10 13:47:44 -07:00
snsc.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
snsc.h
snsc_event.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
sonypi.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
specialix.c	tty: release BTM while sleeping in block_til_ready	2010-08-10 13:47:44 -07:00
specialix_io8.h
stallion.c	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2010-10-24 13:41:39 -07:00
sx.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
sx.h
sxboards.h
sxwindow.h
synclink.c	tty: icount changeover for other main devices	2010-10-22 10:20:05 -07:00
synclink_gt.c	tty: icount changeover for other main devices	2010-10-22 10:20:05 -07:00
synclinkmp.c	tty: icount changeover for other main devices	2010-10-22 10:20:05 -07:00
sysrq.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input	2010-10-25 07:59:01 -07:00
tb0219.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
tlclk.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
toshiba.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
tty_audit.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
tty_buffer.c	tty: fix obsolete comment on tty_insert_flip_string_fixed_flag	2010-05-21 09:34:30 -07:00
tty_io.c	tty: Make tiocgicount a handler	2010-10-22 10:20:04 -07:00
tty_ioctl.c	tty: Add EXTPROC support for LINEMODE	2010-08-10 13:47:39 -07:00
tty_ldisc.c	tty: remove tty_lock_nested	2010-08-10 13:47:44 -07:00
tty_mutex.c	tty: implement BTM as mutex instead of BKL	2010-08-10 13:47:44 -07:00
tty_port.c	tty: release BTM while sleeping in block_til_ready	2010-08-10 13:47:44 -07:00
ttyprintk.c	add ttyprintk driver	2010-10-22 10:20:02 -07:00
uv_mmtimer.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
vc_screen.c	vcs: invoke the vt update callback when /dev/vcs* is written to	2010-10-22 10:20:06 -07:00
viotape.c	Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl	2010-10-22 10:52:56 -07:00
virtio_console.c	virtio: console: Disable lseek(2) for port file operations	2010-10-21 17:44:04 +10:30
vme_scc.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
vt.c	vcs: invoke the vt update callback when /dev/vcs* is written to	2010-10-22 10:20:06 -07:00
vt_ioctl.c	Input: use PIT_TICK_RATE in vt beep ioctl	2010-08-28 21:39:09 -07:00