John Stultz 6b43ae8a61 ntp: Fix leap-second hrtimer livelock ... Since commit 7dffa3c673 the ntp subsystem has used an hrtimer for triggering the leapsecond adjustment. However, this can cause a potential livelock. Thomas diagnosed this as the following pattern: CPU 0 CPU 1 do_adjtimex() spin_lock_irq(&ntp_lock); process_adjtimex_modes(); timer_interrupt() process_adj_status(); do_timer() ntp_start_leap_timer(); write_lock(&xtime_lock); hrtimer_start(); update_wall_time(); hrtimer_reprogram(); ntp_tick_length() tick_program_event() spin_lock(&ntp_lock); clockevents_program_event() ktime_get() seq = req_seqbegin(xtime_lock); This patch tries to avoid the problem by reverting back to not using an hrtimer to inject leapseconds, and instead we handle the leapsecond processing in the second_overflow() function. The downside to this change is that on systems that support highres timers, the leap second processing will occur on a HZ tick boundary, (ie: ~1-10ms, depending on HZ) after the leap second instead of possibly sooner (~34us in my tests w/ x86_64 lapic). This patch applies on top of tip/timers/core. CC: Sasha Levin <levinsasha928@gmail.com> CC: Thomas Gleixner <tglx@linutronix.de> Reported-by: Sasha Levin <levinsasha928@gmail.com> Diagnoised-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>		2012-03-22 19:43:43 -07:00
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acpi	Merge branches 'atomicio-apei', 'hotplug', 'sony-nvs-nosave' and 'thermal-netlink' into release	2012-01-23 19:47:06 -05:00
asm-generic	lib: add NO_GENERIC_PCI_IOPORT_MAP	2012-01-31 23:19:47 +02:00
crypto
drm	drm: Fix authentication kernel crash	2012-01-25 09:27:45 +00:00
keys
linux	ntp: Fix leap-second hrtimer livelock	2012-03-22 19:43:43 -07:00
math-emu
media
misc
mtd
net	netprio_cgroup: fix wrong memory access when NETPRIO_CGROUP=m	2012-02-10 15:08:57 -05:00
pcmcia
rdma
rxrpc
scsi
sound	Merge branch 'fix/asoc' into for-linus	2012-01-31 15:13:14 +01:00
target	target: Change target_submit_cmd() to return void	2012-02-07 06:41:04 +00:00
trace	writeback: fix dereferencing NULL bdi->dev on trace_writeback_queue	2012-02-06 11:17:25 +08:00
video	fbdev fixes for 3.3	2012-02-07 15:54:02 -08:00
xen
Kbuild