19 Mar, 2014
1 commit
-
On Sparc and S390 the removal of irq.h from kernel_stat.h causes:
kernel/softirq.c:774:9: error: 'NR_IRQS_LEGACY' undeclared
Reported-by: Peter Zijlstra
Signed-off-by: Thomas Gleixner
01 Feb, 2014
1 commit
-
Pull timer/dynticks updates from Ingo Molnar:
"This tree contains misc dynticks updates: a fix and three cleanups"* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/nohz: Fix overflow error in scheduler_tick_max_deferment()
nohz_full: fix code style issue of tick_nohz_full_stop_tick
nohz: Get timekeeping max deferment outside jiffies_lock
tick: Rename tick_check_idle() to tick_irq_enter()
28 Jan, 2014
3 commits
-
Reduce data size a little.
Reduce checkpatch noise.$ size kernel/softirq.o*
text data bss dec hex filename
11554 6013 4008 21575 5447 kernel/softirq.o.new
11474 6093 4008 21575 5447 kernel/softirq.o.oldSigned-off-by: Joe Perches
Cc: Frederic Weisbecker
Cc: Ingo Molnar
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Use a more current logging style.
Signed-off-by: Joe Perches
Cc: Frederic Weisbecker
Cc: Ingo Molnar
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Possible speed improvement of __do_softirq() by using ffs() instead of
using a while loop with an & 1 test then single bit shift.Signed-off-by: Joe Perches
Cc: Frederic Weisbecker
Cc: Ingo Molnar
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Jan, 2014
1 commit
-
…eric/linux-dynticks into timers/urgent
Pull dynticks cleanups from Frederic Weisbecker.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
21 Jan, 2014
2 commits
-
Pull timer changes from Ingo Molnar:
- ARM clocksource/clockevent improvements and fixes
- generic timekeeping updates: TAI fixes/improvements, cleanups
- Posix cpu timer cleanups and improvements
- dynticks updates: full dynticks bugfixes, optimizations and cleanups* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
clocksource: Timer-sun5i: Switch to sched_clock_register()
timekeeping: Remove comment that's mostly out of date
rtc-cmos: Add an alarm disable quirk
timekeeper: fix comment typo for tk_setup_internals()
timekeeping: Fix missing timekeeping_update in suspend path
timekeeping: Fix CLOCK_TAI timer/nanosleep delays
tick/timekeeping: Call update_wall_time outside the jiffies lock
timekeeping: Avoid possible deadlock from clock_was_set_delayed
timekeeping: Fix potential lost pv notification of time change
timekeeping: Fix lost updates to tai adjustment
clocksource: sh_cmt: Add clk_prepare/unprepare support
clocksource: bcm_kona_timer: Remove unused bcm_timer_ids
clocksource: vt8500: Remove deprecated IRQF_DISABLED
clocksource: tegra: Remove deprecated IRQF_DISABLED
clocksource: misc drivers: Remove deprecated IRQF_DISABLED
clocksource: sh_mtu2: Remove unnecessary platform_set_drvdata()
clocksource: sh_tmu: Remove unnecessary platform_set_drvdata()
clocksource: armada-370-xp: Enable timer divider only when needed
clocksource: clksrc-of: Warn if no clock sources are found
clocksource: orion: Switch to sched_clock_register()
... -
Pull scheduler changes from Ingo Molnar:
- Add the initial implementation of SCHED_DEADLINE support: a real-time
scheduling policy where tasks that meet their deadlines and
periodically execute their instances in less than their runtime quota
see real-time scheduling and won't miss any of their deadlines.
Tasks that go over their quota get delayed (Available to privileged
users for now)- Clean up and fix preempt_enable_no_resched() abuse all around the
tree- Do sched_clock() performance optimizations on x86 and elsewhere
- Fix and improve auto-NUMA balancing
- Fix and clean up the idle loop
- Apply various cleanups and fixes
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
sched: Fix __sched_setscheduler() nice test
sched: Move SCHED_RESET_ON_FORK into attr::sched_flags
sched: Fix up attr::sched_priority warning
sched: Fix up scheduler syscall LTP fails
sched: Preserve the nice level over sched_setscheduler() and sched_setparam() calls
sched/core: Fix htmldocs warnings
sched/deadline: No need to check p if dl_se is valid
sched/deadline: Remove unused variables
sched/deadline: Fix sparse static warnings
m68k: Fix build warning in mac_via.h
sched, thermal: Clean up preempt_enable_no_resched() abuse
sched, net: Fixup busy_loop_us_clock()
sched, net: Clean up preempt_enable_no_resched() abuse
sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding
sched/preempt, locking: Rework local_bh_{dis,en}able()
sched/clock, x86: Avoid a runtime condition in native_sched_clock()
sched/clock: Fix up clear_sched_clock_stable()
sched/clock, x86: Use a static_key for sched_clock_stable
sched/clock: Remove local_irq_disable() from the clocks
sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs
...
16 Jan, 2014
1 commit
-
This makes the code more symetric against the existing tick functions
called on irq exit: tick_irq_exit() and tick_nohz_irq_exit().These function are also symetric as they mirror each other's action:
we start to account idle time on irq exit and we stop this accounting
on irq entry. Also the tick is stopped on irq exit and timekeeping
catches up with the tickless time elapsed until we reach irq entry.This rename was suggested by Peter Zijlstra a long while ago but it
got forgotten in the mass.Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Alex Shi
Cc: Steven Rostedt
Cc: Paul E. McKenney
Cc: John Stultz
Cc: Kevin Hilman
Link: http://lkml.kernel.org/r/1387320692-28460-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Frederic Weisbecker
14 Jan, 2014
1 commit
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Currently local_bh_disable() is out-of-line for no apparent reason.
So inline it to save a few cycles on call/return nonsense, the
function body is a single add on x86 (a few loads and store extra on
load/store archs).Also expose two new local_bh functions:
__local_bh_{dis,en}able_ip(unsigned long ip, unsigned int cnt);
Which implement the actual local_bh_{dis,en}able() behaviour.
The next patch uses the exposed @cnt argument to optimize bh lock
functions.With build fixes from Jacob Pan.
Cc: rjw@rjwysocki.net
Cc: rui.zhang@intel.com
Cc: jacob.jun.pan@linux.intel.com
Cc: Mike Galbraith
Cc: hpa@zytor.com
Cc: Arjan van de Ven
Cc: lenb@kernel.org
Reviewed-by: Thomas Gleixner
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar
13 Jan, 2014
1 commit
-
Currently all _bh_ lock functions do two preempt_count operations:
local_bh_disable();
preempt_disable();and for the unlock:
preempt_enable_no_resched();
local_bh_enable();Since its a waste of perfectly good cycles to modify the same variable
twice when you can do it in one go; use the new
__local_bh_{dis,en}able_ip() functions that allow us to provide a
preempt_count value to add/sub.So define SOFTIRQ_LOCK_OFFSET as the offset a _bh_ lock needs to
add/sub to be done in one go.As a bonus it gets rid of the preempt_enable_no_resched() usage.
This reduces a 1000 loops of:
spin_lock_bh(&bh_lock);
spin_unlock_bh(&bh_lock);from 53596 cycles to 51995 cycles. I didn't do enough measurements to
say for absolute sure that the result is significant but the the few
runs I did for each suggest it is so.Reviewed-by: Thomas Gleixner
Signed-off-by: Peter Zijlstra
Cc: jacob.jun.pan@linux.intel.com
Cc: Mike Galbraith
Cc: hpa@zytor.com
Cc: Arjan van de Ven
Cc: lenb@kernel.org
Cc: rjw@rjwysocki.net
Cc: rui.zhang@intel.com
Cc: Linus Torvalds
Cc: Andrew Morton
Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar
03 Dec, 2013
1 commit
-
A few functions use remote per CPU access APIs when they
deal with local values.Just do the right conversion to improve performance, code
readability and debug checks.While at it, lets extend some of these function names with *_this_cpu()
suffix in order to display their purpose more clearly.Signed-off-by: Frederic Weisbecker
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Oleg Nesterov
Cc: Steven Rostedt
27 Nov, 2013
2 commits
-
Instead of saving the hardirq state on a per CPU variable, which require
an explicit call before the softirq handling and some complication,
just save and restore the hardirq tracing state through functions
return values and parameters.It simplifies a bit the black magic that works around the fact that
softirqs can be called from hardirqs while hardirqs can nest on softirqs
but those two cases have very different semantics and only the latter
case assume both states.Signed-off-by: Frederic Weisbecker
Signed-off-by: Peter Zijlstra
Cc: Sebastian Andrzej Siewior
Cc: Linus Torvalds
Cc: Andrew Morton
Cc: Paul E. McKenney
Link: http://lkml.kernel.org/r/1384906054-30676-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
Prepare for dependent patch.
Signed-off-by: Ingo Molnar
20 Nov, 2013
1 commit
-
There was a reported deadlock on -rt which lockdep didn't report.
It turns out that in irq_exit() we tell lockdep that the hardirq
context ends and then do all kinds of locking afterwards.To fix it, move trace_hardirq_exit() to the very end of irq_exit(), this
ensures all locking in tick_irq_exit() and rcu_irq_exit() are properly
recorded as happening from hardirq context.This however leads to the 'fun' little problem of running softirqs
while in hardirq context. To cure this make the softirq code a little
more complex (in the CONFIG_TRACE_IRQFLAGS case).Due to stack swizzling arch dependent trickery we cannot pass an
argument to __do_softirq() to tell it if it was done from hardirq
context or not; so use a side-band argument.When we do __do_softirq() from hardirq context, 'atomically' flip to
softirq context and back, so that no locking goes without being in
either hard- or soft-irq context.I didn't find any new problems in mainline using this patch, but it
did show the -rt problem.Reported-by: Sebastian Andrzej Siewior
Cc: Frederic Weisbecker
Cc: Linus Torvalds
Cc: Andrew Morton
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/n/tip-dgwc5cdksbn0jk09vbmcc9sa@git.kernel.org
Signed-off-by: Ingo Molnar
15 Nov, 2013
1 commit
-
This commit was incomplete in that code to remove items from the per-cpu
lists was missing and never acquired a user in the 5 years it has been in
the tree. We're going to implement what it seems to try to archive in a
simpler way, and this code is in the way of doing so.Signed-off-by: Christoph Hellwig
Cc: Jan Kara
Cc: Jens Axboe
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Nov, 2013
1 commit
-
Pull scheduler changes from Ingo Molnar:
"The main changes in this cycle are:- (much) improved CONFIG_NUMA_BALANCING support from Mel Gorman, Rik
van Riel, Peter Zijlstra et al. Yay!- optimize preemption counter handling: merge the NEED_RESCHED flag
into the preempt_count variable, by Peter Zijlstra.- wait.h fixes and code reorganization from Peter Zijlstra
- cfs_bandwidth fixes from Ben Segall
- SMP load-balancer cleanups from Peter Zijstra
- idle balancer improvements from Jason Low
- other fixes and cleanups"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED
stop_machine: Fix race between stop_two_cpus() and stop_cpus()
sched: Remove unnecessary iteration over sched domains to update nr_busy_cpus
sched: Fix asymmetric scheduling for POWER7
sched: Move completion code from core.c to completion.c
sched: Move wait code from core.c to wait.c
sched: Move wait.c into kernel/sched/
sched/wait: Fix __wait_event_interruptible_lock_irq_timeout()
sched: Avoid throttle_cfs_rq() racing with period_timer stopping
sched: Guarantee new group-entities always have weight
sched: Fix hrtimer_cancel()/rq->lock deadlock
sched: Fix cfs_bandwidth misuse of hrtimer_expires_remaining
sched: Fix race on toggling cfs_bandwidth_used
sched: Remove extra put_online_cpus() inside sched_setaffinity()
sched/rt: Fix task_tick_rt() comment
sched/wait: Fix build breakage
sched/wait: Introduce prepare_to_wait_event()
sched/wait: Add ___wait_cond_timeout() to wait_event*_timeout() too
sched: Remove get_online_cpus() usage
sched: Fix race in migrate_swap_stop()
...
09 Oct, 2013
1 commit
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Merge Linux v3.12-rc4 to fix a conflict and also to refresh the tree
before applying more scheduler patches.Conflicts:
arch/avr32/include/asm/KbuildSigned-off-by: Ingo Molnar
01 Oct, 2013
6 commits
-
If irq_exit() is called on the arch's specified irq stack,
it should be safe to run softirqs inline under that same
irq stack as it is near empty by the time we call irq_exit().For example if we use the same stack for both hard and soft irqs here,
the worst case scenario is:
hardirq -> softirq -> hardirq. But then the softirq supersedes the
first hardirq as the stack user since irq_exit() is called in
a mostly empty stack. So the stack merge in this case looks acceptable.Stack overrun still have a chance to happen if hardirqs have more
opportunities to nest, but then it's another problem to solve.So lets adapt the irq exit's softirq stack on top of a new Kconfig symbol
that can be defined when irq_exit() runs on the irq stack. That way
we can spare some stack switch on irq processing and all the cache
issues that come along.Acked-by: Linus Torvalds
Signed-off-by: Frederic Weisbecker
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Paul Mackerras
Cc: James Hogan
Cc: James E.J. Bottomley
Cc: Helge Deller
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Cc: David S. Miller
Cc: Andrew Morton -
For clarity, comment the various stack choices for softirqs
processing, whether we execute them from ksoftirqd or
local_irq_enable() calls.Their use on irq_exit() is already commented.
Acked-by: Linus Torvalds
Signed-off-by: Frederic Weisbecker
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Paul Mackerras
Cc: James Hogan
Cc: James E.J. Bottomley
Cc: Helge Deller
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Cc: David S. Miller
Cc: Andrew Morton -
do_softirq() has a debug check that verifies that it is not nesting
on softirqs processing, nor miscounting the softirq part of the preempt
count.But making sure that softirqs processing don't nest is actually a more
generic concern that applies to any caller of __do_softirq().Do take it one step further and generalize that debug check to
any softirq processing.Acked-by: Linus Torvalds
Signed-off-by: Frederic Weisbecker
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Paul Mackerras
Cc: James Hogan
Cc: James E.J. Bottomley
Cc: Helge Deller
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Cc: David S. Miller
Cc: Andrew Morton -
Before processing softirqs on hardirq exit, we already
do the check for pending softirqs while hardirqs are
guaranteed to be disabled.So we can take a shortcut and safely jump to the arch
specific implementation directly.Acked-by: Linus Torvalds
Signed-off-by: Frederic Weisbecker
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Paul Mackerras
Cc: James Hogan
Cc: James E.J. Bottomley
Cc: Helge Deller
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Cc: David S. Miller
Cc: Andrew Morton -
All arch overriden implementations of do_softirq() share the following
common code: disable irqs (to avoid races with the pending check),
check if there are softirqs pending, then execute __do_softirq() on
a specific stack.Consolidate the common parts such that archs only worry about the
stack switch.Acked-by: Linus Torvalds
Signed-off-by: Frederic Weisbecker
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Paul Mackerras
Cc: James Hogan
Cc: James E.J. Bottomley
Cc: Helge Deller
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Cc: David S. Miller
Cc: Andrew Morton -
The commit facd8b80c67a3cf64a467c4a2ac5fb31f2e6745b
("irq: Sanitize invoke_softirq") converted irq exit
calls of do_softirq() to __do_softirq() on all architectures,
assuming it was only used there for its irq disablement
properties.But as a side effect, the softirqs processed in the end
of the hardirq are always called on the inline current
stack that is used by irq_exit() instead of the softirq
stack provided by the archs that override do_softirq().The result is mostly safe if the architecture runs irq_exit()
on a separate irq stack because then softirqs are processed
on that same stack that is near empty at this stage (assuming
hardirq aren't nesting).Otherwise irq_exit() runs in the task stack and so does the softirq
too. The interrupted call stack can be randomly deep already and
the softirq can dig through it even further. To add insult to the
injury, this softirq can be interrupted by a new hardirq, maximizing
the chances for a stack overrun as reported in powerpc for example:do_IRQ: stack overflow: 1920
CPU: 0 PID: 1602 Comm: qemu-system-ppc Not tainted 3.10.4-300.1.fc19.ppc64p7 #1
Call Trace:
[c0000000050a8740] .show_stack+0x130/0x200 (unreliable)
[c0000000050a8810] .dump_stack+0x28/0x3c
[c0000000050a8880] .do_IRQ+0x2b8/0x2c0
[c0000000050a8930] hardware_interrupt_common+0x154/0x180
--- Exception: 501 at .cp_start_xmit+0x3a4/0x820 [8139cp]
LR = .cp_start_xmit+0x390/0x820 [8139cp]
[c0000000050a8d40] .dev_hard_start_xmit+0x394/0x640
[c0000000050a8e00] .sch_direct_xmit+0x110/0x260
[c0000000050a8ea0] .dev_queue_xmit+0x260/0x630
[c0000000050a8f40] .br_dev_queue_push_xmit+0xc4/0x130 [bridge]
[c0000000050a8fc0] .br_dev_xmit+0x198/0x270 [bridge]
[c0000000050a9070] .dev_hard_start_xmit+0x394/0x640
[c0000000050a9130] .dev_queue_xmit+0x428/0x630
[c0000000050a91d0] .ip_finish_output+0x2a4/0x550
[c0000000050a9290] .ip_local_out+0x50/0x70
[c0000000050a9310] .ip_queue_xmit+0x148/0x420
[c0000000050a93b0] .tcp_transmit_skb+0x4e4/0xaf0
[c0000000050a94a0] .__tcp_ack_snd_check+0x7c/0xf0
[c0000000050a9520] .tcp_rcv_established+0x1e8/0x930
[c0000000050a95f0] .tcp_v4_do_rcv+0x21c/0x570
[c0000000050a96c0] .tcp_v4_rcv+0x734/0x930
[c0000000050a97a0] .ip_local_deliver_finish+0x184/0x360
[c0000000050a9840] .ip_rcv_finish+0x148/0x400
[c0000000050a98d0] .__netif_receive_skb_core+0x4f8/0xb00
[c0000000050a99d0] .netif_receive_skb+0x44/0x110
[c0000000050a9a70] .br_handle_frame_finish+0x2bc/0x3f0 [bridge]
[c0000000050a9b20] .br_nf_pre_routing_finish+0x2ac/0x420 [bridge]
[c0000000050a9bd0] .br_nf_pre_routing+0x4dc/0x7d0 [bridge]
[c0000000050a9c70] .nf_iterate+0x114/0x130
[c0000000050a9d30] .nf_hook_slow+0xb4/0x1e0
[c0000000050a9e00] .br_handle_frame+0x290/0x330 [bridge]
[c0000000050a9ea0] .__netif_receive_skb_core+0x34c/0xb00
[c0000000050a9fa0] .netif_receive_skb+0x44/0x110
[c0000000050aa040] .napi_gro_receive+0xe8/0x120
[c0000000050aa0c0] .cp_rx_poll+0x31c/0x590 [8139cp]
[c0000000050aa1d0] .net_rx_action+0x1dc/0x310
[c0000000050aa2b0] .__do_softirq+0x158/0x330
[c0000000050aa3b0] .irq_exit+0xc8/0x110
[c0000000050aa430] .do_IRQ+0xdc/0x2c0
[c0000000050aa4e0] hardware_interrupt_common+0x154/0x180
--- Exception: 501 at .bad_range+0x1c/0x110
LR = .get_page_from_freelist+0x908/0xbb0
[c0000000050aa7d0] .list_del+0x18/0x50 (unreliable)
[c0000000050aa850] .get_page_from_freelist+0x908/0xbb0
[c0000000050aa9e0] .__alloc_pages_nodemask+0x21c/0xae0
[c0000000050aaba0] .alloc_pages_vma+0xd0/0x210
[c0000000050aac60] .handle_pte_fault+0x814/0xb70
[c0000000050aad50] .__get_user_pages+0x1a4/0x640
[c0000000050aae60] .get_user_pages_fast+0xec/0x160
[c0000000050aaf10] .__gfn_to_pfn_memslot+0x3b0/0x430 [kvm]
[c0000000050aafd0] .kvmppc_gfn_to_pfn+0x64/0x130 [kvm]
[c0000000050ab070] .kvmppc_mmu_map_page+0x94/0x530 [kvm]
[c0000000050ab190] .kvmppc_handle_pagefault+0x174/0x610 [kvm]
[c0000000050ab270] .kvmppc_handle_exit_pr+0x464/0x9b0 [kvm]
[c0000000050ab320] kvm_start_lightweight+0x1ec/0x1fc [kvm]
[c0000000050ab4f0] .kvmppc_vcpu_run_pr+0x168/0x3b0 [kvm]
[c0000000050ab9c0] .kvmppc_vcpu_run+0xc8/0xf0 [kvm]
[c0000000050aba50] .kvm_arch_vcpu_ioctl_run+0x5c/0x1a0 [kvm]
[c0000000050abae0] .kvm_vcpu_ioctl+0x478/0x730 [kvm]
[c0000000050abc90] .do_vfs_ioctl+0x4ec/0x7c0
[c0000000050abd80] .SyS_ioctl+0xd4/0xf0
[c0000000050abe30] syscall_exit+0x0/0x98Since this is a regression, this patch proposes a minimalistic
and low-risk solution by blindly forcing the hardirq exit processing of
softirqs on the softirq stack. This way we should reduce significantly
the opportunities for task stack overflow dug by softirqs.Longer term solutions may involve extending the hardirq stack coverage to
irq_exit(), etc...Reported-by: Benjamin Herrenschmidt
Acked-by: Linus Torvalds
Signed-off-by: Frederic Weisbecker
Cc: #3.9..
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Paul Mackerras
Cc: James Hogan
Cc: James E.J. Bottomley
Cc: Helge Deller
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Cc: David S. Miller
Cc: Andrew Morton
25 Sep, 2013
2 commits
-
Rewrite the preempt_count macros in order to extract the 3 basic
preempt_count value modifiers:__preempt_count_add()
__preempt_count_sub()and the new:
__preempt_count_dec_and_test()
And since we're at it anyway, replace the unconventional
$op_preempt_count names with the more conventional preempt_count_$op.Since these basic operators are equivalent to the previous _notrace()
variants, do away with the _notrace() versions.Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/n/tip-ewbpdbupy9xpsjhg960zwbv8@git.kernel.org
Signed-off-by: Ingo Molnar -
Replace the single preempt_count() 'function' that's an lvalue with
two proper functions:preempt_count() - returns the preempt_count value as rvalue
preempt_count_set() - Allows setting the preempt-count valueAlso provide preempt_count_ptr() as a convenience wrapper to implement
all modifying operations.Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/n/tip-orxrbycjozopqfhb4dxdkdvb@git.kernel.org
[ Fixed build failure. ]
Signed-off-by: Ingo Molnar
13 Sep, 2013
1 commit
-
After the last architecture switched to generic hard irqs the config
options HAVE_GENERIC_HARDIRQS & GENERIC_HARDIRQS and the related code
for !CONFIG_GENERIC_HARDIRQS can be removed.Signed-off-by: Martin Schwidefsky
15 Jul, 2013
1 commit
-
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.This removes all the uses of the __cpuinit macros from C files in
the core kernel directories (kernel, init, lib, mm, and include)
that don't really have a specific maintainer.[1] https://lkml.org/lkml/2013/5/20/589
Signed-off-by: Paul Gortmaker
03 Jul, 2013
1 commit
-
Pull core irq changes from Ingo Molnar:
"The main changes:- generic-irqchip driver additions, cleanups and fixes
- 3 new irqchip drivers: ARMv7-M NVIC, TB10x and Marvell Orion SoCs
- irq_get_trigger_type() simplification and cross-arch cleanup
- various cleanups, simplifications
- documentation updates"
* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
softirq: Use _RET_IP_
genirq: Add the generic chip to the genirq docbook
genirq: generic-chip: Export some irq_gc_ functions
genirq: Fix can_request_irq() for IRQs without an action
irqchip: exynos-combiner: Staticize combiner_init
irqchip: Add support for ARMv7-M NVIC
irqchip: Add TB10x interrupt controller driver
irqdomain: Use irq_get_trigger_type() to get IRQ flags
MIPS: octeon: Use irq_get_trigger_type() to get IRQ flags
arm: orion: Use irq_get_trigger_type() to get IRQ flags
mfd: stmpe: use irq_get_trigger_type() to get IRQ flags
mfd: twl4030-irq: Use irq_get_trigger_type() to get IRQ flags
gpio: mvebu: Use irq_get_trigger_type() to get IRQ flags
genirq: Add irq_get_trigger_type() to get IRQ flags
genirq: Irqchip: document gcflags arg of irq_alloc_domain_generic_chips
genirq: Set irq thread to RT priority on creation
irqchip: Add support for Marvell Orion SoCs
genirq: Add kerneldoc for irq_disable.
genirq: irqchip: Add mask to block out invalid irqs
genirq: Generic chip: Add linear irq domain support
...
28 Jun, 2013
1 commit
-
Use the already defined macro to pass the function return address.
Signed-off-by: Davidlohr Bueso
Cc: Frederic Weisbecker
Link: http://lkml.kernel.org/r/1367347569.1784.3.camel@buesod1.americas.hpqcorp.net
Signed-off-by: Thomas Gleixner
11 Jun, 2013
1 commit
-
The stop machine logic can lock up if all but one of the migration
threads make it through the disable-irq step and the one remaining
thread gets stuck in __do_softirq. The reason __do_softirq can hang is
that it has a bail-out based on jiffies timeout, but in the lockup case,
jiffies itself is not incremented.To work around this, re-add the max_restart counter in __do_irq and stop
processing irqs after 10 restarts.Thanks to Tejun Heo and Rusty Russell and others for helping me track
this down.This was introduced in 3.9 by commit c10d73671ad3 ("softirq: reduce
latencies").It may be worth looking into ath9k to see if it has issues with its irq
handler at a later date.The hang stack traces look something like this:
------------[ cut here ]------------
WARNING: at kernel/watchdog.c:245 watchdog_overflow_callback+0x9c/0xa7()
Watchdog detected hard LOCKUP on cpu 2
Modules linked in: ath9k ath9k_common ath9k_hw ath mac80211 cfg80211 nfsv4 auth_rpcgss nfs fscache nf_nat_ipv4 nf_nat veth 8021q garp stp mrp llc pktgen lockd sunrpc]
Pid: 23, comm: migration/2 Tainted: G C 3.9.4+ #11
Call Trace:
warn_slowpath_common+0x85/0x9f
warn_slowpath_fmt+0x46/0x48
watchdog_overflow_callback+0x9c/0xa7
__perf_event_overflow+0x137/0x1cb
perf_event_overflow+0x14/0x16
intel_pmu_handle_irq+0x2dc/0x359
perf_event_nmi_handler+0x19/0x1b
nmi_handle+0x7f/0xc2
do_nmi+0xbc/0x304
end_repeat_nmi+0x1e/0x2e
<>
cpu_stopper_thread+0xae/0x162
smpboot_thread_fn+0x258/0x260
kthread+0xc7/0xcf
ret_from_fork+0x7c/0xb0
---[ end trace 4947dfa9b0a4cec3 ]---
BUG: soft lockup - CPU#1 stuck for 22s! [migration/1:17]
Modules linked in: ath9k ath9k_common ath9k_hw ath mac80211 cfg80211 nfsv4 auth_rpcgss nfs fscache nf_nat_ipv4 nf_nat veth 8021q garp stp mrp llc pktgen lockd sunrpc]
irq event stamp: 835637905
hardirqs last enabled at (835637904): __do_softirq+0x9f/0x257
hardirqs last disabled at (835637905): apic_timer_interrupt+0x6d/0x80
softirqs last enabled at (5654720): __do_softirq+0x1ff/0x257
softirqs last disabled at (5654725): irq_exit+0x5f/0xbb
CPU 1
Pid: 17, comm: migration/1 Tainted: G WC 3.9.4+ #11 To be filled by O.E.M. To be filled by O.E.M./To be filled by O.E.M.
RIP: tasklet_hi_action+0xf0/0xf0
Process migration/1
Call Trace:
__do_softirq+0x117/0x257
irq_exit+0x5f/0xbb
smp_apic_timer_interrupt+0x8a/0x98
apic_timer_interrupt+0x72/0x80
printk+0x4d/0x4f
stop_machine_cpu_stop+0x22c/0x274
cpu_stopper_thread+0xae/0x162
smpboot_thread_fn+0x258/0x260
kthread+0xc7/0xcf
ret_from_fork+0x7c/0xb0Signed-off-by: Ben Greear
Acked-by: Tejun Heo
Acked-by: Pekka Riikonen
Cc: Eric Dumazet
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
06 May, 2013
1 commit
-
Pull 'full dynticks' support from Ingo Molnar:
"This tree from Frederic Weisbecker adds a new, (exciting! :-) core
kernel feature to the timer and scheduler subsystems: 'full dynticks',
or CONFIG_NO_HZ_FULL=y.This feature extends the nohz variable-size timer tick feature from
idle to busy CPUs (running at most one task) as well, potentially
reducing the number of timer interrupts significantly.This feature got motivated by real-time folks and the -rt tree, but
the general utility and motivation of full-dynticks runs wider than
that:- HPC workloads get faster: CPUs running a single task should be able
to utilize a maximum amount of CPU power. A periodic timer tick at
HZ=1000 can cause a constant overhead of up to 1.0%. This feature
removes that overhead - and speeds up the system by 0.5%-1.0% on
typical distro configs even on modern systems.- Real-time workload latency reduction: CPUs running critical tasks
should experience as little jitter as possible. The last remaining
source of kernel-related jitter was the periodic timer tick.- A single task executing on a CPU is a pretty common situation,
especially with an increasing number of cores/CPUs, so this feature
helps desktop and mobile workloads as well.The cost of the feature is mainly related to increased timer
reprogramming overhead when a CPU switches its tick period, and thus
slightly longer to-idle and from-idle latency.Configuration-wise a third mode of operation is added to the existing
two NOHZ kconfig modes:- CONFIG_HZ_PERIODIC: [formerly !CONFIG_NO_HZ], now explicitly named
as a config option. This is the traditional Linux periodic tick
design: there's a HZ tick going on all the time, regardless of
whether a CPU is idle or not.- CONFIG_NO_HZ_IDLE: [formerly CONFIG_NO_HZ=y], this turns off the
periodic tick when a CPU enters idle mode.- CONFIG_NO_HZ_FULL: this new mode, in addition to turning off the
tick when a CPU is idle, also slows the tick down to 1 Hz (one
timer interrupt per second) when only a single task is running on a
CPU.The .config behavior is compatible: existing !CONFIG_NO_HZ and
CONFIG_NO_HZ=y settings get translated to the new values, without the
user having to configure anything. CONFIG_NO_HZ_FULL is turned off by
default.This feature is based on a lot of infrastructure work that has been
steadily going upstream in the last 2-3 cycles: related RCU support
and non-periodic cputime support in particular is upstream already.This tree adds the final pieces and activates the feature. The pull
request is marked RFC because:- it's marked 64-bit only at the moment - the 32-bit support patch is
small but did not get ready in time.- it has a number of fresh commits that came in after the merge
window. The overwhelming majority of commits are from before the
merge window, but still some aspects of the tree are fresh and so I
marked it RFC.- it's a pretty wide-reaching feature with lots of effects - and
while the components have been in testing for some time, the full
combination is still not very widely used. That it's default-off
should reduce its regression abilities and obviously there are no
known regressions with CONFIG_NO_HZ_FULL=y enabled either.- the feature is not completely idempotent: there is no 100%
equivalent replacement for a periodic scheduler/timer tick. In
particular there's ongoing work to map out and reduce its effects
on scheduler load-balancing and statistics. This should not impact
correctness though, there are no known regressions related to this
feature at this point.- it's a pretty ambitious feature that with time will likely be
enabled by most Linux distros, and we'd like you to make input on
its design/implementation, if you dislike some aspect we missed.
Without flaming us to crisp! :-)Future plans:
- there's ongoing work to reduce 1Hz to 0Hz, to essentially shut off
the periodic tick altogether when there's a single busy task on a
CPU. We'd first like 1 Hz to be exposed more widely before we go
for the 0 Hz target though.- once we reach 0 Hz we can remove the periodic tick assumption from
nr_running>=2 as well, by essentially interrupting busy tasks only
as frequently as the sched_latency constraints require us to do -
once every 4-40 msecs, depending on nr_running.I am personally leaning towards biting the bullet and doing this in
v3.10, like the -rt tree this effort has been going on for too long -
but the final word is up to you as usual.More technical details can be found in Documentation/timers/NO_HZ.txt"
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
sched: Keep at least 1 tick per second for active dynticks tasks
rcu: Fix full dynticks' dependency on wide RCU nocb mode
nohz: Protect smp_processor_id() in tick_nohz_task_switch()
nohz_full: Add documentation.
cputime_nsecs: use math64.h for nsec resolution conversion helpers
nohz: Select VIRT_CPU_ACCOUNTING_GEN from full dynticks config
nohz: Reduce overhead under high-freq idling patterns
nohz: Remove full dynticks' superfluous dependency on RCU tree
nohz: Fix unavailable tick_stop tracepoint in dynticks idle
nohz: Add basic tracing
nohz: Select wide RCU nocb for full dynticks
nohz: Disable the tick when irq resume in full dynticks CPU
nohz: Re-evaluate the tick for the new task after a context switch
nohz: Prepare to stop the tick on irq exit
nohz: Implement full dynticks kick
nohz: Re-evaluate the tick from the scheduler IPI
sched: New helper to prevent from stopping the tick in full dynticks
sched: Kick full dynticks CPU that have more than one task enqueued.
perf: New helper to prevent full dynticks CPUs from stopping tick
perf: Kick full dynticks CPU if events rotation is needed
...
02 May, 2013
1 commit
-
The full dynticks tree needs the latest RCU and sched
upstream updates in order to fix some dependencies.Merge a common upstream merge point that has these
updates.Conflicts:
include/linux/perf_event.h
kernel/rcutree.h
kernel/rcutree_plugin.hSigned-off-by: Frederic Weisbecker
01 May, 2013
1 commit
-
The 'priv' field is redundant; we can pass data via 'info'.
Signed-off-by: liguang
Cc: Peter Zijlstra
Cc: Oleg Nesterov
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Apr, 2013
1 commit
-
Eventually try to disable tick on irq exit, now that the
fundamental infrastructure is in place.Signed-off-by: Frederic Weisbecker
Cc: Chris Metcalf
Cc: Christoph Lameter
Cc: Geoff Levand
Cc: Gilad Ben Yossef
Cc: Hakan Akkan
Cc: Ingo Molnar
Cc: Kevin Hilman
Cc: Li Zhong
Cc: Oleg Nesterov
Cc: Paul E. McKenney
Cc: Paul Gortmaker
Cc: Peter Zijlstra
Cc: Steven Rostedt
Cc: Thomas Gleixner
03 Apr, 2013
1 commit
-
We are planning to convert the dynticks Kconfig options layout
into a choice menu. The user must be able to easily pick
any of the following implementations: constant periodic tick,
idle dynticks, full dynticks.As this implies a mutual exclusion, the two dynticks implementions
need to converge on the selection of a common Kconfig option in order
to ease the sharing of a common infrastructure.It would thus seem pretty natural to reuse CONFIG_NO_HZ to
that end. It already implements all the idle dynticks code
and the full dynticks depends on all that code for now.
So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and
CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ.On the other hand we want to stay backward compatible: if
CONFIG_NO_HZ is set in an older config file, we want to
enable CONFIG_NO_HZ_IDLE by default.But we can't afford both at the same time or we run into
a circular dependency:1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select
CONFIG_NO_HZ
2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLEWe might be able to support that from Kconfig/Kbuild but it
may not be wise to introduce such a confusing behaviour.So to solve this, create a new CONFIG_NO_HZ_COMMON option
which gathers the common code between idle and full dynticks
(that common code for now is simply the idle dynticks code)
and select it from their referring Kconfig.Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ
to it for backward compatibility.Signed-off-by: Frederic Weisbecker
Cc: Andrew Morton
Cc: Chris Metcalf
Cc: Christoph Lameter
Cc: Geoff Levand
Cc: Gilad Ben Yossef
Cc: Hakan Akkan
Cc: Ingo Molnar
Cc: Kevin Hilman
Cc: Li Zhong
Cc: Namhyung Kim
Cc: Paul E. McKenney
Cc: Paul Gortmaker
Cc: Peter Zijlstra
Cc: Steven Rostedt
Cc: Thomas Gleixner
06 Mar, 2013
1 commit
-
Pull irq fixes and cleanups from Thomas Gleixner:
"Commit e5ab012c3271 ("nohz: Make tick_nohz_irq_exit() irq safe") is
the first commit in the series and the minimal necessary bugfix, which
needs to go back into stable.The remanining commits enforce irq disabling in irq_exit(), sanitize
the hardirq/softirq preempt count transition and remove a bunch of no
longer necessary conditionals."I personally love getting rid of the very subtle and confusing
IRQ_EXIT_OFFSET thing. Even apart from the whole "more lines removed
than added" thing.* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irq: Don't re-enable interrupts at the end of irq_exit
irq: Remove IRQ_EXIT_OFFSET workaround
Revert "nohz: Make tick_nohz_irq_exit() irq safe"
irq: Sanitize invoke_softirq
irq: Ensure irq_exit() code runs with interrupts disabled
nohz: Make tick_nohz_irq_exit() irq safe
01 Mar, 2013
1 commit
-
Commit 74eed0163d0def3fce27228d9ccf3d36e207b286
"irq: Ensure irq_exit() code runs with interrupts disabled"
restore interrupts flags in the end of irq_exit() for archs
that don't define __ARCH_IRQ_EXIT_IRQS_DISABLED.However always returning from irq_exit() with interrupts
disabled should not be a problem for these archs. Prior to
this commit this was already happening anytime we processed
pending softirqs anyway.Suggested-by: Linus Torvalds
Signed-off-by: Frederic Weisbecker
Cc: Linus Torvalds
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Paul E. McKenney
22 Feb, 2013
2 commits
-
The IRQ_EXIT_OFFSET trick was used to make sure the irq
doesn't get preempted after we substract the HARDIRQ_OFFSET
until we are entirely done with any code in irq_exit().This workaround was necessary because some archs may call
irq_exit() with irqs enabled and there is still some code
in the end of this function that is not covered by the
HARDIRQ_OFFSET but want to stay non-preemptible.Now that irq are always disabled in irq_exit(), the whole code
is guaranteed not to be preempted. We can thus remove this hack.Signed-off-by: Frederic Weisbecker
Cc: Linus Torvalds
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Paul E. McKenney -
With the irq protection in irq_exit, we can remove the #ifdeffery and
the bh_disable/enable dance in invoke_softirq()Signed-off-by: Thomas Gleixner
Cc: Frederic Weisbecker
Cc: Peter Zijlstra
Cc: Ingo Molnar
Cc: Paul E. McKenney
Cc: Linus Torvalds
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1302202155320.22263@ionos