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Filters need to be translated to real BPF code for userland, like SO_GETFILTER.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas into next/dt
From Simon Horman:
Renesas ARM-based SoC DT updates for v3.11
* Armadillo800eva reference DT - bring up armadillo800eva baord
using DT as much as possible
* Remove unused GIC dtsi entries for r8a7790 and r8a73a4
* Add AS3711 and CPUFreq DT bindings for kzm9g-reference
* Add irqpin DT support for marzen-reference
* tag 'renesas-dt-for-v3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas:
ARM: shmobile: marzen-reference: add irqpin support in DT
ARM: shmobile: kzm9g-reference: add AS3711 and CPUFreq DT bindings
ARM: shmobile: armadillo800eva: Reference DT implementation
ARM: shmobile: Remove unused r8a7790 GIC CPU interface DT bits
ARM: shmobile: Remove unused r8a73a4 GIC CPU interface DT bits
ARM: shmobile: r8a7740: Prepare for reference DT setup
ARM: shmobile: r8a7740: Add OF support to initialze the GIC
Signed-off-by: Olof Johansson <olof@lixom.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas into next/boards
From Simon Horman:
Renesas ARM based SoC defconfig updates for v3.11
kzm9g: Enable AS3711 PMIC
bockw: Enable, USB, PM_RUNTIME, I2C and SDHI
armadillo800eva: Correct SERIAL_SH_SCI_NR_UARTS
* tag 'renesas-defconfig-for-v3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas:
ARM: shmobile: kzm9g: enable AS3711 PMIC in defconfig
ARM: shmobile: bockw: enable USB in defconfig
ARM: shmobile: bockw: enable CONFIG_PM_RUNTIME in defconfig
ARM: shmobile: bockw: enable I2C in defconfig
ARM: shmobile: bockw: enable SDHI on defconfig
ARM: shmobile: armadillo800eva: Fix maximum number of SCIF
Signed-off-by: Olof Johansson <olof@lixom.net>
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into next/soc
From Jason Cooper:
mvebu pcie driver (kirkwood) for v3.11 (round 2)
- kirkwood
- migrate Netgear ReadyNAS Duo v2 to pcie DT init
* tag 'pcie_kw-3.11-2' of git://git.infradead.org/users/jcooper/linux:
arm: kirkwood: NETGEAR ReadyNAS Duo v2 init PCIe via DT
Signed-off-by: Olof Johansson <olof@lixom.net>
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next/dt
From Jason Cooper:
mvebu dt changes for v3.11 (round 4)
- kirkwood
- reshuffle nodes from kirkwood.dtsi to -6281.dtsi, etc
- add i2c-gpio for km_kirkwood
- add cpu node so pending cpufreq driver will init
* tag 'dt-3.11-4' of git://git.infradead.org/users/jcooper/linux:
ARM: Kirkwood add cpus definition needed by cpufreq driver to dtsi
ARM: kirkwood: add i2c-gpio controller for km_kirkwood
ARM: kirkwood: refactor dtsi to largest common nodes
Signed-off-by: Olof Johansson <olof@lixom.net>
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Several drivers don't build on s390 with CONFIG_PCI disabled as
they require MMIO functions.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org # 3.9
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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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:
<NMI> 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
<<EOE>>
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:
<IRQ>
__do_softirq+0x117/0x257
irq_exit+0x5f/0xbb
smp_apic_timer_interrupt+0x8a/0x98
apic_timer_interrupt+0x72/0x80
<EOI>
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/0xb0
Signed-off-by: Ben Greear <greearb@candelatech.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Pekka Riikonen <priikone@iki.fi>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs
Pull net/9p bug fix from Eric Van Hensbergen:
"zero copy error fix"
* tag '9p-3.10-bug-fix-1' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs:
net/9p: Handle error in zero copy request correctly for 9p2000.u
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In (bc6bcb5 netfilter: xt_TCPOPTSTRIP: fix possible mangling beyond
packet boundary), the use of tcp_hdr was introduced. However, we
cannot assume that skb->transport_header is set for non-local packets.
Cc: Florian Westphal <fw@strlen.de>
Reported-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Patrik writes:
Two fixes for memory leaks split into Cedarview and Poulsbo versions,
and a fix for properly setting the pipe base when using fbdev. It's on
my todo-list to start unifying the chips since they are very similar,
but until then I'd like to split them up in case there are side-effects
on Cedarview that I cannot currently test.
airled: Verified pull from github matches what I expected.
* 'gma500-fixes' of git://github.com/patjak/drm-gma500:
drm/gma500/cdv: Fix cursor gem obj referencing on cdv
drm/gma500/psb: Fix cursor gem obj referencing on psb
drm/gma500/cdv: Unpin framebuffer on crtc disable
drm/gma500/psb: Unpin framebuffer on crtc disable
drm/gma500: Add fb gtt offset to fb base
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'mout_mpll' is added the list of parent clocks for 'mout_cpu'.
'mout_mpll' is an alias to the clock 'sclk_mpll'. Hence 'sclk_mpll'
should be added to the list of parent clocks.
This results in an error when cpufreq driver for EXYNOS5250 tries to
set 'mout_mpll' as a parent for 'mout_cpu'.
clk_set_parent: clk sclk_mpll can not be parent of clk mout_cpu
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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cpufreq driver for EXYNOS5250 is not a platform driver, hence we cannot
currently pass the clock names through a device tree node. Instead, we
need to make them available through a global alias.
cpufreq driver for EXYNOS5250 requires four clocks - 'armclk',
'mout_cpu', 'mout_mpll' and 'mout_apll'.
'armclk' has already been defined with an alias, 'mout_cpu', 'mout_mpll'
and 'mout_apll' are now defined with an alias.
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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The usb_serial_port structure had the number field, which was the minor
number for the port, which almost no one really cared about. They
really wanted the number of the port within the device, which you had to
subtract from the minor of the parent usb_serial_device structure. To
clean this up, provide the real minor number of the port, and the number
of the port within the serial device separately, as these numbers might
not be related in the future.
Bonus is that this cleans up a lot of logic in the drivers, and saves
lines overall.
Tested-by: Tobias Winter <tobias@linuxdingsda.de>
Reviewed-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--
drivers/staging/serqt_usb2/serqt_usb2.c | 21 +++--------
drivers/usb/serial/ark3116.c | 2 -
drivers/usb/serial/bus.c | 6 +--
drivers/usb/serial/console.c | 2 -
drivers/usb/serial/cp210x.c | 2 -
drivers/usb/serial/cypress_m8.c | 4 +-
drivers/usb/serial/digi_acceleport.c | 6 ---
drivers/usb/serial/f81232.c | 5 +-
drivers/usb/serial/garmin_gps.c | 6 +--
drivers/usb/serial/io_edgeport.c | 58 ++++++++++++--------------------
drivers/usb/serial/io_ti.c | 21 ++++-------
drivers/usb/serial/keyspan.c | 29 +++++++---------
drivers/usb/serial/metro-usb.c | 4 +-
drivers/usb/serial/mos7720.c | 37 +++++++++-----------
drivers/usb/serial/mos7840.c | 52 +++++++++-------------------
drivers/usb/serial/opticon.c | 2 -
drivers/usb/serial/pl2303.c | 2 -
drivers/usb/serial/quatech2.c | 7 +--
drivers/usb/serial/sierra.c | 2 -
drivers/usb/serial/ti_usb_3410_5052.c | 10 ++---
drivers/usb/serial/usb-serial.c | 7 ++-
drivers/usb/serial/usb_wwan.c | 2 -
drivers/usb/serial/whiteheat.c | 20 +++++------
include/linux/usb/serial.h | 6 ++-
24 files changed, 133 insertions(+), 180 deletions(-)
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Complier may generate codes that re-read the tun->numqueues during
tun_select_queue(). This may be a race if vlan->numqueues were changed in the
same time and can lead unexpected result (e.g. very huge value).
We need prevent the compiler from generating such codes by adding an
ACCESS_ONCE() to make sure tun->numqueues were only read once.
Bug were introduced by commit c8d68e6be1c3b242f1c598595830890b65cea64a
(tuntap: multiqueue support).
Reported-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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When we decide not use zero-copy, msg.control should be set to NULL otherwise
macvtap/tap may set zerocopy callbacks which may decrease the kref of ubufs
wrongly.
Bug were introduced by commit cedb9bdce099206290a2bdd02ce47a7b253b6a84
(vhost-net: skip head management if no outstanding).
This solves the following warnings:
WARNING: at include/linux/kref.h:47 handle_tx+0x477/0x4b0 [vhost_net]()
Modules linked in: vhost_net macvtap macvlan tun nfsd exportfs bridge stp llc openvswitch kvm_amd kvm bnx2 megaraid_sas [last unloaded: tun]
CPU: 5 PID: 8670 Comm: vhost-8668 Not tainted 3.10.0-rc2+ #1566
Hardware name: Dell Inc. PowerEdge R715/00XHKG, BIOS 1.5.2 04/19/2011
ffffffffa0198323 ffff88007c9ebd08 ffffffff81796b73 ffff88007c9ebd48
ffffffff8103d66b 000000007b773e20 ffff8800779f0000 ffff8800779f43f0
ffff8800779f8418 000000000000015c 0000000000000062 ffff88007c9ebd58
Call Trace:
[<ffffffff81796b73>] dump_stack+0x19/0x1e
[<ffffffff8103d66b>] warn_slowpath_common+0x6b/0xa0
[<ffffffff8103d6b5>] warn_slowpath_null+0x15/0x20
[<ffffffffa0197627>] handle_tx+0x477/0x4b0 [vhost_net]
[<ffffffffa0197690>] handle_tx_kick+0x10/0x20 [vhost_net]
[<ffffffffa019541e>] vhost_worker+0xfe/0x1a0 [vhost_net]
[<ffffffffa0195320>] ? vhost_attach_cgroups_work+0x30/0x30 [vhost_net]
[<ffffffffa0195320>] ? vhost_attach_cgroups_work+0x30/0x30 [vhost_net]
[<ffffffff81061f46>] kthread+0xc6/0xd0
[<ffffffff81061e80>] ? kthread_freezable_should_stop+0x70/0x70
[<ffffffff817a1aec>] ret_from_fork+0x7c/0xb0
[<ffffffff81061e80>] ? kthread_freezable_should_stop+0x70/0x70
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch reworks the UEFI anti-bricking code, including an effective
reversion of cc5a080c and 31ff2f20. It turns out that calling
QueryVariableInfo() from boot services results in some firmware
implementations jumping to physical addresses even after entering virtual
mode, so until we have 1:1 mappings for UEFI runtime space this isn't
going to work so well.
Reverting these gets us back to the situation where we'd refuse to create
variables on some systems because they classify deleted variables as "used"
until the firmware triggers a garbage collection run, which they won't do
until they reach a lower threshold. This results in it being impossible to
install a bootloader, which is unhelpful.
Feedback from Samsung indicates that the firmware doesn't need more than
5KB of storage space for its own purposes, so that seems like a reasonable
threshold. However, there's still no guarantee that a platform will attempt
garbage collection merely because it drops below this threshold. It seems
that this is often only triggered if an attempt to write generates a
genuine EFI_OUT_OF_RESOURCES error. We can force that by attempting to
create a variable larger than the remaining space. This should fail, but if
it somehow succeeds we can then immediately delete it.
I've tested this on the UEFI machines I have available, but I don't have
a Samsung and so can't verify that it avoids the bricking problem.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Lee, Chun-Y <jlee@suse.com> [ dummy variable cleanup ]
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
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'srcu.2013.06.10a' and 'tiny.2013.06.10a' into HEAD
cbnum.2013.06.10a: Apply simplifications stemming from the new callback
numbering.
doc.2013.06.10a: Documentation updates.
fixes.2013.06.10a: Miscellaneous fixes.
srcu.2013.06.10a: Updates to SRCU.
tiny.2013.06.10a: Eliminate TINY_PREEMPT_RCU.
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TINY_RCU's reset_cpu_stall_ticks() and check_cpu_stalls() functions
are defined unconditionally, and are empty functions if CONFIG_RCU_TRACE
is disabled (which in turns disables detection of RCU CPU stalls).
This commit saves a few lines of source code by defining these functions
only if CONFIG_RCU_TRACE=y.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Now that TINY_PREEMPT_RCU is no more, exit_rcu() is always an empty
function. But if TINY_RCU is going to have an empty function, it should
be in include/linux/rcutiny.h, where it does not bloat the kernel.
This commit therefore moves exit_rcu() out of kernel/rcupdate.c to
kernel/rcutree_plugin.h, and places a static inline empty function in
include/linux/rcutiny.h in order to shrink TINY_RCU a bit.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Because TINY_PREEMPT_RCU is no more, this commit removes its tracing
formats from the documentation.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit rearranges code in order to allow ifdefs to be consolidated
in kernel/rcutiny_plugin.h, simplifying the code.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_note_context_switch()
is now an empty function. This commit therefore eliminates it by inlining it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Now that CONFIG_TINY_PREEMPT_RCU is no more, this commit removes
the CONFIG_TINY_RCU ifdefs from include/linux/rcutiny.h in favor of
unconditionally compiling the CONFIG_TINY_RCU legs of those ifdefs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Moved removal of #else to "Remove TINY_PREEMPT_RCU" as
suggested by Josh Triplett. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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With the removal of CONFIG_TINY_PREEMPT_RCU, check_cpu_stall_preempt()
is now an empty function. This commit therefore eliminates it by
inlining it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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TINY_PREEMPT_RCU could use a kthread to handle RCU callback invocation,
which required an API to abstract kthread vs. softirq invocation.
Now that TINY_PREEMPT_RCU is no longer with us, this commit retires
this API in favor of direct use of the relevant softirq primitives.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_process_callbacks()
is now an empty function. This commit therefore eliminates it by
inlining it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_remove_callbacks()
is now an empty function. This commit therefore eliminates it by
inlining it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_check_callbacks()
is now an empty function. This commit therefore eliminates it by
inlining it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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With the removal of CONFIG_TINY_PREEMPT_RCU, show_tiny_preempt_stats()
is now an empty function. This commit therefore eliminates it by
inlining it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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TINY_PREEMPT_RCU adds significant code and complexity, but does not
offer commensurate benefits. People currently using TINY_PREEMPT_RCU
can get much better memory footprint with TINY_RCU, or, if they really
need preemptible RCU, they can use TREE_PREEMPT_RCU with a relatively
minor degradation in memory footprint. Please note that this move
has been widely publicized on LKML (https://lkml.org/lkml/2012/11/12/545)
and on LWN (http://lwn.net/Articles/541037/).
This commit therefore removes TINY_PREEMPT_RCU.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updated to eliminate #else in rcutiny.h as suggested by Josh ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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At the point of up_out label in kvmppc_hv_setup_htab_rma(),
srcu read lock is still held.
We have to release it before return.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: kvm@vger.kernel.org
Cc: kvm-ppc@vger.kernel.org
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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These interfaces never did get used, so this commit removes them,
their rcutorture tests, and documentation referencing them.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The Kconfig help text for the RCU_NOCB_CPU_NONE, RCU_NOCB_CPU_ZERO,
and RCU_NOCB_CPU_ALL Kconfig options was unclear, so this commit
adds a bit more detail.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Two ifdefs in kernel/rcupdate.c now have identical conditions with
nothing between them, so the commit merges them into a single ifdef.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Systems with HZ=100 can have slow bootup times due to the default
three-jiffy delays between quiescent-state forcing attempts. This
commit therefore auto-tunes the RCU_JIFFIES_TILL_FORCE_QS value based
on the value of HZ. However, this would break very large systems that
require more time between quiescent-state forcing attempts. This
commit therefore also ups the default delay by one jiffy for each
256 CPUs that might be on the system (based off of nr_cpu_ids at
runtime, -not- NR_CPUS at build time).
Updated to collapse #ifdefs for RCU_JIFFIES_TILL_FORCE_QS into a
step-function definition as suggested by Josh Triplett.
Reported-by: Paul Mackerras <paulus@au1.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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After a release or two, features are no longer experimental. Therefore,
this commit removes the "Experimental" tag from them.
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The kworker workqueue kthreads can also contribute to OS jitter.
The amount of jitter depends on their use, so this commit adds
documentation on avoiding OS jitter due to workqueue use.
Reported-by: Jonathan Clairembault <jonathan.clairembault@novasparks.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit calls out the potential for slowing the tick even when there
are multiple runnable processes per CPU, It also points out that current
mainlined version keeps the tick going on at least one CPU even when all
CPUs are otherwise idle. Finally, it notes the need for a 1-HZ tick in
order to calculate CPU load, maintain sched average, compute CFS entity
vruntime, compute avenrun, and carry out load balancing.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Make it more clear that there are three options, and give hints as
to which of the three is most likely to be useful in different
situations.
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The __rcu_process_callbacks() invokes note_gp_changes() immediately
before invoking rcu_check_quiescent_state(), which conditionally
invokes that same function. This commit therefore eliminates the
call to note_gp_changes() in __rcu_process_callbacks() in favor of
making unconditional to call from rcu_check_quiescent_state() to
note_gp_changes().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Given the changes that introduce note_gp_change(), rcu_start_gp_per_cpu()
is now a trivial wrapper function with only one caller. This commit
therefore inlines it into its sole call site.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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One of the calls to check_for_new_grace_period() is now redundant due to
an immediately preceding call to note_gp_changes(). Eliminating this
redundant call leaves a single caller, which is simpler if inlined.
This commit therefore eliminates the redundant call and inlines the
body of check_for_new_grace_period() into the single remaining call site.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit eliminates some duplicated code by merging
__rcu_process_gp_end() into __note_gp_changes().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Because note_gp_changes() now incorporates rcu_process_gp_end() function,
this commit switches to the former and eliminates the latter. In
addition, this commit changes external calls from __rcu_process_gp_end()
to __note_gp_changes().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit converts printk() calls to the corresponding pr_*() calls.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Because note_new_gpnum() now also checks for the ends of old grace periods,
this commit changes its name to note_gp_changes(). Later commits will merge
rcu_process_gp_end() into note_gp_changes().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The current implementation can detect the beginning of a new grace period
before noting the end of a previous grace period. Although the current
implementation correctly handles this sort of nonsense, it would be
good to reduce RCU's state space by making such nonsense unnecessary,
which is now possible thanks to the fact that RCU's callback groups are
now numbered.
This commit therefore makes __note_new_gpnum() invoke
__rcu_process_gp_end() in order to note the ends of prior grace
periods before noting the beginnings of new grace periods.
Of course, this now means that note_new_gpnum() notes both the
beginnings and ends of grace periods, and could therefore be
used in place of rcu_process_gp_end(). But that is a job for
later commits.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The addition of callback numbering allows combining the detection of the
ends of old grace periods and the beginnings of new grace periods. This
commit moves code to set the stage for this combining.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit converts printk() calls to the corresponding pr_*() calls.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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In Steven Rostedt's words:
> I've been debugging the last couple of days why my tests have been
> locking up. One of my tracing tests, runs all available tracers. The
> lockup always happened with the mmiotrace, which is used to trace
> interactions between priority drivers and the kernel. But to do this
> easily, when the tracer gets registered, it disables all but the boot
> CPUs. The lockup always happened after it got done disabling the CPUs.
>
> Then I decided to try this:
>
> while :; do
> for i in 1 2 3; do
> echo 0 > /sys/devices/system/cpu/cpu$i/online
> done
> for i in 1 2 3; do
> echo 1 > /sys/devices/system/cpu/cpu$i/online
> done
> done
>
> Well, sure enough, that locked up too, with the same users. Doing a
> sysrq-w (showing all blocked tasks):
>
> [ 2991.344562] task PC stack pid father
> [ 2991.344562] rcu_preempt D ffff88007986fdf8 0 10 2 0x00000000
> [ 2991.344562] ffff88007986fc98 0000000000000002 ffff88007986fc48 0000000000000908
> [ 2991.344562] ffff88007986c280 ffff88007986ffd8 ffff88007986ffd8 00000000001d3c80
> [ 2991.344562] ffff880079248a40 ffff88007986c280 0000000000000000 00000000fffd4295
> [ 2991.344562] Call Trace:
> [ 2991.344562] [<ffffffff815437ba>] schedule+0x64/0x66
> [ 2991.344562] [<ffffffff81541750>] schedule_timeout+0xbc/0xf9
> [ 2991.344562] [<ffffffff8154bec0>] ? ftrace_call+0x5/0x2f
> [ 2991.344562] [<ffffffff81049513>] ? cascade+0xa8/0xa8
> [ 2991.344562] [<ffffffff815417ab>] schedule_timeout_uninterruptible+0x1e/0x20
> [ 2991.344562] [<ffffffff810c980c>] rcu_gp_kthread+0x502/0x94b
> [ 2991.344562] [<ffffffff81062791>] ? __init_waitqueue_head+0x50/0x50
> [ 2991.344562] [<ffffffff810c930a>] ? rcu_gp_fqs+0x64/0x64
> [ 2991.344562] [<ffffffff81061cdb>] kthread+0xb1/0xb9
> [ 2991.344562] [<ffffffff81091e31>] ? lock_release_holdtime.part.23+0x4e/0x55
> [ 2991.344562] [<ffffffff81061c2a>] ? __init_kthread_worker+0x58/0x58
> [ 2991.344562] [<ffffffff8154c1dc>] ret_from_fork+0x7c/0xb0
> [ 2991.344562] [<ffffffff81061c2a>] ? __init_kthread_worker+0x58/0x58
> [ 2991.344562] kworker/0:1 D ffffffff81a30680 0 47 2 0x00000000
> [ 2991.344562] Workqueue: events cpuset_hotplug_workfn
> [ 2991.344562] ffff880078dbbb58 0000000000000002 0000000000000006 00000000000000d8
> [ 2991.344562] ffff880078db8100 ffff880078dbbfd8 ffff880078dbbfd8 00000000001d3c80
> [ 2991.344562] ffff8800779ca5c0 ffff880078db8100 ffffffff81541fcf 0000000000000000
> [ 2991.344562] Call Trace:
> [ 2991.344562] [<ffffffff81541fcf>] ? __mutex_lock_common+0x3d4/0x609
> [ 2991.344562] [<ffffffff815437ba>] schedule+0x64/0x66
> [ 2991.344562] [<ffffffff81543a39>] schedule_preempt_disabled+0x18/0x24
> [ 2991.344562] [<ffffffff81541fcf>] __mutex_lock_common+0x3d4/0x609
> [ 2991.344562] [<ffffffff8103d11b>] ? get_online_cpus+0x3c/0x50
> [ 2991.344562] [<ffffffff8103d11b>] ? get_online_cpus+0x3c/0x50
> [ 2991.344562] [<ffffffff815422ff>] mutex_lock_nested+0x3b/0x40
> [ 2991.344562] [<ffffffff8103d11b>] get_online_cpus+0x3c/0x50
> [ 2991.344562] [<ffffffff810af7e6>] rebuild_sched_domains_locked+0x6e/0x3a8
> [ 2991.344562] [<ffffffff810b0ec6>] rebuild_sched_domains+0x1c/0x2a
> [ 2991.344562] [<ffffffff810b109b>] cpuset_hotplug_workfn+0x1c7/0x1d3
> [ 2991.344562] [<ffffffff810b0ed9>] ? cpuset_hotplug_workfn+0x5/0x1d3
> [ 2991.344562] [<ffffffff81058e07>] process_one_work+0x2d4/0x4d1
> [ 2991.344562] [<ffffffff81058d3a>] ? process_one_work+0x207/0x4d1
> [ 2991.344562] [<ffffffff8105964c>] worker_thread+0x2e7/0x3b5
> [ 2991.344562] [<ffffffff81059365>] ? rescuer_thread+0x332/0x332
> [ 2991.344562] [<ffffffff81061cdb>] kthread+0xb1/0xb9
> [ 2991.344562] [<ffffffff81061c2a>] ? __init_kthread_worker+0x58/0x58
> [ 2991.344562] [<ffffffff8154c1dc>] ret_from_fork+0x7c/0xb0
> [ 2991.344562] [<ffffffff81061c2a>] ? __init_kthread_worker+0x58/0x58
> [ 2991.344562] bash D ffffffff81a4aa80 0 2618 2612 0x10000000
> [ 2991.344562] ffff8800379abb58 0000000000000002 0000000000000006 0000000000000c2c
> [ 2991.344562] ffff880077fea140 ffff8800379abfd8 ffff8800379abfd8 00000000001d3c80
> [ 2991.344562] ffff8800779ca5c0 ffff880077fea140 ffffffff81541fcf 0000000000000000
> [ 2991.344562] Call Trace:
> [ 2991.344562] [<ffffffff81541fcf>] ? __mutex_lock_common+0x3d4/0x609
> [ 2991.344562] [<ffffffff815437ba>] schedule+0x64/0x66
> [ 2991.344562] [<ffffffff81543a39>] schedule_preempt_disabled+0x18/0x24
> [ 2991.344562] [<ffffffff81541fcf>] __mutex_lock_common+0x3d4/0x609
> [ 2991.344562] [<ffffffff81530078>] ? rcu_cpu_notify+0x2f5/0x86e
> [ 2991.344562] [<ffffffff81530078>] ? rcu_cpu_notify+0x2f5/0x86e
> [ 2991.344562] [<ffffffff815422ff>] mutex_lock_nested+0x3b/0x40
> [ 2991.344562] [<ffffffff81530078>] rcu_cpu_notify+0x2f5/0x86e
> [ 2991.344562] [<ffffffff81091c99>] ? __lock_is_held+0x32/0x53
> [ 2991.344562] [<ffffffff81548912>] notifier_call_chain+0x6b/0x98
> [ 2991.344562] [<ffffffff810671fd>] __raw_notifier_call_chain+0xe/0x10
> [ 2991.344562] [<ffffffff8103cf64>] __cpu_notify+0x20/0x32
> [ 2991.344562] [<ffffffff8103cf8d>] cpu_notify_nofail+0x17/0x36
> [ 2991.344562] [<ffffffff815225de>] _cpu_down+0x154/0x259
> [ 2991.344562] [<ffffffff81522710>] cpu_down+0x2d/0x3a
> [ 2991.344562] [<ffffffff81526351>] store_online+0x4e/0xe7
> [ 2991.344562] [<ffffffff8134d764>] dev_attr_store+0x20/0x22
> [ 2991.344562] [<ffffffff811b3c5f>] sysfs_write_file+0x108/0x144
> [ 2991.344562] [<ffffffff8114c5ef>] vfs_write+0xfd/0x158
> [ 2991.344562] [<ffffffff8114c928>] SyS_write+0x5c/0x83
> [ 2991.344562] [<ffffffff8154c494>] tracesys+0xdd/0xe2
>
> As well as held locks:
>
> [ 3034.728033] Showing all locks held in the system:
> [ 3034.728033] 1 lock held by rcu_preempt/10:
> [ 3034.728033] #0: (rcu_preempt_state.onoff_mutex){+.+...}, at: [<ffffffff810c9471>] rcu_gp_kthread+0x167/0x94b
> [ 3034.728033] 4 locks held by kworker/0:1/47:
> [ 3034.728033] #0: (events){.+.+.+}, at: [<ffffffff81058d3a>] process_one_work+0x207/0x4d1
> [ 3034.728033] #1: (cpuset_hotplug_work){+.+.+.}, at: [<ffffffff81058d3a>] process_one_work+0x207/0x4d1
> [ 3034.728033] #2: (cpuset_mutex){+.+.+.}, at: [<ffffffff810b0ec1>] rebuild_sched_domains+0x17/0x2a
> [ 3034.728033] #3: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff8103d11b>] get_online_cpus+0x3c/0x50
> [ 3034.728033] 1 lock held by mingetty/2563:
> [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8131e28a>] n_tty_read+0x252/0x7e8
> [ 3034.728033] 1 lock held by mingetty/2565:
> [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8131e28a>] n_tty_read+0x252/0x7e8
> [ 3034.728033] 1 lock held by mingetty/2569:
> [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8131e28a>] n_tty_read+0x252/0x7e8
> [ 3034.728033] 1 lock held by mingetty/2572:
> [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8131e28a>] n_tty_read+0x252/0x7e8
> [ 3034.728033] 1 lock held by mingetty/2575:
> [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8131e28a>] n_tty_read+0x252/0x7e8
> [ 3034.728033] 7 locks held by bash/2618:
> [ 3034.728033] #0: (sb_writers#5){.+.+.+}, at: [<ffffffff8114bc3f>] file_start_write+0x2a/0x2c
> [ 3034.728033] #1: (&buffer->mutex#2){+.+.+.}, at: [<ffffffff811b3b93>] sysfs_write_file+0x3c/0x144
> [ 3034.728033] #2: (s_active#54){.+.+.+}, at: [<ffffffff811b3c3e>] sysfs_write_file+0xe7/0x144
> [ 3034.728033] #3: (x86_cpu_hotplug_driver_mutex){+.+.+.}, at: [<ffffffff810217c2>] cpu_hotplug_driver_lock+0x17/0x19
> [ 3034.728033] #4: (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff8103d196>] cpu_maps_update_begin+0x17/0x19
> [ 3034.728033] #5: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff8103cfd8>] cpu_hotplug_begin+0x2c/0x6d
> [ 3034.728033] #6: (rcu_preempt_state.onoff_mutex){+.+...}, at: [<ffffffff81530078>] rcu_cpu_notify+0x2f5/0x86e
> [ 3034.728033] 1 lock held by bash/2980:
> [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8131e28a>] n_tty_read+0x252/0x7e8
>
> Things looked a little weird. Also, this is a deadlock that lockdep did
> not catch. But what we have here does not look like a circular lock
> issue:
>
> Bash is blocked in rcu_cpu_notify():
>
> 1961 /* Exclude any attempts to start a new grace period. */
> 1962 mutex_lock(&rsp->onoff_mutex);
>
>
> kworker is blocked in get_online_cpus(), which makes sense as we are
> currently taking down a CPU.
>
> But rcu_preempt is not blocked on anything. It is simply sleeping in
> rcu_gp_kthread (really rcu_gp_init) here:
>
> 1453 #ifdef CONFIG_PROVE_RCU_DELAY
> 1454 if ((prandom_u32() % (rcu_num_nodes * 8)) == 0 &&
> 1455 system_state == SYSTEM_RUNNING)
> 1456 schedule_timeout_uninterruptible(2);
> 1457 #endif /* #ifdef CONFIG_PROVE_RCU_DELAY */
>
> And it does this while holding the onoff_mutex that bash is waiting for.
>
> Doing a function trace, it showed me where it happened:
>
> [ 125.940066] rcu_pree-10 3.... 28384115273: schedule_timeout_uninterruptible <-rcu_gp_kthread
> [...]
> [ 125.940066] rcu_pree-10 3d..3 28384202439: sched_switch: prev_comm=rcu_preempt prev_pid=10 prev_prio=120 prev_state=D ==> next_comm=watchdog/3 next_pid=38 next_prio=120
>
> The watchdog ran, and then:
>
> [ 125.940066] watchdog-38 3d..3 28384692863: sched_switch: prev_comm=watchdog/3 prev_pid=38 prev_prio=120 prev_state=P ==> next_comm=modprobe next_pid=2848 next_prio=118
>
> Not sure what modprobe was doing, but shortly after that:
>
> [ 125.940066] modprobe-2848 3d..3 28385041749: sched_switch: prev_comm=modprobe prev_pid=2848 prev_prio=118 prev_state=R+ ==> next_comm=migration/3 next_pid=40 next_prio=0
>
> Where the migration thread took down the CPU:
>
> [ 125.940066] migratio-40 3d..3 28389148276: sched_switch: prev_comm=migration/3 prev_pid=40 prev_prio=0 prev_state=P ==> next_comm=swapper/3 next_pid=0 next_prio=120
>
> which finally did:
>
> [ 125.940066] <idle>-0 3...1 28389282142: arch_cpu_idle_dead <-cpu_startup_entry
> [ 125.940066] <idle>-0 3...1 28389282548: native_play_dead <-arch_cpu_idle_dead
> [ 125.940066] <idle>-0 3...1 28389282924: play_dead_common <-native_play_dead
> [ 125.940066] <idle>-0 3...1 28389283468: idle_task_exit <-play_dead_common
> [ 125.940066] <idle>-0 3...1 28389284644: amd_e400_remove_cpu <-play_dead_common
>
>
> CPU 3 is now offline, the rcu_preempt thread that ran on CPU 3 is still
> doing a schedule_timeout_uninterruptible() and it registered it's
> timeout to the timer base for CPU 3. You would think that it would get
> migrated right? The issue here is that the timer migration happens at
> the CPU notifier for CPU_DEAD. The problem is that the rcu notifier for
> CPU_DOWN is blocked waiting for the onoff_mutex to be released, which is
> held by the thread that just put itself into a uninterruptible sleep,
> that wont wake up until the CPU_DEAD notifier of the timer
> infrastructure is called, which wont happen until the rcu notifier
> finishes. Here's our deadlock!
This commit breaks this deadlock cycle by substituting a shorter udelay()
for the previous schedule_timeout_uninterruptible(), while at the same
time increasing the probability of the delay. This maintains the intensity
of the testing.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
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