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Unbound wqs aren't concurrency-managed and try to execute work items
as soon as possible. This is currently achieved by implicitly setting
%WQ_HIGHPRI on all unbound workqueues; however, WQ_HIGHPRI
implementation is about to be restructured and this usage won't be
valid anymore.
Add an explicit chain-wakeup path for unbound workqueues in
process_one_work() instead of piggy backing on %WQ_HIGHPRI.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Clean up and return -ENOMEM on if the kzalloc() fails.
This also prevents a potential crash, as the pointer that failed to
allocate would be later used.
Link: http://lkml.kernel.org/r/20120711063507.GF11812@elgon.mountain
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Merge random patches from Andrew Morton.
* Merge emailed patches from Andrew Morton <akpm@linux-foundation.org>: (32 commits)
memblock: free allocated memblock_reserved_regions later
mm: sparse: fix usemap allocation above node descriptor section
mm: sparse: fix section usemap placement calculation
xtensa: fix incorrect memset
shmem: cleanup shmem_add_to_page_cache
shmem: fix negative rss in memcg memory.stat
tmpfs: revert SEEK_DATA and SEEK_HOLE
drivers/rtc/rtc-twl.c: fix threaded IRQ to use IRQF_ONESHOT
fat: fix non-atomic NFS i_pos read
MAINTAINERS: add OMAP CPUfreq driver to OMAP Power Management section
sgi-xp: nested calls to spin_lock_irqsave()
fs: ramfs: file-nommu: add SetPageUptodate()
drivers/rtc/rtc-mxc.c: fix irq enabled interrupts warning
mm/memory_hotplug.c: release memory resources if hotadd_new_pgdat() fails
h8300/uaccess: add mising __clear_user()
h8300/uaccess: remove assignment to __gu_val in unhandled case of get_user()
h8300/time: add missing #include <asm/irq_regs.h>
h8300/signal: fix typo "statis"
h8300/pgtable: add missing #include <asm-generic/pgtable.h>
drivers/rtc/rtc-ab8500.c: ensure correct probing of the AB8500 RTC when Device Tree is enabled
...
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"no other files mapped" requirement from my previous patch (c/r: prctl:
update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal) is too
paranoid, it forbids operation even if there mapped one shared-anon vma.
Let's check that current mm->exe_file already unmapped, in this case
exe_file symlink already outdated and its changing is reasonable.
Plus, this patch fixes exit code in case operation success.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The update of the hrtimer base offsets on all cpus cannot be made
atomically from the timekeeper.lock held and interrupt disabled region
as smp function calls are not allowed there.
clock_was_set(), which enforces the update on all cpus, is called
either from preemptible process context in case of do_settimeofday()
or from the softirq context when the offset modification happened in
the timer interrupt itself due to a leap second.
In both cases there is a race window for an hrtimer interrupt between
dropping timekeeper lock, enabling interrupts and clock_was_set()
issuing the updates. Any interrupt which arrives in that window will
see the new time but operate on stale offsets.
So we need to make sure that an hrtimer interrupt always sees a
consistent state of time and offsets.
ktime_get_update_offsets() allows us to get the current monotonic time
and update the per cpu hrtimer base offsets from hrtimer_interrupt()
to capture a consistent state of monotonic time and the offsets. The
function replaces the existing ktime_get() calls in hrtimer_interrupt().
The overhead of the new function vs. ktime_get() is minimal as it just
adds two store operations.
This ensures that any changes to realtime or boottime offsets are
noticed and stored into the per-cpu hrtimer base structures, prior to
any hrtimer expiration and guarantees that timers are not expired early.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-8-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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To finally fix the infamous leap second issue and other race windows
caused by functions which change the offsets between the various time
bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a
function which atomically gets the current monotonic time and updates
the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic
overhead. The previous patch which provides ktime_t offsets allows us
to make this function almost as cheap as ktime_get() which is going to
be replaced in hrtimer_interrupt().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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We need to update the base offsets from this code and we need to do
that under base->lock. Move the lock held region around the
ktime_get() calls. The ktime_get() calls are going to be replaced with
a function which gets the time and the offsets atomically.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-6-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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We need to update the hrtimer clock offsets from the hrtimer interrupt
context. To avoid conversions from timespec to ktime_t maintain a
ktime_t based representation of those offsets in the timekeeper. This
puts the conversion overhead into the code which updates the
underlying offsets and provides fast accessible values in the hrtimer
interrupt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-4-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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The timekeeping code misses an update of the hrtimer subsystem after a
leap second happened. Due to that timers based on CLOCK_REALTIME are
either expiring a second early or late depending on whether a leap
second has been inserted or deleted until an operation is initiated
which causes that update. Unless the update happens by some other
means this discrepancy between the timekeeping and the hrtimer data
stays forever and timers are expired either early or late.
The reported immediate workaround - $ data -s "`date`" - is causing a
call to clock_was_set() which updates the hrtimer data structures.
See: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix
Add the missing clock_was_set() call to update_wall_time() in case of
a leap second event. The actual update is deferred to softirq context
as the necessary smp function call cannot be invoked from hard
interrupt context.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-3-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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clock_was_set() cannot be called from hard interrupt context because
it calls on_each_cpu().
For fixing the widely reported leap seconds issue it is necessary to
call it from hard interrupt context, i.e. the timer tick code, which
does the timekeeping updates.
Provide a new function which denotes it in the hrtimer cpu base
structure of the cpu on which it is called and raise the hrtimer
softirq. We then execute the clock_was_set() notificiation from
softirq context in run_hrtimer_softirq(). The hrtimer softirq is
rarely used, so polling the flag there is not a performance issue.
[ tglx: Made it depend on CONFIG_HIGH_RES_TIMERS. We really should get
rid of all this ifdeffery ASAP ]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-2-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull printk fixes from Greg Kroah-Hartman:
"Here are some more printk fixes for 3.5-rc6. They resolve all known
outstanding issues with the printk changes that have been happening.
They have been tested by the people reporting the problems.
This hopefully should be it for the printk stuff for 3.5-final.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>"
* tag 'driver-core-3.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
kmsg: merge continuation records while printing
kmsg: /proc/kmsg - support reading of partial log records
kmsg: make sure all messages reach a newly registered boot console
kmsg: properly handle concurrent non-blocking read() from /proc/kmsg
kmsg: add the facility number to the syslog prefix
kmsg: escape the backslash character while exporting data
printk: replacing the raw_spin_lock/unlock with raw_spin_lock/unlock_irq
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irq_create_direct_mapping can only be used with the NOMAP type. Make
the function test to ensure it is passed the correct type of
irq_domain.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <rob.herring@calxeda.com>
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In preparation to remove the slow revmap path, eliminate the public
radix revmap lookup functions. This simplifies the code and makes the
slowpath removal patch a lot simpler.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <rob.herring@calxeda.com>
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This adds a new strict mapping API for supporting creation of linux IRQs
at existing positions within the domain. The new routines are as follows:
For dynamic allocation and insertion to specified ranges:
- irq_create_identity_mapping()
- irq_create_strict_mappings()
These will allocate and associate a range of linux IRQs at the specified
location. This can be used by controllers that have their own static linux IRQ
definitions to map a hwirq range to, as well as for platforms that wish to
establish 1:1 identity mapping between linux and hwirq space.
For insertion to specified ranges by platforms that do their own irq_desc
management:
- irq_domain_associate()
- irq_domain_associate_many()
These in turn call back in to the domain's ->map() routine, for further
processing by the platform. Disassociation of IRQs get handled through
irq_dispose_mapping() as normal.
With these in place it should be possible to begin migration of legacy IRQ
domains to linear ones, without requiring special handling for static vs
dynamic IRQ definitions in DT vs non-DT paths. This also makes it possible
for domains with static mappings to adopt whichever tree model best fits
their needs, rather than simply restricting them to linear revmaps.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
[grant.likely: Reorganized irq_domain_associate{,_many} to have all logic in one place]
[grant.likely: Add error checking for unallocated irq_descs at associate time]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <rob.herring@calxeda.com>
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At irq_setup_virq() time all of the data needed to update the reverse
map is available, but the current code ignores it and relies upon the
slow path to insert revmap records. This patch adds revmap updating
to the setup path so the slow path will no longer be necessary.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <rob.herring@calxeda.com>
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This patch moves the irq disassociation code out into a separate
function in preparation to extend irq_setup_virq to handle multiple
irqs and rename it for use by interrupt controller drivers. The new
function will be used by irq_setup_virq() in its error path.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <rob.herring@calxeda.com>
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Linux 3.5-rc6
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The revmap type should be linear for irq_domain_add_linear function.
Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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A large proportion of interrupt controllers that support legacy mappings
do so because non-DT systems need to use fixed IRQ numbers when registering
devices via buses but can otherwise use a linear mapping. The interrupt
controller itself typically is not affected by the mapping used and best
practice is to use a linear mapping where possible so drivers frequently
select at runtime depending on if a legacy range has been allocated to
them.
Standardise this behaviour by providing irq_domain_register_simple() which
will allocate a linear mapping unless a positive first_irq is provided in
which case it will fall back to a legacy mapping. This helps make best
practice for irq_domain adoption clearer.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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In (the unlikely) case our continuation merge buffer is busy, we unfortunately
can not merge further continuation printk()s into a single record and have to
store them separately, which leads to split-up output of these lines when they
are printed.
Add some flags about newlines and prefix existence to these records and try to
reconstruct the full line again, when the separated records are printed.
Reported-By: Michael Neuling <mikey@neuling.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Tested-By: Michael Neuling <mikey@neuling.org>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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While refactoring cgroup file removal path, 05ef1d7c4a "cgroup:
introduce struct cfent" incorrectly changed the @dir argument of
simple_unlink() to the inode of the file being deleted instead of that
of the containing directory.
The effect of this bug is minor - ctime and mtime of the parent
weren't properly updated on file deletion.
Fix it by using @cgrp->dentry->d_inode instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
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Restore support for partial reads of any size on /proc/kmsg, in case the
supplied read buffer is smaller than the record size.
Some people seem to think is is ia good idea to run:
$ dd if=/proc/kmsg bs=1 of=...
as a klog bridge.
Resolves-bug: https://bugzilla.kernel.org/show_bug.cgi?id=44211
Reported-by: Jukka Ollila <jiiksteri@gmail.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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48ddbe1946 "cgroup: make css->refcnt clearing on cgroup removal
optional" allowed a css to linger after the associated cgroup is
removed. As a css holds a reference on the cgroup's dentry, it means
that cgroup dentries may linger for a while.
Destroying a superblock which has dentries with positive refcnts is a
critical bug and triggers BUG() in vfs code. As each cgroup dentry
holds an s_active reference, any lingering cgroup has both its dentry
and the superblock pinned and thus preventing premature release of
superblock.
Unfortunately, after 48ddbe1946, there's a small window while
releasing a cgroup which is directly under the root of the hierarchy.
When a cgroup directory is released, vfs layer first deletes the
corresponding dentry and then invokes dput() on the parent, which may
recurse further, so when a cgroup directly below root cgroup is
released, the cgroup is first destroyed - which releases the s_active
it was holding - and then the dentry for the root cgroup is dput().
This creates a window where the root dentry's refcnt isn't zero but
superblock's s_active is. If umount happens before or during this
window, vfs will see the root dentry with non-zero refcnt and trigger
BUG().
Before 48ddbe1946, this problem didn't exist because the last dentry
reference was guaranteed to be put synchronously from rmdir(2)
invocation which holds s_active around the whole process.
Fix it by holding an extra superblock->s_active reference across
dput() from css release, which is the dput() path added by 48ddbe1946
and the only one which doesn't hold an extra s_active ref across the
final cgroup dput().
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <4FEEA5CB.8070809@huawei.com>
Reported-by: shyju pv <shyju.pv@huawei.com>
Tested-by: shyju pv <shyju.pv@huawei.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Acked-by: Li Zefan <lizefan@huawei.com>
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This reverts commit fa980ca87d15bb8a1317853f257a505990f3ffde. The
commit was an attempt to fix a race condition where a cgroup hierarchy
may be unmounted with positive dentry reference on root cgroup. While
the commit made the race condition slightly more difficult to trigger,
the race was still there and could be reliably triggered using a
different test case.
Revert the incorrect fix. The next commit will describe the race and
fix it correctly.
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <4FEEA5CB.8070809@huawei.com>
Reported-by: shyju pv <shyju.pv@huawei.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Acked-by: Li Zefan <lizefan@huawei.com>
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We suppress printing kmsg records to the console, which are already printed
immediately while we have received their fragments.
Newly registered boot consoles print the entire kmsg buffer during
registration. Clear the console-suppress flag after we skipped the record
during its first storage, so any later print will see these records as usual.
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The /proc/kmsg read() interface is internally simply wired up to a sequence
of syslog() syscalls, which might are racy between their checks and actions,
regarding concurrency.
In the (very uncommon) case of concurrent readers of /dev/kmsg, relying on
usual O_NONBLOCK behavior, the recently introduced mutex might block an
O_NONBLOCK reader in read(), when poll() returns for it, but another process
has already read the data in the meantime. We've seen that while running
artificial test setups and tools that "fight" about /proc/kmsg data.
This restores the original /proc/kmsg behavior, where in case of concurrent
read()s, poll() might wake up but the read() syscall will just return 0 to
the caller, while another process has "stolen" the data.
This is in the general case not the expected behavior, but it is the exact
same one, that can easily be triggered with a 3.4 kernel, and some tools
might just rely on it.
The mutex is not needed, the original integrity issue which introduced it,
is in the meantime covered by:
"fill buffer with more than a single message for SYSLOG_ACTION_READ"
116e90b23f74d303e8d607c7a7d54f60f14ab9f2
Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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After the recent split of facility and level into separate variables,
we miss the facility value (always 0 for kernel-originated messages)
in the syslog prefix.
On Tue, Jul 3, 2012 at 12:45 PM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> Static checkers complain about the impossible condition here.
>
> In 084681d14e ('printk: flush continuation lines immediately to
> console'), we changed msg->level from being a u16 to being an unsigned
> 3 bit bitfield.
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Non-printable characters in the log data are hex-escaped to ensure safe
post processing. We need to escape a backslash we find in the data, to be
able to distinguish it from a backslash we add for the escaping.
Also escape the non-printable character 127.
Thanks to Miloslav Trmac for the heads up.
Reported-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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In function devkmsg_read/writev/llseek/poll/open()..., the function
raw_spin_lock/unlock is used, there is potential deadlock case happening.
CPU1: thread1 doing the cat /dev/kmsg:
raw_spin_lock(&logbuf_lock);
while (user->seq == log_next_seq) {
when thread1 run here, at this time one interrupt is coming on CPU1 and running
based on this thread,if the interrupt handle called the printk which need the
logbuf_lock spin also, it will cause deadlock.
So we should use raw_spin_lock/unlock_irq here.
Acked-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull the RCU tree from Paul E. McKenney:
"The major features of this series are:
1. Preventing latency spikes of more than 200 microseconds for
kernels built with NR_CPUS=4096, which is reportedly becoming
the default for some distros. This is a first step, as it does
not help with systems that actually -have- 4096 CPUs (work on
this case is in progress, but is not yet ready for mainline).
This category also includes improving concurrency of rcu_barrier(),
placed here due to conflicts. Posted to LKML at:
https://lkml.org/lkml/2012/6/22/381. Note that patches 18-22
of that series have been defered to 3.7, as they have not yet
proven themselves to be mainline-ready (and yes, these are the
ones intended to get rid of RCU's latency spikes for systems
that actually have 4096 CPUs).
2. Updates to documentation and rcutorture fixes, the latter category
including improvements to rcu_barrier() testing. Posted to LKML at:
http://lkml.indiana.edu/hypermail/linux/kernel/1206.1/04094.html.
3. Miscellaneous fixes posted to LKML at:
https://lkml.org/lkml/2012/6/22/500, with the exception of the
last commit, which was posted here:
http://www.gossamer-threads.com/lists/linux/kernel/1561830
4. RCU_FAST_NO_HZ fixes and improvements. Posted to LKML at:
http://lkml.indiana.edu/hypermail/linux/kernel/1206.1/00006.html
and http://www.gossamer-threads.com/lists/linux/kernel/1561833.
The first four patches of the first series went into 3.5 to fix
a regression.
5. Code-style fixes. These were posted to LKML at
http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/01180.html and
http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/01181.html.
"
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Although the C language allows you to break strings across lines, doing
this makes it hard for people to find the Linux kernel code corresponding
to a given console message. This commit therefore fixes broken strings
throughout RCU's source code.
Suggested-by: Josh Triplett <josh@joshtriplett.org>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The Linux kernel coding style says that single-statement blocks should
omit curly braces unless the other leg of the "if" statement has
multiple statements, in which case the curly braces should be included.
This commit fixes RCU's violations of this rule.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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'fixes.2012.07.06a' and 'fnh.2012.07.02a' into HEAD
bigrtm: First steps towards getting RCU out of the way of
tens-of-microseconds real-time response on systems compiled
with NR_CPUS=4096. Also cleanups for and increased concurrency
of rcu_barrier() family of primitives.
doctorture: rcutorture and documentation improvements.
fixes: Miscellaneous fixes.
fnh: RCU_FAST_NO_HZ fixes and improvements.
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The recent bug that introduced the RCU callback list/count mismatch
showed the need for a diagnostic to check for this, which this commit
adds.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The pattern (np ? np->full_name : "<none>") is rather common in the
kernel, but can also make for quite long lines. This patch adds a new
inline function, of_node_full_name() so that the test for a valid node
pointer doesn't need to be open coded at all call sites.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent
Pull low probability CONFIG_RCU_BOOST=y deadlock fix from Paul E. McKenney.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core
Pull tracing updates from Steve Rostedt.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge this branch to pick up a fixlet and to update to a more recent base.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Thanks to Charles Wang for spotting the defects in the current code:
- If we go idle during the sample window -- after sampling, we get a
negative bias because we can negate our own sample.
- If we wake up during the sample window we get a positive bias
because we push the sample to a known active period.
So rewrite the entire nohz load-avg muck once again, now adding
copious documentation to the code.
Reported-and-tested-by: Doug Smythies <dsmythies@telus.net>
Reported-and-tested-by: Charles Wang <muming.wq@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1340373782.18025.74.camel@twins
[ minor edits ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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In dup_task_struct(), if arch_dup_task_struct() fails, the clean up
code fails to clean up correctly. That's because the clean up
code depends on unininitalized ti->task pointer. We fix this
by making sure that the task and thread_info know about each other
before we attempt to take the error path.
Signed-off-by: Salman Qazi <sqazi@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120626011815.11323.5533.stgit@dungbeetle.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Pull block bits from Jens Axboe:
"As vacation is coming up, thought I'd better get rid of my pending
changes in my for-linus branch for this iteration. It contains:
- Two patches for mtip32xx. Killing a non-compliant sysfs interface
and moving it to debugfs, where it belongs.
- A few patches from Asias. Two legit bug fixes, and one killing an
interface that is no longer in use.
- A patch from Jan, making the annoying partition ioctl warning a bit
less annoying, by restricting it to !CAP_SYS_RAWIO only.
- Three bug fixes for drbd from Lars Ellenberg.
- A fix for an old regression for umem, it hasn't really worked since
the plugging scheme was changed in 3.0.
- A few fixes from Tejun.
- A splice fix from Eric Dumazet, fixing an issue with pipe
resizing."
* 'for-linus' of git://git.kernel.dk/linux-block:
scsi: Silence unnecessary warnings about ioctl to partition
block: Drop dead function blk_abort_queue()
block: Mitigate lock unbalance caused by lock switching
block: Avoid missed wakeup in request waitqueue
umem: fix up unplugging
splice: fix racy pipe->buffers uses
drbd: fix null pointer dereference with on-congestion policy when diskless
drbd: fix list corruption by failing but already aborted reads
drbd: fix access of unallocated pages and kernel panic
xen/blkfront: Add WARN to deal with misbehaving backends.
blkcg: drop local variable @q from blkg_destroy()
mtip32xx: Create debugfs entries for troubleshooting
mtip32xx: Remove 'registers' and 'flags' from sysfs
blkcg: fix blkg_alloc() failure path
block: blkcg_policy_cfq shouldn't be used if !CONFIG_CFQ_GROUP_IOSCHED
block: fix return value on cfq_init() failure
mtip32xx: Remove version.h header file inclusion
xen/blkback: Copy id field when doing BLKIF_DISCARD.
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If the nohz= boot parameter disables nohz, then RCU_FAST_NO_HZ needs to
also disable itself. This commit therefore checks for tick_nohz_enabled
being zero, disabling rcu_prepare_for_idle() if so. This commit assumes
that tick_nohz_enabled can change at runtime: If this is not the case,
then a simpler approach suffices.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Currently, if several CPUs in the same package have all lazy RCU
callbacks, their wakeups will be uncorrelated. If all the CPUs are in the
same power domain (as is often the case), this will result in unnecessary
power-ups of the package. This commit therefore uses round_jiffies()
to round the timeouts to a second boundary, increasing the odds that
they can be coalesced with each other or with other timeouts.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The TINY_PREEMPT_RCU() function rcu_preempt_needs_cpu(), which is called
from rcu_needs_cpu(), assumes that it is in a quiescent state with respect
to the CPU. This is no longer the case. This commit therefore updates
rcu_preempt_needs_cpu() to make it aware that it is not running in a
quiescent state.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>
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Problems in RCU idle entry and exit are almost always confined to the
offending CPU. This commit therefore switches ftrace_dump() from
DUMP_ALL to DUMP_ORIG.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>
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If a CPU goes offline with callbacks queued, those callbacks might be
indefinitely postponed, which can result in a system hang. This commit
therefore inserts warnings for this condition.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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It is time to optimize CONFIG_TREE_PREEMPT_RCU's synchronize_rcu()
for uniprocessor optimization, which means that rcu_blocking_is_gp()
can no longer rely on RCU read-side critical sections having disabled
preemption. This commit therefore disables preemption across
rcu_blocking_is_gp()'s scan of the cpu_online_mask.
(Updated from previous version to fix embarrassing bug spotted by
Wu Fengguang.)
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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An uninitialized string may be displayed at the end of the rcu_preempt
detected stall info such as
0: (1 GPs behind) idle=075/140000000000000/0 =8?^D=8?^D
^^^^^^^^^^
if CONFIG_RCU_FAST_NO_HZ is not defined.
This trivial patch clears the string in this case.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The rcu_is_cpu_idle() function is used if CONFIG_DEBUG_LOCK_ALLOC,
but TINY_RCU defines it only when CONFIG_PROVE_RCU. This causes
build failures when CONFIG_DEBUG_LOCK_ALLOC=y but CONFIG_PROVE_RCU=n.
This commit therefore adjusts the #ifdefs for rcu_is_cpu_idle() so
that it is defined when CONFIG_DEBUG_LOCK_ALLOC=y.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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