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git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull RCU fixes from Paul McKenney:
"I must confess that this past merge window was not RCU's best showing.
This series contains three more fixes for RCU regressions:
1. A fix to __DECLARE_TRACE_RCU() that causes it to act as an
interrupt from idle rather than as a task switch from idle.
This change is needed due to the recent use of _rcuidle()
tracepoints that can be invoked from interrupt handlers as well
as from idle. Without this fix, invoking _rcuidle() tracepoints
from interrupt handlers results in splats and (more seriously)
confusion on RCU's part as to whether a given CPU is idle or not.
This confusion can in turn result in too-short grace periods and
therefore random memory corruption.
2. A fix to a subtle deadlock that could result due to RCU doing
a wakeup while holding one of its rcu_node structure's locks.
Although the probability of occurrence is low, it really
does happen. The fix, courtesy of Steven Rostedt, uses
irq_work_queue() to avoid the deadlock.
3. A fix to a silent deadlock (invisible to lockdep) due to the
interaction of timeouts posted by RCU debug code enabled by
CONFIG_PROVE_RCU_DELAY=y, grace-period initialization, and CPU
hotplug operations. This will not occur in production kernels,
but really does occur in randconfig testing. Diagnosis courtesy
of Steven Rostedt"
* 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
rcu: Fix deadlock with CPU hotplug, RCU GP init, and timer migration
rcu: Don't call wakeup() with rcu_node structure ->lock held
trace: Allow idle-safe tracepoints to be called from irq
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cgroup->count tracks the number of css_sets associated with the cgroup
and used only to verify that no css_set is associated when the cgroup
is being destroyed. It's superflous as the destruction path can
simply check whether cgroup->cset_links is empty instead.
Drop cgroup->count and check ->cset_links directly from
cgroup_destroy_locked().
Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Li Zefan <[email protected]>
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__put_css_set() does RCU read access on @cgrp across dropping
@cgrp->count so that it can continue accessing @cgrp even if the count
reached zero and destruction of the cgroup commenced. Given that both
sides - __css_put() and cgroup_destroy_locked() - are cold paths, this
is unnecessary. Just making cgroup_destroy_locked() grab css_set_lock
while checking @cgrp->count is enough.
Remove the RCU read locking from __put_css_set() and make
cgroup_destroy_locked() read-lock css_set_lock when checking
@cgrp->count. This will also allow removing @cgrp->count.
Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Li Zefan <[email protected]>
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We will add another flag indicating that the cgroup is in the process
of being killed. REMOVING / REMOVED is more difficult to distinguish
and cgroup_is_removing()/cgroup_is_removed() are a bit awkward. Also,
later percpu_ref usage will involve "kill"ing the refcnt.
s/CGRP_REMOVED/CGRP_DEAD/
s/cgroup_is_removed()/cgroup_is_dead()
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Li Zefan <[email protected]>
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There's no point in using kmalloc() instead of the clearing variant
for trivial stuff. We can live dangerously elsewhere. Use kzalloc()
instead and drop 0 inits.
While at it, do trivial code reorganization in cgroup_file_open().
This patch doesn't introduce any functional changes.
v2: I was caught in the very distant past where list_del() didn't
poison and the initial version converted list_del()s to
list_del_init()s too. Li and Kent took me out of the stasis
chamber.
Signed-off-by: Tejun Heo <[email protected]>
Cc: Kent Overstreet <[email protected]>
Acked-by: Li Zefan <[email protected]>
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cgroups and css_sets are mapped M:N and this M:N mapping is
represented by struct cg_cgroup_link which forms linked lists on both
sides. The naming around this mapping is already confusing and struct
cg_cgroup_link exacerbates the situation quite a bit.
>From cgroup side, it starts off ->css_sets and runs through
->cgrp_link_list. From css_set side, it starts off ->cg_links and
runs through ->cg_link_list. This is rather reversed as
cgrp_link_list is used to iterate css_sets and cg_link_list cgroups.
Also, this is the only place which is still using the confusing "cg"
for css_sets. This patch cleans it up a bit.
* s/cgroup->css_sets/cgroup->cset_links/
s/css_set->cg_links/css_set->cgrp_links/
s/cgroup_iter->cg_link/cgroup_iter->cset_link/
* s/cg_cgroup_link/cgrp_cset_link/
* s/cgrp_cset_link->cg/cgrp_cset_link->cset/
s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/
s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/
* s/init_css_set_link/init_cgrp_cset_link/
s/free_cg_links/free_cgrp_cset_links/
s/allocate_cg_links/allocate_cgrp_cset_links/
* s/cgl[12]/link[12]/ in compare_css_sets()
* s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar
adustments.
* Comment and whiteline adjustments.
After the changes, we have
list_for_each_entry(link, &cont->cset_links, cset_link) {
struct css_set *cset = link->cset;
instead of
list_for_each_entry(link, &cont->css_sets, cgrp_link_list) {
struct css_set *cset = link->cg;
This patch is purely cosmetic.
v2: Fix broken sentences in the patch description.
Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Li Zefan <[email protected]>
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cgroup.c uses @cg for most struct css_set variables, which in itself
could be a bit confusing, but made much worse by the fact that there
are places which use @cg for struct cgroup variables.
compare_css_sets() epitomizes this confusion - @[old_]cg are struct
css_set while @cg[12] are struct cgroup.
It's not like the whole deal with cgroup, css_set and cg_cgroup_link
isn't already confusing enough. Let's give it some sanity by
uniformly using @cset for all struct css_set variables.
* s/cg/cset/ for all css_set variables.
* s/oldcg/old_cset/ s/oldcgrp/old_cgrp/. The same for the ones
prefixed with "new".
* s/cg/cgrp/ for cgroup variables in compare_css_sets().
* s/css/cset/ for the cgroup variable in task_cgroup_from_root().
* Whiteline adjustments.
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Li Zefan <[email protected]>
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Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Li Zefan <[email protected]>
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Before moving tasks out of empty cpusets, update_tasks_nodemask()
is called, which calls do_migrate_pages(xx, from, to). Then those
tasks are moved to an ancestor, and do_migrate_pages() is called
again.
The first time: from = node_to_be_offlined, to = empty.
The second time: from = empty, to = ancestor's nodemask.
so looks like no pages will be migrated.
Fix this by:
- Don't call update_tasks_nodemask() on empty cpusets.
- Pass cs->old_mems_allowed to do_migrate_pages().
v4: added comment in cpuset_hotplug_update_tasks() and rephased comment
in cpuset_attach().
Signed-off-by: Li Zefan <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
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Currently some cpuset behaviors are not friendly when cpuset is co-mounted
with other cgroup controllers.
Now with this patchset if cpuset is mounted with sane_behavior option,
it behaves differently:
- Tasks will be kept in empty cpusets when hotplug happens and take
masks of ancestors with non-empty cpus/mems, instead of being moved to
an ancestor.
- A task can be moved into an empty cpuset, and again it takes masks of
ancestors, so the user can drop a task into a newly created cgroup without
having to do anything for it.
As tasks can reside in empy cpusets, here're some rules:
- They can be moved to another cpuset, regardless it's empty or not.
- Though it takes masks from ancestors, it takes other configs from the
empty cpuset.
- If the ancestors' masks are changed, those tasks will also be updated
to take new masks.
v2: add documentation in include/linux/cgroup.h
Signed-off-by: Li Zefan <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
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To achieve this:
- We call update_tasks_cpumask/nodemask() for empty cpusets when
hotplug happens, instead of moving tasks out of them.
- When a cpuset's masks are changed by writing cpuset.cpus/mems,
we also update tasks in child cpusets which are empty.
v3:
- do propagation work in one place for both hotplug and unplug
v2:
- drop rcu_read_lock before calling update_task_nodemask() and
update_task_cpumask(), instead of using workqueue.
- add documentation in include/linux/cgroup.h
Signed-off-by: Li Zefan <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
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effective_cpumask_cpuset() returns an ancestor cpuset which has
non-empty cpumask.
If a cpuset is empty and the tasks in it need to update their
cpus_allowed, they take on the ancestor cpuset's cpumask.
This currently won't change any behavior, but it will later allow us
to keep tasks in empty cpusets.
Signed-off-by: Li Zefan <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
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When we update a cpuset's mems_allowed and thus update tasks'
mems_allowed, it's required to pass the old mems_allowed and new
mems_allowed to cpuset_migrate_mm().
Currently we save old mems_allowed in a temp local variable before
changing cpuset->mems_allowed. This patch changes it by saving
old mems_allowed in cpuset->old_mems_allowed.
This currently won't change any behavior, but it will later allow
us to keep tasks in empty cpusets.
v3: restored "cpuset_attach_nodemask_to = cs->mems_allowed"
Signed-off-by: Li Zefan <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
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Merge misc fixes from Andrew Morton:
"Bunch of fixes and one little addition to math64.h"
* emailed patches from Andrew Morton <[email protected]>: (27 commits)
include/linux/math64.h: add div64_ul()
mm: memcontrol: fix lockless reclaim hierarchy iterator
frontswap: fix incorrect zeroing and allocation size for frontswap_map
kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules()
mm: migration: add migrate_entry_wait_huge()
ocfs2: add missing lockres put in dlm_mig_lockres_handler
mm/page_alloc.c: fix watermark check in __zone_watermark_ok()
drivers/misc/sgi-gru/grufile.c: fix info leak in gru_get_config_info()
aio: fix io_destroy() regression by using call_rcu()
rtc-at91rm9200: use shadow IMR on at91sam9x5
rtc-at91rm9200: add shadow interrupt mask
rtc-at91rm9200: refactor interrupt-register handling
rtc-at91rm9200: add configuration support
rtc-at91rm9200: add match-table compile guard
fs/ocfs2/namei.c: remove unecessary ERROR when removing non-empty directory
swap: avoid read_swap_cache_async() race to deadlock while waiting on discard I/O completion
drivers/rtc/rtc-twl.c: fix missing device_init_wakeup() when booted with device tree
cciss: fix broken mutex usage in ioctl
audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE
drivers/rtc/rtc-cmos.c: fix accidentally enabling rtc channel
...
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audit_add_tree_rule() must set 'rule->tree = NULL;' firstly, to protect
the rule itself freed in kill_rules().
The reason is when it is killed, the 'rule' itself may have already
released, we should not access it. one example: we add a rule to an
inode, just at the same time the other task is deleting this inode.
The work flow for adding a rule:
audit_receive() -> (need audit_cmd_mutex lock)
audit_receive_skb() ->
audit_receive_msg() ->
audit_receive_filter() ->
audit_add_rule() ->
audit_add_tree_rule() -> (need audit_filter_mutex lock)
...
unlock audit_filter_mutex
get_tree()
...
iterate_mounts() -> (iterate all related inodes)
tag_mount() ->
tag_trunk() ->
create_trunk() -> (assume it is 1st rule)
fsnotify_add_mark() ->
fsnotify_add_inode_mark() -> (add mark to inode->i_fsnotify_marks)
...
get_tree(); (each inode will get one)
...
lock audit_filter_mutex
The work flow for deleting an inode:
__destroy_inode() ->
fsnotify_inode_delete() ->
__fsnotify_inode_delete() ->
fsnotify_clear_marks_by_inode() -> (get mark from inode->i_fsnotify_marks)
fsnotify_destroy_mark() ->
fsnotify_destroy_mark_locked() ->
audit_tree_freeing_mark() ->
evict_chunk() ->
...
tree->goner = 1
...
kill_rules() -> (assume current->audit_context == NULL)
call_rcu() -> (rule->tree != NULL)
audit_free_rule_rcu() ->
audit_free_rule()
...
audit_schedule_prune() -> (assume current->audit_context == NULL)
kthread_run() -> (need audit_cmd_mutex and audit_filter_mutex lock)
prune_one() -> (delete it from prue_list)
put_tree(); (match the original get_tree above)
Signed-off-by: Chen Gang <[email protected]>
Cc: Eric Paris <[email protected]>
Cc: Al Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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audit_log_start() does wait_for_auditd() in a loop until
audit_backlog_wait_time passes or audit_skb_queue has a room.
If signal_pending() is true this becomes a busy-wait loop, schedule() in
TASK_INTERRUPTIBLE won't block.
Thanks to Guy for fully investigating and explaining the problem.
(akpm: that'll cause the system to lock up on a non-preemptible
uniprocessor kernel)
(Guy: "Our customer was in fact running a uniprocessor machine, and they
reported a system hang.")
Signed-off-by: Oleg Nesterov <[email protected]>
Reported-by: Guy Streeter <[email protected]>
Cc: Eric Paris <[email protected]>
Cc: Al Viro <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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The dmesg_restrict sysctl currently covers the syslog method for access
dmesg, however /dev/kmsg isn't covered by the same protections. Most
people haven't noticed because util-linux dmesg(1) defaults to using the
syslog method for access in older versions. With util-linux dmesg(1)
defaults to reading directly from /dev/kmsg.
To fix /dev/kmsg, let's compare the existing interfaces and what they
allow:
- /proc/kmsg allows:
- open (SYSLOG_ACTION_OPEN) if CAP_SYSLOG since it uses a destructive
single-reader interface (SYSLOG_ACTION_READ).
- everything, after an open.
- syslog syscall allows:
- anything, if CAP_SYSLOG.
- SYSLOG_ACTION_READ_ALL and SYSLOG_ACTION_SIZE_BUFFER, if
dmesg_restrict==0.
- nothing else (EPERM).
The use-cases were:
- dmesg(1) needs to do non-destructive SYSLOG_ACTION_READ_ALLs.
- sysklog(1) needs to open /proc/kmsg, drop privs, and still issue the
destructive SYSLOG_ACTION_READs.
AIUI, dmesg(1) is moving to /dev/kmsg, and systemd-journald doesn't
clear the ring buffer.
Based on the comments in devkmsg_llseek, it sounds like actions besides
reading aren't going to be supported by /dev/kmsg (i.e.
SYSLOG_ACTION_CLEAR), so we have a strict subset of the non-destructive
syslog syscall actions.
To this end, move the check as Josh had done, but also rename the
constants to reflect their new uses (SYSLOG_FROM_CALL becomes
SYSLOG_FROM_READER, and SYSLOG_FROM_FILE becomes SYSLOG_FROM_PROC).
SYSLOG_FROM_READER allows non-destructive actions, and SYSLOG_FROM_PROC
allows destructive actions after a capabilities-constrained
SYSLOG_ACTION_OPEN check.
- /dev/kmsg allows:
- open if CAP_SYSLOG or dmesg_restrict==0
- reading/polling, after open
Addresses https://bugzilla.redhat.com/show_bug.cgi?id=903192
[[email protected]: use pr_warn_once()]
Signed-off-by: Kees Cook <[email protected]>
Reported-by: Christian Kujau <[email protected]>
Tested-by: Josh Boyer <[email protected]>
Cc: Kay Sievers <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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We recently noticed that reboot of a 1024 cpu machine takes approx 16
minutes of just stopping the cpus. The slowdown was tracked to commit
f96972f2dc63 ("kernel/sys.c: call disable_nonboot_cpus() in
kernel_restart()").
The current implementation does all the work of hot removing the cpus
before halting the system. We are switching to just migrating to the
boot cpu and then continuing with shutdown/reboot.
This also has the effect of not breaking x86's command line parameter
for specifying the reboot cpu. Note, this code was shamelessly copied
from arch/x86/kernel/reboot.c with bits removed pertaining to the
reboot_cpu command line parameter.
Signed-off-by: Robin Holt <[email protected]>
Tested-by: Shawn Guo <[email protected]>
Cc: "Srivatsa S. Bhat" <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Russ Anderson <[email protected]>
Cc: Robin Holt <[email protected]>
Cc: Russell King <[email protected]>
Cc: Guan Xuetao <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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There are instances in the kernel where we would like to disable CPU
hotplug (from sysfs) during some important operation. Today the freezer
code depends on this and the code to do it was kinda tailor-made for
that.
Restructure the code and make it generic enough to be useful for other
usecases too.
Signed-off-by: Srivatsa S. Bhat <[email protected]>
Signed-off-by: Robin Holt <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Russ Anderson <[email protected]>
Cc: Robin Holt <[email protected]>
Cc: Russell King <[email protected]>
Cc: Guan Xuetao <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Nothing about the sched_clock implementation in the ARM port is
specific to the architecture. Generalize the code so that other
architectures can use it by selecting GENERIC_SCHED_CLOCK.
Signed-off-by: Stephen Boyd <[email protected]>
[jstultz: Merge minor collisions with other patches in my tree]
Signed-off-by: John Stultz <[email protected]>
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Export symbols so they can be used by
drivers/staging/android/alarm-dev.c if it is built as a module.
So far alarm-dev is built-in but module support is planned (see
drivers/staging/android/TODO).
Signed-off-by: Marcus Gelderie <[email protected]>
[jstultz: tweaked commit message, also export newly added functions]
Signed-off-by: John Stultz <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"Yoshihiro Yunomae fixed a regression in the output format when using
one of the counter clocks.
The new multibuffer code changed the trace_clock file to update the
trace instances tr->clock_id but the actual traces still used the
value from the obsolete global variable trace_clock_id"
* tag 'trace-fixes-v3.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix outputting formats of x86-tsc and counter when use trace_clock
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There's no point calling it when _alloc() failed.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
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The function tracer uses preempt_disable/enable_notrace() for
synchronization between reading registered ftrace_ops and unregistering
them.
Most of the ftrace_ops are global permanent structures that do not
require this synchronization. That is, ops may be added and removed from
the hlist but are never freed, and wont hurt if a synchronization is
missed.
But this is not true for dynamically created ftrace_ops or control_ops,
which are used by the perf function tracing.
The problem here is that the function tracer can be used to trace
kernel/user context switches as well as going to and from idle.
Basically, it can be used to trace blind spots of the RCU subsystem.
This means that even though preempt_disable() is done, a
synchronize_sched() will ignore CPUs that haven't made it out of user
space or idle. These can include functions that are being traced just
before entering or exiting the kernel sections.
To implement the RCU synchronization, instead of using
synchronize_sched() the use of schedule_on_each_cpu() is performed. This
means that when a dynamically allocated ftrace_ops, or a control ops is
being unregistered, all CPUs must be touched and execute a ftrace_sync()
stub function via the work queues. This will rip CPUs out from idle or
in dynamic tick mode. This only happens when a user disables perf
function tracing or other dynamically allocated function tracers, but it
allows us to continue to debug RCU and context tracking with function
tracing.
Link: http://lkml.kernel.org/r/[email protected]
Cc: "Paul E. McKenney" <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Acked-by: Paul E. McKenney <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
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Commit 4f271a2a60c748599b30bb4dafff30d770439b96
(tracing: Add a proc file to stop tracing and free buffer)
implement a method to free up ring buffer in kernel memory
in the release code path of free_buffer's fd.
Then we don't need read/write support for free_buffer,
indeed we just have a dummy write fop, and don't implement read fop.
So the 0200 is more reasonable file mode for free_buffer than
the current file mode 0644.
Link: http://lkml.kernel.org/r/20130526085201.GA3183@udknight
Acked-by: Vaibhav Nagarnaik <[email protected]>
Acked-by: David Sharp <[email protected]>
Signed-off-by: Wang YanQing <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
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Consolidate the checks for !enabled and !param to return -EINVAL
in event_enable_func().
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Harsh Prateek Bora <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
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Add the "cpudump" command to have the current CPU ftrace buffer dumped
to console if a function is hit. This is useful when debugging a
tripple fault, where you have an idea of a function that is called
just before the tripple fault occurs, and can tell ftrace to dump its
content out to the console before it continues.
This differs from the "dump" command as it only dumps the content of
the ring buffer for the currently executing CPU, and does not show
the contents of the other CPUs.
Format is:
<function>:cpudump
echo 'bad_address:cpudump' > /debug/tracing/set_ftrace_filter
To remove this:
echo '!bad_address:cpudump' > /debug/tracing/set_ftrace_filter
Signed-off-by: Steven Rostedt <[email protected]>
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Add the "dump" command to have the ftrace buffer dumped to console if
a function is hit. This is useful when debugging a tripple fault,
where you have an idea of a function that is called just before the
tripple fault occurs, and can tell ftrace to dump its content out
to the console before it continues.
Format is:
<function>:dump
echo 'bad_address:dump' > /debug/tracing/set_ftrace_filter
To remove this:
echo '!bad_address:dump' > /debug/tracing/set_ftrace_filter
Requested-by: Luis Claudio R. Goncalves <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
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This adds in a new message to the wakeup code which adds an
indication to the log that suspend was cancelled due to a wake event
occouring during the suspend sequence. It also adjusts the message
printed in suspend.c to reflect the potential that a suspend was
aborted, as opposed to a device failing to suspend.
Without these message adjustments one can end up with a kernel log
that says that a device failed to suspend with no actual device
suspend failures, which can be confusing to the log examiner.
Signed-off-by: Bernie Thompson <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
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Moving x86 to the generic idle implementation (commit 7d1a9417 "x86:
Use generic idle loop") wreckaged the stack protector.
I stupidly missed that boot_init_stack_canary() must be inlined from a
function which never returns, but I put that call into
arch_cpu_idle_prepare() which of course returns.
I pondered to play tricks with arch_cpu_idle_prepare() first, but then
I noticed, that the other archs which have implemented the
stackprotector (ARM and SH) do not initialize the canary for the
non-boot cpus.
So I decided to move the boot_init_stack_canary() call into
cpu_startup_entry() ifdeffed with an CONFIG_X86 for now. This #ifdef
is just a temporary measure as I don't want to inflict the
boot_init_stack_canary() call on ARM and SH that late in the cycle.
I'll queue a patch for 3.11 which removes the #ifdef if the ARM/SH
maintainers have no objection.
Reported-by: Wouter van Kesteren <[email protected]>
Cc: [email protected]
Cc: Russell King <[email protected]>
Cc: Paul Mundt <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
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Outputting formats of x86-tsc and counter should be a raw format, but after
applying the patch(2b6080f28c7cc3efc8625ab71495aae89aeb63a0), the format was
changed to nanosec. This is because the global variable trace_clock_id was used.
When we use multiple buffers, clock_id of each sub-buffer should be used. Then,
this patch uses tr->clock_id instead of the global variable trace_clock_id.
[ Basically, this fixes a regression where the multibuffer code changed the
trace_clock file to update tr->clock_id but the traces still use the old
global trace_clock_id variable, negating the file's effect. The global
trace_clock_id variable is obsolete and removed. - SR ]
Link: http://lkml.kernel.org/r/20130423013239.22334.7394.stgit@yunodevel
Signed-off-by: Yoshihiro YUNOMAE <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
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When a threaded irq handler is installed the irq thread is initially
created on normal scheduling priority. Only after the irq thread is
woken up it sets its priority to RT_FIFO MAX_USER_RT_PRIO/2 itself.
This means that interrupts that occur directly after the irq handler
is installed will be handled on a normal scheduling priority instead
of the realtime priority that one would expect.
Fix this by setting the RT priority on creation of the irq_thread.
Signed-off-by: Ivo Sieben <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Steven Rostedt <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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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 <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Acked-by: Pekka Riikonen <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
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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 <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
[ paulmck: Updated to eliminate #else in rcutiny.h as suggested by Josh ]
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Lai Jiangshan <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
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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 <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
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