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We need the PID namespace and counter ID available when the
counter overflows and we need to generate a sample event.
[ Impact: fix kernel crash with high-frequency sampling ]
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
[ fixed a further crash and cleaned up the initialization a bit ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I noticed missing COMM events and found that we missed
reporting them for pure forks.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
On creating a new task while running the function graph tracer, if
we fail to allocate the ret_stack, and then fail the fork, the
code will free the parent ret_stack. This is because the child
duplicated the parent and currently points to the parent's ret_stack.
This patch always initializes the task's ret_stack to NULL.
[ Impact: prevent crash of parent on low memory during fork ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the function graph tracer is enabled, all new tasks must allocate
a ret_stack to place the return address of functions. This is because
the function graph tracer will replace the real return address with a
call to the tracing of the exit function.
This initialization happens in fork, but it happens too late. If fork
fails, then it will call free_task and that calls the freeing of this
ret_stack. But before initialization happens, the new (failed) task
points to its parents ret_stack. If a fork failure happens during
the function trace, it would be catastrophic for the parent.
Also, there's no need to call ftrace_graph_exit_task from fork, since
it is called by free_task which fork calls on failure.
[ Impact: prevent crash during failed fork running function graph tracer ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The structure isn't hw only and when I read event, I think about those
things that fall out the other end. Rename the thing.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
Cc: Stephane Eranian <eranian@googlemail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since some people worried that 4G might not be a large enough
as an mmap data window, extend it to 64 bit for capable
platforms.
Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A few renames:
s/irq_period/sample_period/
s/irq_freq/sample_freq/
s/PERF_RECORD_/PERF_SAMPLE_/
s/record_type/sample_type/
And change both the new sample_type and read_format to u64.
Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Stephan raised the issue that we currently cannot distinguish between
similar counters within a group (PERF_RECORD_GROUP uses the config
value as identifier).
Therefore, generate a new ID for each counter using a global u64
sequence counter.
Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The code that handles the tasks ret_stack allocation for every task
assumes that only an interrupt can cause issues (even though interrupts
are disabled).
In reality, the code is allocating the ret_stack for tasks that may be
running on other CPUs and there are not efficient memory barriers to
handle this case.
[ Impact: prevent crash due to using of uninitialized ret_stack variables ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The function graph tracer checks if the task_struct has ret_stack defined
to know if it is OK or not to use it. The initialization is done for
all tasks by one process, but the idle tasks use the same initialization
used by new tasks.
If an interrupt happens on an idle task that just had the ret_stack
created, but before the rest of the initialization took place, then
we can corrupt the return address of the functions.
This patch moves the setting of the task_struct's ret_stack to after
the other variables have been initialized.
[ Impact: prevent kernel panic on idle task when starting function graph ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the function graph tracer is enabled, it calls the initialization
needed for the init tasks that would be called on all created tasks.
The problem is that this is called every time the function graph tracer
is enabled, and the ret_stack is allocated for the idle tasks each time.
Thus, the old ret_stack is lost and a memory leak is created.
This is also dangerous because if an interrupt happened on another CPU
with the init task and the ret_stack is replaced, we then lose all the
return pointers for the interrupt, and a crash would take place.
[ Impact: fix memory leak and possible crash due to race ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Stop using task_struct::pid and start using PID namespaces.
PIDs will be reported in the PID namespace of the monitoring
task at the moment of counter creation.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This removes the prev_state field of struct perf_counter since
it is now unused. It was only used by the cpu migration
counter, which doesn't use it any more.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <18979.35052.915728.626374@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This fixes the cpu migration software counter to count
correctly even when contexts get swapped from one task to
another. Previously the cpu migration counts reported by perf
stat were bogus, ranging from negative to several thousand for
a single "lat_ctx 2 8 32" run. With this patch the cpu
migration count reported for "lat_ctx 2 8 32" is almost always
between 35 and 44.
This fixes the problem by adding a call into the perf_counter
code from set_task_cpu when tasks are migrated. This enables
us to use the generic swcounter code (with some modifications)
for the cpu migration counter.
This modifies the swcounter code to allow a NULL regs pointer
to be passed in to perf_swcounter_ctx_event() etc. The cpu
migration counter does this because there isn't necessarily a
pt_regs struct for the task available. In this case, the
counter will not have interrupt capability - but the migration
counter didn't have interrupt capability before, so this is no
loss.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <18979.35006.819769.416327@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This arranges for perf_counter's notifier for cpu hotplug
operations to be called earlier than the migration notifier in
sched.c by increasing its priority to 20, compared to the 10
for the migration notifier. The reason for doing this is that
a subsequent commit to convert the cpu migration counter to use
the generic swcounter infrastructure will add a call into the
perf_counter subsystem when tasks get migrated. Therefore the
perf_counter subsystem needs a chance to initialize its per-cpu
data for the new cpu before it can get called from the
migration code.
This also adds a comment to the migration notifier noting that
its priority needs to be lower than that of the perf_counter
notifier.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <18981.1900.792795.836858@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A race was found that if one were to enable and disable the function
profiler repeatedly, then the system can panic. This was because a profiled
function may be preempted just before disabling interrupts. While
the profiler is disabled and then reenabled, the preempted function
could start again, and access the hash as it is being initialized.
This just adds a check in the irq disabled part to check if the profiler
is enabled, and if it is not then it will just exit.
When the system is disabled, the profile_enabled variable is cleared
before calling the unregistering of the function profiler. This
unregistering calls stop machine which also acts as a synchronize schedule.
[ Impact: fix panic in enabling/disabling function profiler ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The trace_pipe did not recognize the latency format flag and would produce
different output than the trace file. The problem was partly due that
the trace flags in the iterator was not set as well as the trace_pipe
zeros out part of the iterator (including the flags) to be able to use
the same routines as the trace file. trace_flags of the iterator should
not cause any problems when not zeroed out by for trace_pipe.
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
A patch to allow the use of __print_symbolic and __print_flags
from a module. This allows the current GFS2 tracing patch to
build.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
LKML-Reference: <1243868015.29604.542.camel@localhost.localdomain>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
__string() is limited:
- it's a char array, but we may want to define array with other types
- a source string should be available, but we may just know the string size
We introduce __dynamic_array() to break those limitations, and __string()
becomes a wrapper of it. As a side effect, now __get_str() can be used
in TP_fast_assign but not only TP_print.
Take XFS for example, we have the string length in the dirent, but the
string itself is not NULL-terminated, so __dynamic_array() can be used:
TRACE_EVENT(xfs_dir2,
TP_PROTO(struct xfs_da_args *args),
TP_ARGS(args),
TP_STRUCT__entry(
__field(int, namelen)
__dynamic_array(char, name, args->namelen + 1)
...
),
TP_fast_assign(
char *name = __get_str(name);
if (args->namelen)
memcpy(name, args->name, args->namelen);
name[args->namelen] = '\0';
__entry->namelen = args->namelen;
),
TP_printk("name %.*s namelen %d",
__entry->namelen ? __get_str(name) : NULL
__entry->namelen)
);
[ Impact: allow defining dynamic size arrays ]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A2384D2.3080403@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Both event tracer and sched switch plugin are selected by default
by all generic tracers. But if no generic tracer is enabled, their options
appear. But ether one of them will select the other, thus it only
makes sense to have the default tracers be selected by one option.
[ Impact: clean up kconfig menu ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There are two options that are selected by all tracers, but we want
to have those options available when no tracer is selected. These are
The event tracer and sched switch tracer.
The are enabled by all tracers, but if a tracer is not selected we want
the options to appear. All tracers including them select TRACING.
Thus what we would like to do is:
config EVENT_TRACER
bool "prompt"
depends on TRACING
select TRACING
But that gives us a bug in the kbuild system since we just created a
circular dependency. We only want the prompt to show when TRACING is off.
This patch adds GENERIC_TRACER that all tracers will select instead of
TRACING. The two options (sched switch and event tracer) will select
TRACING directly and depend on !GENERIC_TRACER. This solves the cicular
dependency.
[ Impact: hide options that are selected by default ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When using ftrace=function on the command line to trace functions
on boot up, one can not filter out functions that are commonly called.
This patch adds two new ftrace command line commands.
ftrace_notrace=function-list
ftrace_filter=function-list
Where function-list is a comma separated list of functions to filter.
The ftrace_notrace will make the functions listed not be included
in the function tracing, and ftrace_filter will only trace the functions
listed.
These two act the same as the debugfs/tracing/set_ftrace_notrace and
debugfs/tracing/set_ftrace_filter respectively.
The simple glob expressions that are allowed by the filter files can also
be used by the command line interface.
ftrace_notrace=rcu*,*lock,*spin*
Will not trace any function that starts with rcu, ends with lock, or has
the word spin in it.
Note, if the self tests are enabled, they may interfere with the filtering
set by the command lines.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
register_stat_tracer() uses list_for_each_entry_safe
to check whether a tracer is already present in the list.
But we don't delete anything from the list here, so
we don't need the safe version
[ Impact: cleanup list use is stat tracing ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
- remove duplicate code in stat_seq_init()
- update comments to reflect the change from stat list to stat rbtree
[ Impact: clean up ]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
When closing a trace_stat file, we destroy the rbtree constructed during
file open, but there is memory leak that the root node is not freed.
[ Impact: fix memory leak when closing a trace_stat file ]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Currently the output of trace_stat/workqueues is totally reversed:
# cat /debug/tracing/trace_stat/workqueues
...
1 17 17 210 37 `-blk_unplug_work+0x0/0x57
1 3779 3779 181 11 |-cfq_kick_queue+0x0/0x2f
1 3796 3796 kblockd/1:120
...
The correct output should be:
1 3796 3796 kblockd/1:120
1 3779 3779 181 11 |-cfq_kick_queue+0x0/0x2f
1 17 17 210 37 `-blk_unplug_work+0x0/0x57
It's caused by "tracing/stat: replace linked list by an rbtree for
sorting"
(53059c9b67a62a3dc8c80204d3da42b9267ea5a0).
dummpy_cmp() should return -1, so rb_node will always be inserted as
right-most node in the rbtree, thus we sort the output in ascending
order.
[ Impact: fix the output of trace_stat/workqueues ]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
When the stat tracing framework prepares the entries from a tracer
to output them to the user, it starts by computing a linear sort
through a linked list to give the entries ordered by relevance
to the user.
This is quite ugly and causes a small latency when we begin to
read the file.
This patch changes that by turning the linked list into a red-black
tree. Athough the whole iteration using the start and next tracer
callbacks while opening the file remain the same, it is now much
more fast and scalable.
The rbtree guarantees O(log(n)) insertions whereas a linked
list with linear sorting brought us a O(n) despair. Now the
(visible) latency has disapeared.
[ Impact: kill the latency while starting to read a stat tracer file ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
The "trace" prefix in struct trace_stat_session type is annoying while
reading the trace_stat.c file. It makes the lines longer, and
is not that much useful to explain the sense of this type.
Just keep "struct stat_session" for this type.
[ Impact: make the code a bit more readable ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
The blankline between each cpu's workqueue stat is not necessary, because
the cpu number is enough to part them by eye.
Old style also caused a blankline below headline, and made code complex
by using lock, disableirq and get cpu var.
Old style:
# CPU INSERTED EXECUTED NAME
# | | | |
0 8644 8644 events/0
0 0 0 cpuset
...
0 1 1 kdmflush
1 35365 35365 events/1
...
New style:
# CPU INSERTED EXECUTED NAME
# | | | |
0 8644 8644 events/0
0 0 0 cpuset
...
0 1 1 kdmflush
1 35365 35365 events/1
...
[ Impact: provide more readable code ]
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
cpu_workqueue_stats->first_entry is useless because we can retrieve the
header of a cpu workqueue using:
if (&cpu_workqueue_stats->list == workqueue_cpu_stat(cpu)->list.next)
[ Impact: cleanup ]
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
No need to use list_for_each_entry_safe() in iteration without deleting
any node, we can use list_for_each_entry() instead.
[ Impact: cleanup ]
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
v3: zhaolei@cn.fujitsu.com: Change TRACE_EVENT definition to new format
introduced by Steven Rostedt: consolidate trace and trace_event headers
v2: kosaki@jp.fujitsu.com: print the function names instead of addr, and zap
the work addr
v1: zhaolei@cn.fujitsu.com: Make workqueue tracepoints use TRACE_EVENT macro
TRACE_EVENT is a more generic way to define tracepoints.
Doing so adds these new capabilities to the tracepoints:
- zero-copy and per-cpu splice() tracing
- binary tracing without printf overhead
- structured logging records exposed under /debug/tracing/events
- trace events embedded in function tracer output and other plugins
- user-defined, per tracepoint filter expressions
Then, this patch converts DEFINE_TRACE to TRACE_EVENT in workqueue related
tracepoints.
[ Impact: expand workqueue tracer to events tracing ]
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Merge reason: arch/x86/kernel/irqinit_{32,64}.c unified in irq/numa
and modified in x86/mce3; this merge resolves the conflict.
Conflicts:
arch/x86/kernel/irqinit.c
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Conflicts:
arch/mips/sibyte/bcm1480/irq.c
arch/mips/sibyte/sb1250/irq.c
Merge reason: we gathered a few conflicts plus update to latest upstream fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This changes perf_swcounter_match() so that per-task software
counters can count events that occur while their associated
task is not running. This will allow us to use the generic
software counter code for counting task migrations, which can
occur while the task is not scheduled in.
To do this, we have to distinguish between the situations where
the counter is inactive because its task has been scheduled
out, and those where the counter is inactive because it is part
of a group that was not able to go on the PMU. In the former
case we want the counter to count, but not in the latter case.
If the context is active, we have the latter case. If the
context is inactive then we need to know whether the counter
was counting when the context was last active, which we can
determine by comparing its ->tstamp_stopped timestamp with the
context's timestamp.
This also folds three checks in perf_swcounter_match, checking
perf_event_raw(), perf_event_type() and perf_event_id()
individually, into a single 64-bit comparison on
counter->hw_event.config, as an optimization.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <18979.34810.259718.955621@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This abstracts out the code for locking the context associated
with a task. Because the context might get transferred from
one task to another concurrently, we have to check after
locking the context that it is still the right context for the
task and retry if not. This was open-coded in
find_get_context() and perf_counter_init_task().
This adds a further function for pinning the context for a
task, i.e. marking it so it can't be transferred to another
task. This adds a 'pin_count' field to struct
perf_counter_context to indicate that a context is pinned,
instead of the previous method of setting the parent_gen count
to all 1s. Pinning the context with a pin_count is easier to
undo and doesn't require saving the parent_gen value. This
also adds a perf_unpin_context() to undo the effect of
perf_pin_task_context() and changes perf_counter_init_task to
use it.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <18979.34748.755674.596386@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Merge reason: merge almost-rc8 into perfcounters/core, which was -rc6
based - to pick up the latest upstream fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When fork() fails we cannot use perf_counter_exit_task() since that
assumes to operate on current. Write a new helper that cleans up
unused/clean contexts.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Remove the local_irq_save() etc.. in routines that are smp function
calls, or have IRQs disabled by other means.
Then change the COMM, MMAP, and swcounter context iteration to
current->perf_counter_ctxp and RCU, since it really doesn't matter
which context they iterate, they're all folded.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Commit a63eaf34ae6 ("perf_counter: Dynamically allocate tasks'
perf_counter_context struct") broke COMM and MMAP notification for
cpu wide counters by dropping out early if there was no task context,
thereby also not iterating the cpu context.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This fixes a nasty crash and highlights a bug that we were
freeing failed-fork() counters incorrectly.
(the fix for that will come separately)
[ Impact: fix crashes/lockups with inherited counters ]
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Peter noticed that we are sometimes reading cpuctx->task_ctx with
interrupts enabled.
Noticed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Peter Zijlstra pointed out that under some circumstances, we can take
the mutex in a context or a counter and then swap that context or
counter to another task, potentially leading to lock order inversions
or the mutexes not protecting what they are supposed to protect.
This fixes the problem by making sure that we never take a mutex in a
context or counter which could get swapped to another task. Most of
the cases where we take a mutex is on a top-level counter or context,
i.e. a counter which has an fd associated with it or a context that
contains such a counter. This adds WARN_ON_ONCE statements to verify
that.
The two cases where we need to take the mutex on a context that is a
clone of another are in perf_counter_exit_task and
perf_counter_init_task. The perf_counter_exit_task case is solved by
uncloning the context before starting to remove the counters from it.
The perf_counter_init_task is a little trickier; we temporarily
disable context swapping for the parent (forking) task by setting its
ctx->parent_gen to the all-1s value after locking the context, if it
is a cloned context, and restore the ctx->parent_gen value at the end
if the context didn't get uncloned in the meantime.
This also moves the increment of the context generation count to be
within the same critical section, protected by the context mutex, that
adds the new counter to the context. That way, taking the mutex is
sufficient to ensure that both the counter list and the generation
count are stable.
[ Impact: fix hangs, races with inherited and PID counters ]
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <18975.31580.520676.619896@drongo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Needed in followon patch.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Commit 564c2b21 ("perf_counter: Optimize context switch between
identical inherited contexts") introduced a race where it is possible
that a counter being attached to a task could get attached to the
wrong task, if the task is one that has inherited its context from
another task via fork. This happens because the optimized context
switch could switch the context to another task after find_get_context
has read task->perf_counter_ctxp. In fact, it's possible that the
context could then get freed, if the other task then exits.
This fixes the problem by protecting both the context switch and the
critical code in find_get_context with spinlocks. The context switch
locks the cxt->lock of both the outgoing and incoming contexts before
swapping them. That means that once code such as find_get_context
has obtained the spinlock for the context associated with a task,
the context can't get swapped to another task. However, the context
may have been swapped in the interval between reading
task->perf_counter_ctxp and getting the lock, so it is necessary to
check and retry.
To make sure that none of the contexts being looked at in
find_get_context can get freed, this changes the context freeing code
to use RCU. Thus an rcu_read_lock() is sufficient to ensure that no
contexts can get freed. This part of the patch is lifted from a patch
posted by Peter Zijlstra.
This also adds a check to make sure that we can't add a counter to a
task that is exiting.
There is also a race between perf_counter_exit_task and
find_get_context; this solves the race by moving the get_ctx that
was in perf_counter_alloc into the locked region in find_get_context,
so that once find_get_context has got the context for a task, it
won't get freed even if the task calls perf_counter_exit_task. It
doesn't matter if new top-level (non-inherited) counters get attached
to the context after perf_counter_exit_task has detached the context
from the task. They will just stay there and never get scheduled in
until the counters' fds get closed, and then perf_release will remove
them from the context and eventually free the context.
With this, we are now doing the unclone in find_get_context rather
than when a counter was added to or removed from a context (actually,
we were missing the unclone_ctx() call when adding a counter to a
context). We don't need to unclone when removing a counter from a
context because we have no way to remove a counter from a cloned
context.
This also takes out the smp_wmb() in find_get_context, which Peter
Zijlstra pointed out was unnecessary because the cmpxchg implies a
full barrier anyway.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <18974.33033.667187.273886@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A call from irq_exit() may occasionally pause the timing
info for cpufreq ondemand governor. This results in the
cpufreq ondemand governor to fail to calculate the
system load properly. Thus, relocate the checks for this
particular case to keep the governor always functional.
Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com>
Reported-by: Tero Kristo <tero.kristo@nokia.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
