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git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU updates from Paul E. McKenney:
1. Changes to rcutorture and to RCU documentation. Posted to LKML at
https://lkml.org/lkml/2013/1/26/188.
2. Enhancements to uniprocessor handling in tiny RCU. Posted to LKML
at https://lkml.org/lkml/2013/1/27/2.
3. Tag RCU callbacks with grace-period number to simplify callback
advancement. Posted to LKML at https://lkml.org/lkml/2013/1/26/203.
4. Miscellaneous fixes. Posted to LKML at https://lkml.org/lkml/2013/1/26/204.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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On early boot up, when the ftrace ring buffer is initialized, the
static variable current_trace is initialized to &nop_trace.
Before this initialization, current_trace is NULL and will never
become NULL again. It is always reassigned to a ftrace tracer.
Several places check if current_trace is NULL before it uses
it, and this check is frivolous, because at the point in time
when the checks are made the only way current_trace could be
NULL is if ftrace failed its allocations at boot up, and the
paths to these locations would probably not be possible.
By initializing current_trace to &nop_trace where it is declared,
current_trace will never be NULL, and we can remove all these
checks of current_trace being NULL which never needed to be
checked in the first place.
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Ftrace has a snapshot feature available from kernel space and
latency tracers (e.g. irqsoff) are using it. This patch enables
user applictions to take a snapshot via debugfs.
Add "snapshot" debugfs file in "tracing" directory.
snapshot:
This is used to take a snapshot and to read the output of the
snapshot.
# echo 1 > snapshot
This will allocate the spare buffer for snapshot (if it is
not allocated), and take a snapshot.
# cat snapshot
This will show contents of the snapshot.
# echo 0 > snapshot
This will free the snapshot if it is allocated.
Any other positive values will clear the snapshot contents if
the snapshot is allocated, or return EINVAL if it is not allocated.
Link: http://lkml.kernel.org/r/20121226025300.3252.86850.stgit@liselsia
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: David Sharp <dhsharp@google.com>
Signed-off-by: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
[
Fixed irqsoff selftest and also a conflict with a change
that fixes the update_max_tr.
]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Currently the trace buffer read functions use a static variable
"old_tracer" for detecting if the current tracer changes. This
was suitable for a single trace file ("trace"), but to add a
snapshot feature that will use the same function for its file,
a check against a static variable is not sufficient.
To use the output functions for two different files, instead of
storing the current tracer in a static variable, as the trace
iterator descriptor contains a pointer to the original current
tracer's name, that pointer can now be used to check if the
current tracer has changed between different reads of the trace
file.
Link: http://lkml.kernel.org/r/20121226025252.3252.9276.stgit@liselsia
Signed-off-by: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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For systems with an unstable sched_clock, all cpu_clock() does is enable/
disable local irq during the call to sched_clock_cpu(). And for stable
systems they are same.
trace_clock_global() already disables interrupts, so it can call
sched_clock_cpu() directly.
Link: http://lkml.kernel.org/r/1356576585-28782-2-git-send-email-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Add a stat about the number of events read from the ring buffer:
# cat /debug/tracing/per_cpu/cpu0/stats
entries: 39869
overrun: 870512
commit overrun: 0
bytes: 1449912
oldest event ts: 6561.368690
now ts: 6565.246426
dropped events: 0
read events: 112 <-- Added
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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While debugging the virtual cputime with the function graph tracer
with a max_depth of 1 (most common use of the max_depth so far),
I found that I was missing kernel execution because of a race condition.
The code for the return side of the function has a slight race:
ftrace_pop_return_trace(&trace, &ret, frame_pointer);
trace.rettime = trace_clock_local();
ftrace_graph_return(&trace);
barrier();
current->curr_ret_stack--;
The ftrace_pop_return_trace() initializes the trace structure for
the callback. The ftrace_graph_return() uses the trace structure
for its own use as that structure is on the stack and is local
to this function. Then the curr_ret_stack is decremented which
is what the trace.depth is set to.
If an interrupt comes in after the ftrace_graph_return() but
before the curr_ret_stack, then the called function will get
a depth of 2. If max_depth is set to 1 this function will be
ignored.
The problem is that the trace has already been called, and the
timestamp for that trace will not reflect the time the function
was about to re-enter userspace. Calls to the interrupt will not
be traced because the max_depth has prevented this.
To solve this issue, the ftrace_graph_return() can safely be
moved after the current->curr_ret_stack has been updated.
This way the timestamp for the return callback will reflect
the actual time.
If an interrupt comes in after the curr_ret_stack update and
ftrace_graph_return(), it will be traced. It may look a little
confusing to see it within the other function, but at least
it will not be lost.
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The trace iterator is already initialized by trace_init_global_iter(),
so there is no need to initialize it again.
Link: http://lkml.kernel.org/r/CACV3sb+G1YnO6168JhY3dEadmJi58pA5-2cSZT8E0WVHJNFt9Q@mail.gmail.com
Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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__this_cpu_inc_return() or __this_cpu_dec generates a single instruction,
which is faster than __get_cpu_var operation.
Link: http://lkml.kernel.org/r/50A9C1BD.1060308@gmail.com
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Shan Wei <davidshan@tencent.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The text in Documentation said it would be removed in 2.6.41;
the text in the Kconfig said removal in the 3.1 release. Either
way you look at it, we are well past both, so push it off a cliff.
Note that the POWER_CSTATE and the POWER_PSTATE are part of the
legacy tracing API. Remove all tracepoints which use these flags.
As can be seen from context, most already have a trace entry via
trace_cpu_idle anyways.
Also, the cpufreq/cpufreq.c PSTATE one is actually unpaired, as
compared to the CSTATE ones which all have a clear start/stop.
As part of this, the trace_power_frequency also becomes orphaned,
so it too is deleted.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Nothing outside of kernel/trace/trace.c references tracing_dentry_percpu().
Link: http://lkml.kernel.org/r/1353302917-13995-7-git-send-email-josh@joshtriplett.org
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Dan's smatch found a compare bug with the result of the
trace_test_and_set_recursion() and comparing to less than
zero. If the function fails, it returns -1, but was saved in
an unsigned int, which will never be less than zero and will
ignore the result of the test if a recursion did happen.
Luckily this is the last of the recursion tests, as the
infrastructure of ftrace would catch recursions before it
got here, except for some few exceptions.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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ring_buffer.c use to require declarations from trace.h, but
these have moved to the generic header files. There's nothing
in trace.h that ring_buffer.c requires.
There's some headers that trace.h included that ring_buffer.c
needs, but it's best that it includes them directly, and not
include trace.h.
Also, some things may use ring_buffer.c without having tracing
configured. This removes the dependency that may come in the
future.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Using context bit recursion checking, we can help increase the
performance of the ring buffer.
Before this patch:
# echo function > /debug/tracing/current_tracer
# for i in `seq 10`; do ./hackbench 50; done
Time: 10.285
Time: 10.407
Time: 10.243
Time: 10.372
Time: 10.380
Time: 10.198
Time: 10.272
Time: 10.354
Time: 10.248
Time: 10.253
(average: 10.3012)
Now we have:
# echo function > /debug/tracing/current_tracer
# for i in `seq 10`; do ./hackbench 50; done
Time: 9.712
Time: 9.824
Time: 9.861
Time: 9.827
Time: 9.962
Time: 9.905
Time: 9.886
Time: 10.088
Time: 9.861
Time: 9.834
(average: 9.876)
a 4% savings!
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The function tracer had two different versions of function tracing.
The disabling of irqs version and the preempt disable version.
As function tracing in very intrusive and can cause nasty recursion
issues, it has its own recursion protection. But the old method to
do this was a flat layer. If it detected that a recursion was happening
then it would just return without recording.
This made the preempt version (much faster than the irq disabling one)
not very useful, because if an interrupt were to occur after the
recursion flag was set, the interrupt would not be traced at all,
because every function that was traced would think it recursed on
itself (due to the context it preempted setting the recursive flag).
Now that we have a recursion flag for every context level, we
no longer need to worry about that. We can disable preemption,
set the current context recursion check bit, and go on. If an
interrupt were to come along, it would check its own context bit
and happily continue to trace.
As the preempt version is faster than the irq disable version,
there's no more reason to keep the preempt version around.
And the irq disable version still had an issue with missing
out on tracing NMI code.
Remove the irq disable function tracer version and have the
preempt disable version be the default (and only version).
Before this patch we had from running:
# echo function > /debug/tracing/current_tracer
# for i in `seq 10`; do ./hackbench 50; done
Time: 12.028
Time: 11.945
Time: 11.925
Time: 11.964
Time: 12.002
Time: 11.910
Time: 11.944
Time: 11.929
Time: 11.941
Time: 11.924
(average: 11.9512)
Now we have:
# echo function > /debug/tracing/current_tracer
# for i in `seq 10`; do ./hackbench 50; done
Time: 10.285
Time: 10.407
Time: 10.243
Time: 10.372
Time: 10.380
Time: 10.198
Time: 10.272
Time: 10.354
Time: 10.248
Time: 10.253
(average: 10.3012)
a 13.8% savings!
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When function tracing occurs, the following steps are made:
If arch does not support a ftrace feature:
call internal function (uses INTERNAL bits) which calls...
If callback is registered to the "global" list, the list
function is called and recursion checks the GLOBAL bits.
then this function calls...
The function callback, which can use the FTRACE bits to
check for recursion.
Now if the arch does not suppport a feature, and it calls
the global list function which calls the ftrace callback
all three of these steps will do a recursion protection.
There's no reason to do one if the previous caller already
did. The recursion that we are protecting against will
go through the same steps again.
To prevent the multiple recursion checks, if a recursion
bit is set that is higher than the MAX bit of the current
check, then we know that the check was made by the previous
caller, and we can skip the current check.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Convert the bits into enums which makes the code a little easier
to maintain.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Currently for recursion checking in the function tracer, ftrace
tests a task_struct bit to determine if the function tracer had
recursed or not. If it has, then it will will return without going
further.
But this leads to races. If an interrupt came in after the bit
was set, the functions being traced would see that bit set and
think that the function tracer recursed on itself, and would return.
Instead add a bit for each context (normal, softirq, irq and nmi).
A check of which context the task is in is made before testing the
associated bit. Now if an interrupt preempts the function tracer
after the previous context has been set, the interrupt functions
can still be traced.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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There is lots of places that perform:
op = rcu_dereference_raw(ftrace_control_list);
while (op != &ftrace_list_end) {
Add a helper macro to do this, and also optimize for a single
entity. That is, gcc will optimize a loop for either no iterations
or more than one iteration. But usually only a single callback
is registered to the function tracer, thus the optimized case
should be a single pass. to do this we now do:
op = rcu_dereference_raw(list);
do {
[...]
} while (likely(op = rcu_dereference_raw((op)->next)) &&
unlikely((op) != &ftrace_list_end));
An op is always registered (ftrace_list_end when no callbacks is
registered), thus when a single callback is registered, the link
list looks like:
top => callback => ftrace_list_end => NULL.
The likely(op = op->next) still must be performed due to the race
of removing the callback, where the first op assignment could
equal ftrace_list_end. In that case, the op->next would be NULL.
But this is unlikely (only happens in a race condition when
removing the callback).
But it is very likely that the next op would be ftrace_list_end,
unless more than one callback has been registered. This tells
gcc what the most common case is and makes the fast path with
the least amount of branches.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The function tracing recursion self test should not crash
the machine if the resursion test fails. If it detects that
the function tracing is recursing when it should not be, then
bail, don't go into an infinite recursive loop.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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If one of the function tracers set by the global ops is not recursion
safe, it can still be called directly without the added recursion
supplied by the ftrace infrastructure.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The test that checks function recursion does things differently
if the arch does not support all ftrace features. But that really
doesn't make a difference with how the test runs, and either way
the count variable should be 2 at the end.
Currently the test wrongly fails for archs that don't support all
the ftrace features.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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There's a race condition between the setting of a new tracer and
the update of the max trace buffers (the swap). When a new tracer
is added, it sets current_trace to nop_trace before disabling
the old tracer. At this moment, if the old tracer uses update_max_tr(),
the update may trigger the warning against !current_trace->use_max-tr,
as nop_trace doesn't have that set.
As update_max_tr() requires that interrupts be disabled, we can
add a check to see if current_trace == nop_trace and bail if it
does. Then when disabling the current_trace, set it to nop_trace
and run synchronize_sched(). This will make sure all calls to
update_max_tr() have completed (it was called with interrupts disabled).
As a clean up, this commit also removes shrinking and recreating
the max_tr buffer if the old and new tracers both have use_max_tr set.
The old way use to always shrink the buffer, and then expand it
for the next tracer. This is a waste of time.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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As trace_clock is used by other things besides tracing, and it
does not require anything from trace.h, it is best not to include
the header file in trace_clock.c.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Due to a userspace issue with PowerTop v2beta, which hardcoded
the offset of event fields that it was using, it broke when
we removed the Big Kernel Lock counter from the event header.
(commit e6e1e2593 "tracing: Remove lock_depth from event entry")
Because this broke userspace, it was determined that we must
keep those 4 bytes around.
(commit a3a4a5acd "Regression: partial revert "tracing: Remove lock_depth from event entry"")
This unfortunately wastes space in the ring buffer. 4 bytes per
event, where a lot of events are just 24 bytes. That's 16% of the
buffer wasted. A million events will add 4 megs of white space
into the buffer.
It was later noticed that PowerTop v2beta could not work on systems
where the kernel was 64 bit but the userspace was 32 bits.
The reason was because the offsets are different between the
two and the hard coded offset of one would not work with the other.
With PowerTop v2 final, it implemented the same interface that both
perf and trace-cmd use. That is, it reads the format file of
the event to find the offsets of the fields it needs. This fixes
the problem with running powertop on a 32 bit userspace running
on a 64 bit kernel. It also no longer requires the 4 byte padding.
As PowerTop v2 has been out for a while, and is included in all
major distributions, it is time that we can safely remove the
4 bytes of padding. Users of PowerTop v2beta should upgrade to
PowerTop v2 final.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Move SAVE_REGS support flag into Kconfig and rename
it to CONFIG_DYNAMIC_FTRACE_WITH_REGS. This also introduces
CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS which indicates
the architecture depending part of ftrace has a code
that saves full registers.
On the other hand, CONFIG_DYNAMIC_FTRACE_WITH_REGS indicates
the code is enabled.
Link: http://lkml.kernel.org/r/20120928081516.3560.72534.stgit@ltc138.sdl.hitachi.co.jp
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Add the file max_graph_depth to the debug tracing directory that lets
the user define the depth of the function graph.
A very useful operation is to set the depth to 1. Then it traces only
the first function that is called when entering the kernel. This can
be used to determine what system operations interrupt a process.
For example, to work on NOHZ processes (single tasks running without
a timer tick), if any interrupt goes off and preempts that task, this
code will show it happening.
# cd /sys/kernel/debug/tracing
# echo 1 > max_graph_depth
# echo function_graph > current_tracer
# cat per_cpu/cpu/<cpu-of-process>/trace
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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There's now a check in tracing_reset_online_cpus() if the buffer is
allocated or NULL. No need to do a check before calling it with max_tr.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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max_tr->buffer could be NULL in the tracing_reset{_online_cpus}. In this
case, a NULL pointer dereference happens, so we should return immediately
from these functions.
Note, the current code does not call tracing_reset*() with max_tr when
its buffer is NULL, but future code will. This patch is needed to prevent
the future code from crashing.
Link: http://lkml.kernel.org/r/20121219070234.31200.93863.stgit@liselsia
Signed-off-by: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Some functions in the syscall tracing is used only locally to
the file, but they are labeled global. Convert them to static functions.
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Without this patch, we can register a uprobe event for a directory.
Enabling such a uprobe event would anyway fail.
Example:
$ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events
However dirctories cannot be valid targets for uprobe.
Hence verify if the target is a regular file during the probe
registration.
Link: http://lkml.kernel.org/r/20130103004212.690763002@goodmis.org
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
[ cleaned up whitespace and removed redundant IS_DIR() check ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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typeof(&buffer) is a pointer to array of 1024 char, or char (*)[1024].
But, typeof(&buffer[0]) is a pointer to char which match the return type of get_trace_buf().
As well-known, the value of &buffer is equal to &buffer[0].
so return this_cpu_ptr(&percpu_buffer->buffer[0]) can avoid type cast.
Link: http://lkml.kernel.org/r/50A1A800.3020102@gmail.com
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Shan Wei <davidshan@tencent.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The original ring-buffer code had special checks at the start
of rb_advance_iter() and instead of repeating them again at the
end of the function if a certain condition existed, I just did
a recursive call to rb_advance_iter() because the special condition
would cause rb_advance_iter() to return early (after the checks).
But as things have changed, the special checks no longer exist
and the only thing done for the special_condition is to call
rb_inc_iter() and return. Instead of doing a confusing recursive call,
just call rb_inc_iter instead.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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If some other kernel subsystem has a module notifier, and adds a kprobe
to a ftrace mcount point (now that kprobes work on ftrace points),
when the ftrace notifier runs it will fail and disable ftrace, as well
as kprobes that are attached to ftrace points.
Here's the error:
WARNING: at kernel/trace/ftrace.c:1618 ftrace_bug+0x239/0x280()
Hardware name: Bochs
Modules linked in: fat(+) stap_56d28a51b3fe546293ca0700b10bcb29__8059(F) nfsv4 auth_rpcgss nfs dns_resolver fscache xt_nat iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack lockd sunrpc ppdev parport_pc parport microcode virtio_net i2c_piix4 drm_kms_helper ttm drm i2c_core [last unloaded: bid_shared]
Pid: 8068, comm: modprobe Tainted: GF 3.7.0-0.rc8.git0.1.fc19.x86_64 #1
Call Trace:
[<ffffffff8105e70f>] warn_slowpath_common+0x7f/0xc0
[<ffffffff81134106>] ? __probe_kernel_read+0x46/0x70
[<ffffffffa0180000>] ? 0xffffffffa017ffff
[<ffffffffa0180000>] ? 0xffffffffa017ffff
[<ffffffff8105e76a>] warn_slowpath_null+0x1a/0x20
[<ffffffff810fd189>] ftrace_bug+0x239/0x280
[<ffffffff810fd626>] ftrace_process_locs+0x376/0x520
[<ffffffff810fefb7>] ftrace_module_notify+0x47/0x50
[<ffffffff8163912d>] notifier_call_chain+0x4d/0x70
[<ffffffff810882f8>] __blocking_notifier_call_chain+0x58/0x80
[<ffffffff81088336>] blocking_notifier_call_chain+0x16/0x20
[<ffffffff810c2a23>] sys_init_module+0x73/0x220
[<ffffffff8163d719>] system_call_fastpath+0x16/0x1b
---[ end trace 9ef46351e53bbf80 ]---
ftrace failed to modify [<ffffffffa0180000>] init_once+0x0/0x20 [fat]
actual: cc:bb:d2:4b:e1
A kprobe was added to the init_once() function in the fat module on load.
But this happened before ftrace could have touched the code. As ftrace
didn't run yet, the kprobe system had no idea it was a ftrace point and
simply added a breakpoint to the code (0xcc in the cc:bb:d2:4b:e1).
Then when ftrace went to modify the location from a call to mcount/fentry
into a nop, it didn't see a call op, but instead it saw the breakpoint op
and not knowing what to do with it, ftrace shut itself down.
The solution is to simply give the ftrace module notifier the max priority.
This should have been done regardless, as the core code ftrace modification
also happens very early on in boot up. This makes the module modification
closer to core modification.
Link: http://lkml.kernel.org/r/20130107140333.593683061@goodmis.org
Cc: stable@vger.kernel.org
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reported-by: Frank Ch. Eigler <fche@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Commit 0fb9656d "tracing: Make tracing_enabled be equal to tracing_on"
changes the behaviour of trace_pipe, ie. it makes trace_pipe return if
we've read something and tracing is enabled, and this means that we have
to 'cat trace_pipe' again and again while running tests.
IMO the right way is if tracing is enabled, we always block and wait for
ring buffer, or we may lose what we want since ring buffer's size is limited.
Link: http://lkml.kernel.org/r/1358132051-5410-1-git-send-email-bo.li.liu@oracle.com
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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bio_{front|back}_merge tracepoints report a bio merging into an
existing request but didn't specify which request the bio is being
merged into. Add @req to it. This makes it impossible to share the
event template with block_bio_queue - split it out.
@req isn't used or exported to userland at this point and there is no
userland visible behavior change. Later changes will make use of the
extra parameter.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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bio completion didn't kick block_bio_complete TP. Only dm was
explicitly triggering the TP on IO completion. This makes
block_bio_complete TP useless for tracers which want to know about
bios, and all other bio based drivers skip generating blktrace
completion events.
This patch makes all bio completions via bio_endio() generate
block_bio_complete TP.
* Explicit trace_block_bio_complete() invocation removed from dm and
the trace point is unexported.
* @rq dropped from trace_block_bio_complete(). bios may fly around
w/o queue associated. Verifying and accessing the assocaited queue
belongs to TP probes.
* blktrace now gets both request and bio completions. Make it ignore
bio completions if request completion path is happening.
This makes all bio based drivers generate blktrace completion events
properly and makes the block_bio_complete TP actually useful.
v2: With this change, block_bio_complete TP could be invoked on sg
commands which have bio's with %NULL bi_bdev. Update TP
assignment code to check whether bio->bi_bdev is %NULL before
dereferencing.
Signed-off-by: Tejun Heo <tj@kernel.org>
Original-patch-by: Namhyung Kim <namhyung@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Commit 02404baf1b47 "tracing: Remove deprecated tracing_enabled file"
removed the tracing_enabled file as it never worked properly and
the tracing_on file should be used instead. But the tracing_on file
didn't call into the tracers start/stop routines like the
tracing_enabled file did. This caused trace-cmd to break when it
enabled the irqsoff tracer.
If you just did "echo irqsoff > current_tracer" then it would work
properly. But the tool trace-cmd disables tracing first by writing
"0" into the tracing_on file. Then it writes "irqsoff" into
current_tracer and then writes "1" into tracing_on. Unfortunately,
the above commit changed the irqsoff tracer to check the tracing_on
status instead of the tracing_enabled status. If it's disabled then
it does not start the tracer internals.
The problem is that writing "1" into tracing_on does not call the
tracers "start" routine like writing "1" into tracing_enabled did.
This makes the irqsoff tracer not start when using the trace-cmd
tool, and is a regression for userspace.
Simple fix is to have the tracing_on file call the tracers start()
method when being enabled (and the stop() method when disabled).
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The latest change to allow trace options to be set on the command
line also broke the trace_options file.
The zeroing of the last byte of the option name that is echoed into
the trace_option file was removed with the consolidation of some
of the code. The compare between the option and what was written to
the trace_options file fails because the string holding the data
written doesn't terminate with a null character.
A zero needs to be added to the end of the string copied from
user space.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The rcutorture tests need to be able to trace the time of the
beginning of an RCU read-side critical section, and thus need access
to trace_clock_local(). This commit therefore adds a the needed
EXPORT_SYMBOL_GPL().
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull minor tracing updates and fixes from Steven Rostedt:
"It seems that one of my old pull requests have slipped through.
The changes are contained to just the files that I maintain, and are
changes from others that I told I would get into this merge window.
They have already been in linux-next for several weeks, and should be
well tested."
* 'tip/perf/core-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Remove unnecessary WARN_ONCE's from tracing_buffers_splice_read
tracing: Remove unneeded checks from the stack tracer
tracing: Add a resize function to make one buffer equivalent to another buffer
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Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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But the kernel decided to call it "origin" instead. Fix most of the
sites.
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
Pull trivial branch from Jiri Kosina:
"Usual stuff -- comment/printk typo fixes, documentation updates, dead
code elimination."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (39 commits)
HOWTO: fix double words typo
x86 mtrr: fix comment typo in mtrr_bp_init
propagate name change to comments in kernel source
doc: Update the name of profiling based on sysfs
treewide: Fix typos in various drivers
treewide: Fix typos in various Kconfig
wireless: mwifiex: Fix typo in wireless/mwifiex driver
messages: i2o: Fix typo in messages/i2o
scripts/kernel-doc: check that non-void fcts describe their return value
Kernel-doc: Convention: Use a "Return" section to describe return values
radeon: Fix typo and copy/paste error in comments
doc: Remove unnecessary declarations from Documentation/accounting/getdelays.c
various: Fix spelling of "asynchronous" in comments.
Fix misspellings of "whether" in comments.
eisa: Fix spelling of "asynchronous".
various: Fix spelling of "registered" in comments.
doc: fix quite a few typos within Documentation
target: iscsi: fix comment typos in target/iscsi drivers
treewide: fix typo of "suport" in various comments and Kconfig
treewide: fix typo of "suppport" in various comments
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
"These are late-v3.7 pending fixes for tracing."
Fix up trivial conflict in kernel/trace/ring_buffer.c: the NULL pointer
fix clashed with the change of type of the 'ret' variable.
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ring-buffer: Fix race between integrity check and readers
ring-buffer: Fix NULL pointer if rb_set_head_page() fails
ftrace: Clear bits properly in reset_iter_read()
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core
Pull ftrace updates from Steve Rostedt.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc into perf/core
Pull uprobes fixes, cleanups and preparation for the ARM port from Oleg Nesterov.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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I've legally changed my name with New York State, the US Social Security
Administration, et al. This patch propagates the name change and change
in initials and login to comments in the kernel source as well.
Signed-off-by: Nadia Yvette Chambers <nyc@holomorphy.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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The function rb_check_pages() was added to make sure the ring buffer's
pages were sane. This check is done when the ring buffer size is modified
as well as when the iterator is released (closing the "trace" file),
as that was considered a non fast path and a good place to do a sanity
check.
The problem is that the check does not have any locks around it.
If one process were to read the trace file, and another were to read
the raw binary file, the check could happen while the reader is reading
the file.
The issues with this is that the check requires to clear the HEAD page
before doing the full check and it restores it afterward. But readers
require the HEAD page to exist before it can read the buffer, otherwise
it gives a nasty warning and disables the buffer.
By adding the reader lock around the check, this keeps the race from
happening.
Cc: stable@vger.kernel.org # 3.6
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The function rb_set_head_page() searches the list of ring buffer
pages for a the page that has the HEAD page flag set. If it does
not find it, it will do a WARN_ON(), disable the ring buffer and
return NULL, as this should never happen.
But if this bug happens to happen, not all callers of this function
can handle a NULL pointer being returned from it. That needs to be
fixed.
Cc: stable@vger.kernel.org # 3.0+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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