While debugging a latency with someone on IRC (mirage335) on #linux-rt (OFTC),
we discovered that the stacktrace output of the latency tracers
(preemptirqsoff) was empty.
This bug was caused by the creation of the dynamic length stack trace
again (like commit 12b5da3 "tracing: Fix ent_size in trace output" was).
This bug is caused by the latency tracers requiring the next event
to determine the time between the current event and the next. But by
grabbing the next event, the iter->ent_size is set to the next event
instead of the current one. As the stacktrace event is the last event,
this makes the ent_size zero and causes nothing to be printed for
the stack trace. The dynamic stacktrace uses the ent_size to determine
how much of the stack can be printed. The ent_size of zero means
no stack.
The simple fix is to save the iter->ent_size before finding the next event.
Note, mirage335 asked to remain anonymous from LKML and git, so I will
not add the Reported-by and Tested-by tags, even though he did report
the issue and tested the fix.
Cc: stable@vger.kernel.org # 3.1+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The change to make tracing_on affect only the ftrace ring buffer, caused
a bug where it wont affect any ring buffer. The problem was that the buffer
of the trace_array was passed to the write function and not the trace array
itself.
The trace_array can change the buffer when running a latency tracer. If this
happens, then the buffer being disabled may not be the buffer currently used
by ftrace. This will cause the tracing_on file to become useless.
The simple fix is to pass the trace_array to the write function instead of
the buffer. Then the actual buffer may be changed.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Today's -next fails to link for me:
kernel/built-in.o:(.data+0x178e50): undefined reference to `perf_ftrace_event_register'
It looks like multiple fixes have been merged for the issue fixed by
commit fa73dc9 (tracing: Fix build breakage without CONFIG_PERF_EVENTS)
though I can't identify the other changes that have gone in at the
minute, it's possible that the changes which caused the breakage fixed
by the previous commit got dropped but the fix made it in.
Link: http://lkml.kernel.org/r/1334307179-21255-1-git-send-email-broonie@opensource.wolfsonmicro.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Merge batch of fixes from Andrew Morton:
"The simple_open() cleanup was held back while I wanted for laggards to
merge things.
I still need to send a few checkpoint/restore patches. I've been
wobbly about merging them because I'm wobbly about the overall
prospects for success of the project. But after speaking with Pavel
at the LSF conference, it sounds like they're further toward
completion than I feared - apparently davem is at the "has stopped
complaining" stage regarding the net changes. So I need to go back
and re-review those patchs and their (lengthy) discussion."
* emailed from Andrew Morton <akpm@linux-foundation.org>: (16 patches)
memcg swap: use mem_cgroup_uncharge_swap fix
backlight: add driver for DA9052/53 PMIC v1
C6X: use set_current_blocked() and block_sigmask()
MAINTAINERS: add entry for sparse checker
MAINTAINERS: fix REMOTEPROC F: typo
alpha: use set_current_blocked() and block_sigmask()
simple_open: automatically convert to simple_open()
scripts/coccinelle/api/simple_open.cocci: semantic patch for simple_open()
libfs: add simple_open()
hugetlbfs: remove unregister_filesystem() when initializing module
drivers/rtc/rtc-88pm860x.c: fix rtc irq enable callback
fs/xattr.c:setxattr(): improve handling of allocation failures
fs/xattr.c:listxattr(): fall back to vmalloc() if kmalloc() failed
fs/xattr.c: suppress page allocation failure warnings from sys_listxattr()
sysrq: use SEND_SIG_FORCED instead of force_sig()
proc: fix mount -t proc -o AAA
Many users of debugfs copy the implementation of default_open() when
they want to support a custom read/write function op. This leads to a
proliferation of the default_open() implementation across the entire
tree.
Now that the common implementation has been consolidated into libfs we
can replace all the users of this function with simple_open().
This replacement was done with the following semantic patch:
<smpl>
@ open @
identifier open_f != simple_open;
identifier i, f;
@@
-int open_f(struct inode *i, struct file *f)
-{
(
-if (i->i_private)
-f->private_data = i->i_private;
|
-f->private_data = i->i_private;
)
-return 0;
-}
@ has_open depends on open @
identifier fops;
identifier open.open_f;
@@
struct file_operations fops = {
...
-.open = open_f,
+.open = simple_open,
...
};
</smpl>
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When reading the trace file, the records of each of the per_cpu buffers
are examined to find the next event to print out. At the point of looking
at the event, the size of the event is recorded. But if the first event is
chosen, the other events in the other CPU buffers will reset the event size
that is stored in the iterator descriptor, causing the event size passed to
the output functions to be incorrect.
In most cases this is not a problem, but for the case of stack traces, it
is. With the change to the stack tracing to record a dynamic number of
back traces, the output depends on the size of the entry instead of the
fixed 8 back traces. When the entry size is not correct, the back traces
would not be fully printed.
Note, reading from the per-cpu trace files were not affected.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull vfs pile 1 from Al Viro:
"This is _not_ all; in particular, Miklos' and Jan's stuff is not there
yet."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits)
ext4: initialization of ext4_li_mtx needs to be done earlier
debugfs-related mode_t whack-a-mole
hfsplus: add an ioctl to bless files
hfsplus: change finder_info to u32
hfsplus: initialise userflags
qnx4: new helper - try_extent()
qnx4: get rid of qnx4_bread/qnx4_getblk
take removal of PF_FORKNOEXEC to flush_old_exec()
trim includes in inode.c
um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it
um: embed ->stub_pages[] into mmu_context
gadgetfs: list_for_each_safe() misuse
ocfs2: fix leaks on failure exits in module_init
ecryptfs: make register_filesystem() the last potential failure exit
ntfs: forgets to unregister sysctls on register_filesystem() failure
logfs: missing cleanup on register_filesystem() failure
jfs: mising cleanup on register_filesystem() failure
make configfs_pin_fs() return root dentry on success
configfs: configfs_create_dir() has parent dentry in dentry->d_parent
configfs: sanitize configfs_create()
...
Today's -next fails to build for me:
CC kernel/trace/trace_export.o
In file included from kernel/trace/trace_export.c:197: kernel/trace/trace_entries.h:58: error: 'perf_ftrace_event_register' undeclared here (not in a function)
make[2]: *** [kernel/trace/trace_export.o] Error 1
make[1]: *** [kernel/trace] Error 2
make: *** [kernel] Error 2
because as of ced390 (ftrace, perf: Add support to use function
tracepoint in perf) perf_trace_event_register() is declared in trace.h
only if CONFIG_PERF_EVENTS is enabled but I don't have that set.
Ensure that we always have a definition of perf_trace_event_register()
by making the definition unconditional.
Link: http://lkml.kernel.org/r/1330426967-17067-1-git-send-email-broonie@opensource.wolfsonmicro.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When CONFIG_DYNAMIC_FTRACE is not set, some archs (ARM) test
the variable function_trace_function to determine if it should
call the function tracer. If it is not set to ftrace_stub, then
it will call the function and return, and not call the function
graph tracer.
But some of these archs (ARM) do not have the assembly code
to test if function tracing is enabled or not (quick stop of tracing)
and it calls the helper routine ftrace_test_stop_func() instead.
If function tracer is enabled and then disabled, the variable
ftrace_trace_function is still set to the helper routine
ftrace_test_stop_func(), and not to ftrace_stub. This will
prevent the function graph tracer from ever running.
Output before patch
/debug/tracing # echo function > current_tracer
/debug/tracing # echo function_graph > current_tracer
/debug/tracing # cat trace
Output after patch
/debug/tracing # echo function > current_tracer
/debug/tracing # echo function_graph > current_tracer
/debug/tracing # cat trace
0) ! 253.375 us | } /* irq_enter */
0) | generic_handle_irq() {
0) | handle_fasteoi_irq() {
0) 9.208 us | _raw_spin_lock();
0) | handle_irq_event() {
0) | handle_irq_event_percpu() {
Signed-off-by: Rajesh Bhagat <rajesh.lnx@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As ftrace_dump() (called by ftrace_dump_on_oops) disables interrupts
as it dumps its output to the console, it can keep interrupts disabled
for long periods of time. This is likely to trigger the NMI watchdog,
and it can disrupt the output of critical data.
Add a touch_nmi_watchdog() to each event that is written to the screen
to keep the NMI watchdog from affecting the output.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
On PowerPC, FUNCTION_TRACER selects FRAME_POINTER, even
though the architecture does not support it.
This causes the following warning:
warning: (LOCKDEP && FAULT_INJECTION_STACKTRACE_FILTER && LATENCYTOP && FUNCTION_TRACER && KMEMCHECK) selects FRAME_POINTER which has unmet direct dependencies (DEBUG_KERNEL && (CRIS || M68K || FRV || UML || AVR32 || SUPERH || BLACKFIN || MN10300) || ARCH_WANT_FRAME_POINTERS)
So remove the warning by adding the extra condition
"if !PPC" to FUNCTION_TRACER for FRAME_POINTER selection
Link: http://lkml.kernel.org/r/1330330101-8618-1-git-send-email-gerlando.falauto@keymile.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As the ring-buffer code is being used by other facilities in the
kernel, having tracing_on file disable *all* buffers is not a desired
affect. It should only disable the ftrace buffers that are being used.
Move the code into the trace.c file and use the buffer disabling
for tracing_on() and tracing_off(). This way only the ftrace buffers
will be affected by them and other kernel utilities will not be
confused to why their output suddenly stopped.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Adding support to filter function trace event via perf
interface. It is now possible to use filter interface
in the perf tool like:
perf record -e ftrace:function --filter="(ip == mm_*)" ls
The filter syntax is restricted to the the 'ip' field only,
and following operators are accepted '==' '!=' '||', ending
up with the filter strings like:
ip == f1[, ]f2 ... || ip != f3[, ]f4 ...
with comma ',' or space ' ' as a function separator. If the
space ' ' is used as a separator, the right side of the
assignment needs to be enclosed in double quotes '"', e.g.:
perf record -e ftrace:function --filter '(ip == do_execve,sys_*,ext*)' ls
perf record -e ftrace:function --filter '(ip == "do_execve,sys_*,ext*")' ls
perf record -e ftrace:function --filter '(ip == "do_execve sys_* ext*")' ls
The '==' operator adds trace filter with same effect as would
be added via set_ftrace_filter file.
The '!=' operator adds trace filter with same effect as would
be added via set_ftrace_notrace file.
The right side of the '!=', '==' operators is list of functions
or regexp. to be added to filter separated by space.
The '||' operator is used for connecting multiple filter definitions
together. It is possible to have more than one '==' and '!='
operators within one filter string.
Link: http://lkml.kernel.org/r/1329317514-8131-8-git-send-email-jolsa@redhat.com
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Adding FILTER_TRACE_FN event field type for function tracepoint
event, so it can be properly recognized within filtering code.
Currently all fields of ftrace subsystem events share the common
field type FILTER_OTHER. Since the function trace fields need
special care within the filtering code we need to recognize it
properly, hence adding the FILTER_TRACE_FN event type.
Adding filter parameter to the FTRACE_ENTRY macro, to specify the
filter field type for the event.
Link: http://lkml.kernel.org/r/1329317514-8131-7-git-send-email-jolsa@redhat.com
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Adding perf registration support for the ftrace function event,
so it is now possible to register it via perf interface.
The perf_event struct statically contains ftrace_ops as a handle
for function tracer. The function tracer is registered/unregistered
in open/close actions.
To be efficient, we enable/disable ftrace_ops each time the traced
process is scheduled in/out (via TRACE_REG_PERF_(ADD|DELL) handlers).
This way tracing is enabled only when the process is running.
Intentionally using this way instead of the event's hw state
PERF_HES_STOPPED, which would not disable the ftrace_ops.
It is now possible to use function trace within perf commands
like:
perf record -e ftrace:function ls
perf stat -e ftrace:function ls
Allowed only for root.
Link: http://lkml.kernel.org/r/1329317514-8131-6-git-send-email-jolsa@redhat.com
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Adding TRACE_REG_PERF_OPEN and TRACE_REG_PERF_CLOSE to differentiate
register/unregister from open/close actions.
The register/unregister actions are invoked for the first/last
tracepoint user when opening/closing the event.
The open/close actions are invoked for each tracepoint user when
opening/closing the event.
Link: http://lkml.kernel.org/r/1329317514-8131-3-git-send-email-jolsa@redhat.com
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Adding a way to temporarily enable/disable ftrace_ops. The change
follows the same way as 'global' ftrace_ops are done.
Introducing 2 global ftrace_ops - control_ops and ftrace_control_list
which take over all ftrace_ops registered with FTRACE_OPS_FL_CONTROL
flag. In addition new per cpu flag called 'disabled' is also added to
ftrace_ops to provide the control information for each cpu.
When ftrace_ops with FTRACE_OPS_FL_CONTROL is registered, it is
set as disabled for all cpus.
The ftrace_control_list contains all the registered 'control' ftrace_ops.
The control_ops provides function which iterates ftrace_control_list
and does the check for 'disabled' flag on current cpu.
Adding 3 inline functions:
ftrace_function_local_disable/ftrace_function_local_enable
- enable/disable the ftrace_ops on current cpu
ftrace_function_local_disabled
- get disabled ftrace_ops::disabled value for current cpu
Link: http://lkml.kernel.org/r/1329317514-8131-2-git-send-email-jolsa@redhat.com
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If more than one __print_*() function is used in a tracepoint
(__print_flags(), __print_symbols(), etc), then the temp seq buffer will
not be zero on entry. Using the temp seq buffer's length to know if
data has been printed or not in the current function is incorrect and
may produce incorrect results.
Currently, no in-tree tracepoint causes this bug, but new ones may
be created.
Cc: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If __print_flags() is used after another __print_*() function, the
temp seq_file buffer will not be empty on entry, and the delimiter will
be printed even though there's just one field. We get something like:
|S
instead of just:
S
This is because the length of the temp seq buffer is used to determine
if the delimiter is printed or not. But this algorithm fails when
the seq buffer is not empty on entry, and the delimiter will be printed
because it thinks that a previous field was already printed.
Link: http://lkml.kernel.org/r/1329650167-480655-1-git-send-email-avagin@openvz.org
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
