Impact: fix potential crash on subsystem filter expression freeing
When making a copy of the predicate, pred->field_name needs to be
duplicated in the copy as well, otherwise bad things can happen due to
later multiple frees of the same string.
This affects only per-subsystem event filtering.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237796802.7527.39.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When we want to filter an event, the filter test is done after
the event is commited to the ring-buffer to be discarded later if
needed.
But a reader could be reading this event while we are trying to discard
it. Other kind of racy events can even happen because the event is
commited and can be read and/or consumed.
What we want is to discard the event before committing it.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1237763919-21505-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: display events when they arrive
Now that the events don't use wake_up() anymore, we need the nop
tracer to poll waiting for events on the pipe. Especially because
nop is useful to look at orphan traces types (traces types that
don't rely on specific tracers) because it doesn't produce traces
itself.
And unlike other tracers that trigger specific traces periodically,
nop triggers no traces by itself that can wake him.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix hard-lockup with sched switch events
Some ftrace events, such as sched wakeup, can be traced
while the runqueue lock is hold. Since they are using
trace_current_buffer_unlock_commit(), they call wake_up()
which can try to grab the runqueue lock too, resulting in
a deadlock.
Now for all event, we call a new helper:
trace_nowake_buffer_unlock_commit() which do pretty the same than
trace_current_buffer_unlock_commit() except than it doesn't call
trace_wake_up().
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix potential kfree of random data in (rare) failure path
Zero-initialize the field structure.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1237710639.7703.46.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds per-subsystem filtering to the event tracing subsystem.
It adds a 'filter' debugfs file to each subsystem directory. This file
can be written to to set filters; reading from it will display the
current set of filters set for that subsystem.
Basically what it does is propagate the filter down to each event
contained in the subsystem. If a particular event doesn't have a field
with the name specified in the filter, it simply doesn't get set for
that event. You can verify whether or not the filter was set for a
particular event by looking at the filter file for that event.
As with per-event filters, compound expressions are supported, echoing
'0' to the subsystem's filter file clears all filters in the subsystem,
etc.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710677.7703.49.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds per-event filtering to the event tracing subsystem.
It adds a 'filter' debugfs file to each event directory. This file can
be written to to set filters; reading from it will display the current
set of filters set for that event.
Basically, any field listed in the 'format' file for an event can be
filtered on (including strings, but not yet other array types) using
either matching ('==') or non-matching ('!=') 'predicates'. A
'predicate' can be either a single expression:
# echo pid != 0 > filter
# cat filter
pid != 0
or a compound expression of up to 8 sub-expressions combined using '&&'
or '||':
# echo comm == Xorg > filter
# echo "&& sig != 29" > filter
# cat filter
comm == Xorg
&& sig != 29
Only events having field values matching an expression will be available
in the trace output; non-matching events are discarded.
Note that a compound expression is built up by echoing each
sub-expression separately - it's not the most efficient way to do
things, but it keeps the parser simple and assumes that compound
expressions will be relatively uncommon. In any case, a subsequent
patch introducing a way to set filters for entire subsystems should
mitigate any need to do this for lots of events.
Setting a filter without an '&&' or '||' clears the previous filter
completely and sets the filter to the new expression:
# cat filter
comm == Xorg
&& sig != 29
# echo comm != Xorg
# cat filter
comm != Xorg
To clear a filter, echo 0 to the filter file:
# echo 0 > filter
# cat filter
none
The limit of 8 predicates for a compound expression is arbitrary - for
efficiency, it's implemented as an array of pointers to predicates, and
8 seemed more than enough for any filter...
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710665.7703.48.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch overloads RINGBUF_TYPE_PADDING to provide a way to discard
events from the ring buffer, for the event-filtering mechanism
introduced in a subsequent patch.
I did the initial version but thanks to Steven Rostedt for adding
the parts that actually made it work. ;-)
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch makes the field descriptions defined for event tracing
available at run-time, for the event-filtering mechanism introduced
in a subsequent patch.
The common event fields are prepended with 'common_' in the format
display, allowing them to be distinguished from the other fields
that might internally have same name and can therefore be
unambiguously used in filters.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710639.7703.46.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: detect tracing related hangs
Sometimes, with some configs, the function graph tracer can make
the timer interrupt too much slow, hanging the kernel in an endless
loop of timer interrupts servicing.
As suggested by Ingo, this patch brings a watchdog which stops the
selftest after a defined number of functions traced, definitely
disabling this tracer.
For those who want to debug the cause of the function graph trace
hang, you can pass the ftrace_dump_on_oops kernel parameter to dump
the traces after this hang detection.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: widen user-space visibe event IDs to all events
Previously only TRACE_EVENT events got ids, because only they
generated raw output which needs to be demuxed from the trace.
In order to provide a unique ID for each event, register everybody,
regardless.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.464914218@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The libaio test harness turned up a problem whereby lookup_ioctx on a
bogus io context was returning the 1 valid io context from the list
(harness/cases/3.p).
Because of that, an extra put_iocontext was done, and when the process
exited, it hit a BUG_ON in the put_iocontext macro called from exit_aio
(since we expect a users count of 1 and instead get 0).
The problem was introduced by "aio: make the lookup_ioctx() lockless"
(commit abf137dd77).
Thanks to Zach for pointing out that hlist_for_each_entry_rcu will not
return with a NULL tpos at the end of the loop, even if the entry was
not found.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Zach Brown <zach.brown@oracle.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove a source of fput() call from inside IRQ context. Myself, like Eric,
wasn't able to reproduce an fput() call from IRQ context, but Jeff said he was
able to, with the attached test program. Independently from this, the bug is
conceptually there, so we might be better off fixing it. This patch adds an
optimization similar to the one we already do on ->ki_filp, on ->ki_eventfd.
Playing with ->f_count directly is not pretty in general, but the alternative
here would be to add a brand new delayed fput() infrastructure, that I'm not
sure is worth it.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sam Ravnborg says:
"We have several architectures that plays strange games with $(CC) and
$(CROSS_COMPILE).
So we need to postpone any use of $(call cc-option..) until we have
included the arch specific Makefile so we try with the correct $(CC)
version."
Requested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
[S390] make page table upgrade work again
[S390] make page table walking more robust
[S390] Dont check for pfn_valid() in uaccess_pt.c
[S390] ftrace/mcount: fix kernel stack backchain
[S390] topology: define SD_MC_INIT to fix performance regression
[S390] __div64_31 broken for CONFIG_MARCH_G5
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
Btrfs: Clear space_info full when adding new devices
Btrfs: Fix locking around adding new space_info
With the added TRACE_EVENT macro, the events no longer appear in
the function graph tracer. This was because the function graph
did not know how to display the entries. The graph tracer was
only aware of its own entries and the printk entries.
By using the event call back feature, the graph tracer can now display
the events.
# echo irq > /debug/tracing/set_event
Which can show:
0) | handle_IRQ_event() {
0) | /* irq_handler_entry: irq=48 handler=eth0 */
0) | e1000_intr() {
0) 0.926 us | __napi_schedule();
0) 3.888 us | }
0) | /* irq_handler_exit: irq=48 return=handled */
0) 0.655 us | runqueue_is_locked();
0) | __wake_up() {
0) 0.831 us | _spin_lock_irqsave();
The irq entry and exit events show up as comments.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
