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  1. 08 8月, 2009 1 次提交
  3. 06 8月, 2009 3 次提交
    • R
      ring-buffer: Fix advance of reader in rb_buffer_peek() · 469535a5
      由 Robert Richter 提交于 
      When calling rb_buffer_peek() from ring_buffer_consume() and a
padding event is returned, the function rb_advance_reader() is
called twice. This may lead to missing samples or under high
workloads to the warning below. This patch fixes this. If a padding
event is returned by rb_buffer_peek() it will be consumed by the
calling function now.

Also, I simplified some code in ring_buffer_consume().

------------[ cut here ]------------
WARNING: at /dev/shm/.source/linux/kernel/trace/ring_buffer.c:2289 rb_advance_reader+0x2e/0xc5()
Hardware name: Anaheim
Modules linked in:
Pid: 29, comm: events/2 Tainted: G        W  2.6.31-rc3-oprofile-x86_64-standard-00059-g5050dc2 #1
Call Trace:
[<ffffffff8106776f>] ? rb_advance_reader+0x2e/0xc5
[<ffffffff81039ffe>] warn_slowpath_common+0x77/0x8f
[<ffffffff8103a025>] warn_slowpath_null+0xf/0x11
[<ffffffff8106776f>] rb_advance_reader+0x2e/0xc5
[<ffffffff81068bda>] ring_buffer_consume+0xa0/0xd2
[<ffffffff81326933>] op_cpu_buffer_read_entry+0x21/0x9e
[<ffffffff810be3af>] ? __find_get_block+0x4b/0x165
[<ffffffff8132749b>] sync_buffer+0xa5/0x401
[<ffffffff810be3af>] ? __find_get_block+0x4b/0x165
[<ffffffff81326c1b>] ? wq_sync_buffer+0x0/0x78
[<ffffffff81326c76>] wq_sync_buffer+0x5b/0x78
[<ffffffff8104aa30>] worker_thread+0x113/0x1ac
[<ffffffff8104dd95>] ? autoremove_wake_function+0x0/0x38
[<ffffffff8104a91d>] ? worker_thread+0x0/0x1ac
[<ffffffff8104dc9a>] kthread+0x88/0x92
[<ffffffff8100bdba>] child_rip+0xa/0x20
[<ffffffff8104dc12>] ? kthread+0x0/0x92
[<ffffffff8100bdb0>] ? child_rip+0x0/0x20
---[ end trace f561c0a58fcc89bd ]---

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@kernel.org>
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      469535a5
    • S
      ring-buffer: do not disable ring buffer on oops_in_progress · 464e85eb
      由 Steven Rostedt 提交于 
      The commit:

  commit e0fdace1
  Author: David Miller <davem@davemloft.net>
  Date:   Fri Aug 1 01:11:22 2008 -0700

    debug_locks: set oops_in_progress if we will log messages.

    Otherwise lock debugging messages on runqueue locks can deadlock the
    system due to the wakeups performed by printk().
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Will permanently set oops_in_progress on any lockdep failure.
When this triggers it will cause any read from the ring buffer to
permanently disable the ring buffer (not to mention no locking of
printk).

This patch removes the check. It keeps the print in NMI which makes
sense. This is probably OK, since the ring buffer should not cause
something to set oops_in_progress anyway.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      464e85eb
    • S
      ring-buffer: fix check of try_to_discard result · 0f2541d2
      由 Steven Rostedt 提交于 
      The function ring_buffer_discard_commit inversed the code path
of the result of try_to_discard. It should skip incrementing the
entry counter if try_to_discard succeeded. But instead, it increments
the entry conder if it succeeded to discard, and does not increment
it if it fails.

The result of this bug is that filtering will make the stat counters
incorrect.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      0f2541d2
  5. 29 7月, 2009 2 次提交
    • L
      tracing: Fix missing function_graph events when we splice_read from trace_pipe · 74e7ff8c
      由 Lai Jiangshan 提交于 
      About a half events are missing when we splice_read
from trace_pipe. They are unexpectedly consumed because we ignore
the TRACE_TYPE_NO_CONSUME return value used by the function graph
tracer when it needs to consume the events by itself to walk on
the ring buffer.

The same problem appears with ftrace_dump()

Example of an output before this patch:

1)               |      ktime_get_real() {
1)   2.846 us    |          read_hpet();
1)   4.558 us    |        }
1)   6.195 us    |      }

After this patch:

0)               |      ktime_get_real() {
0)               |        getnstimeofday() {
0)   1.960 us    |          read_hpet();
0)   3.597 us    |        }
0)   5.196 us    |      }

The fix also applies on 2.6.30
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@kernel.org
LKML-Reference: <4A6EEC52.90704@cn.fujitsu.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      74e7ff8c
    • L
      tracing: Fix invalid function_graph entry · 38ceb592
      由 Lai Jiangshan 提交于 
      When print_graph_entry() computes a function call entry event, it needs
to also check the next entry to guess if it matches the return event of
the current function entry.
In order to look at this next event, it needs to consume the current
entry before going ahead in the ring buffer.

However, if the current event that gets consumed is the last one in the
ring buffer head page, the ring_buffer may reuse the page for writers.
The consumed entry will then become invalid because of possible
racy overwriting.

Me must then handle this entry by making a copy of it.

The fix also applies on 2.6.30
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@kernel.org
LKML-Reference: <4A6EEAEC.3050508@cn.fujitsu.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      38ceb592
  7. 23 7月, 2009 5 次提交
  9. 17 7月, 2009 1 次提交
    • X
      tracing/function: Fix the return value of ftrace_trace_onoff_callback() · 04aef32d
      由 Xiao Guangrong 提交于 
      ftrace_trace_onoff_callback() will return an error even if we do the
right operation, for example:

 # echo _spin_*:traceon:10 > set_ftrace_filter
 -bash: echo: write error: Invalid argument
 # cat set_ftrace_filter
 #### all functions enabled ####
 _spin_trylock_bh:traceon:count=10
 _spin_unlock_irq:traceon:count=10
 _spin_unlock_bh:traceon:count=10
 _spin_lock_irq:traceon:count=10
 _spin_unlock:traceon:count=10
 _spin_trylock:traceon:count=10
 _spin_unlock_irqrestore:traceon:count=10
 _spin_lock_irqsave:traceon:count=10
 _spin_lock_bh:traceon:count=10
 _spin_lock:traceon:count=10

We want to set _spin_*:traceon:10 to set_ftrace_filter, it complains
with "Invalid argument", but the operation is successful.

This is because ftrace_process_regex() returns the number of functions that
matched the pattern. If the number is not 0, this value is returned
by ftrace_regex_write() whereas we want to return the number of bytes
virtually written.
Also the file offset pointer is not updated in this case.

If the number of matched functions is lower than the number of bytes written
by the user, this results to a reprocessing of the string given by the user with
a lower size, leading to a malformed ftrace regex and then a -EINVAL returned.

So, this patch fixes it by returning 0 if no error occured.
The fix also applies on 2.6.30
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Reviewed-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: stable@kernel.org
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      04aef32d
  11. 13 7月, 2009 2 次提交
  13. 02 7月, 2009 1 次提交
  15. 29 6月, 2009 1 次提交
  17. 27 6月, 2009 2 次提交
  19. 26 6月, 2009 1 次提交
  21. 25 6月, 2009 2 次提交
    • P
      ring-buffer: Make it generally available · 1155de47
      由 Paul Mundt 提交于 
      In hunting down the cause for the hwlat_detector ring buffer spew in
my failed -next builds it became obvious that folks are now treating
ring_buffer as something that is generic independent of tracing and thus,
suitable for public driver consumption.

Given that there are only a few minor areas in ring_buffer that have any
reliance on CONFIG_TRACING or CONFIG_FUNCTION_TRACER, provide stubs for
those and make it generally available.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Cc: Jon Masters <jcm@jonmasters.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090625053012.GB19944@linux-sh.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      1155de47
    • L
      ftrace: Remove duplicate newline · 00e54d08
      由 Li Zefan 提交于 
      Before:
  # echo 'sys_open:traceon:' > set_ftrace_filter
  # echo 'sys_close:traceoff:5' > set_ftrace_filter
  # cat set_ftrace_filter
  #### all functions enabled ####
  sys_open:traceon:unlimited

  sys_close:traceoff:count=0

After:
  # cat set_ftrace_filter
  #### all functions enabled ####
  sys_open:traceon:unlimited
  sys_close:traceoff:count=0
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A4313A7.7030105@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      00e54d08
  23. 24 6月, 2009 8 次提交
  25. 20 6月, 2009 2 次提交
    • F
      tracing/urgent: warn in case of ftrace_start_up inbalance · 9ea1a153
      由 Frederic Weisbecker 提交于 
      Prevent from further ftrace_start_up inbalances so that we avoid
future nop patching omissions with dynamic ftrace.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
      9ea1a153
    • F
      tracing/urgent: fix unbalanced ftrace_start_up · c85a17e2
      由 Frederic Weisbecker 提交于 
      Perfcounter reports the following stats for a wide system
profiling:

 #
 # (2364 samples)
 #
 # Overhead  Symbol
 # ........  ......
 #
    15.40%  [k] mwait_idle_with_hints
     8.29%  [k] read_hpet
     5.75%  [k] ftrace_caller
     3.60%  [k] ftrace_call
     [...]

This snapshot has been taken while neither the function tracer nor
the function graph tracer was running.
With dynamic ftrace, such results show a wrong ftrace behaviour
because all calls to ftrace_caller or ftrace_graph_caller (the patched
calls to mcount) are supposed to be patched into nop if none of those
tracers are running.

The problem occurs after the first run of the function tracer. Once we
launch it a second time, the callsites will never be nopped back,
unless you set custom filters.
For example it happens during the self tests at boot time.
The function tracer selftest runs, and then the dynamic tracing is
tested too. After that, the callsites are left un-nopped.

This is because the reset callback of the function tracer tries to
unregister two ftrace callbacks in once: the common function tracer
and the function tracer with stack backtrace, regardless of which
one is currently in use.
It then creates an unbalance on ftrace_start_up value which is expected
to be zero when the last ftrace callback is unregistered. When it
reaches zero, the FTRACE_DISABLE_CALLS is set on the next ftrace
command, triggering the patching into nop. But since it becomes
unbalanced, ie becomes lower than zero, if the kernel functions
are patched again (as in every further function tracer runs), they
won't ever be nopped back.

Note that ftrace_call and ftrace_graph_call are still patched back
to ftrace_stub in the off case, but not the callers of ftrace_call
and ftrace_graph_caller. It means that the tracing is well deactivated
but we waste a useless call into every kernel function.

This patch just unregisters the right ftrace_ops for the function
tracer on its reset callback and ignores the other one which is
not registered, fixing the unbalance. The problem also happens
is .30
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@kernel.org
      c85a17e2
  27. 19 6月, 2009 2 次提交
    • S
      function-graph: add stack frame test · 71e308a2
      由 Steven Rostedt 提交于 
      In case gcc does something funny with the stack frames, or the return
from function code, we would like to detect that.

An arch may implement passing of a variable that is unique to the
function and can be saved on entering a function and can be tested
when exiting the function. Usually the frame pointer can be used for
this purpose.

This patch also implements this for x86. Where it passes in the stack
frame of the parent function, and will test that frame on exit.

There was a case in x86_32 with optimize for size (-Os) where, for a
few functions, gcc would align the stack frame and place a copy of the
return address into it. The function graph tracer modified the copy and
not the actual return address. On return from the funtion, it did not go
to the tracer hook, but returned to the parent. This broke the function
graph tracer, because the return of the parent (where gcc did not do
this funky manipulation) returned to the location that the child function
was suppose to. This caused strange kernel crashes.

This test detected the problem and pointed out where the issue was.

This modifies the parameters of one of the functions that the arch
specific code calls, so it includes changes to arch code to accommodate
the new prototype.

Note, I notice that the parsic arch implements its own push_return_trace.
This is now a generic function and the ftrace_push_return_trace should be
used instead. This patch does not touch that code.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      71e308a2
    • S
      function-graph: disable when both x86_32 and optimize for size are configured · eb4a0378
      由 Steven Rostedt 提交于 
      On x86_32, when optimize for size is set, gcc may align the frame pointer
and make a copy of the the return address inside the stack frame.
The return address that is located in the stack frame may not be
the one used to return to the calling function. This will break the
function graph tracer.

The function graph tracer replaces the return address with a jump to a hook
function that can trace the exit of the function. If it only replaces
a copy, then the hook will not be called when the function returns.
Worse yet, when the parent function returns, the function graph tracer
will return back to the location of the child function which will
easily crash the kernel with weird results.

To see the problem, when i386 is compiled with -Os we get:

c106be03:       57                      push   %edi
c106be04:       8d 7c 24 08             lea    0x8(%esp),%edi
c106be08:       83 e4 e0                and    $0xffffffe0,%esp
c106be0b:       ff 77 fc                pushl  0xfffffffc(%edi)
c106be0e:       55                      push   %ebp
c106be0f:       89 e5                   mov    %esp,%ebp
c106be11:       57                      push   %edi
c106be12:       56                      push   %esi
c106be13:       53                      push   %ebx
c106be14:       81 ec 8c 00 00 00       sub    $0x8c,%esp
c106be1a:       e8 f5 57 fb ff          call   c1021614 <mcount>

When it is compiled with -O2 instead we get:

c10896f0:       55                      push   %ebp
c10896f1:       89 e5                   mov    %esp,%ebp
c10896f3:       83 ec 28                sub    $0x28,%esp
c10896f6:       89 5d f4                mov    %ebx,0xfffffff4(%ebp)
c10896f9:       89 75 f8                mov    %esi,0xfffffff8(%ebp)
c10896fc:       89 7d fc                mov    %edi,0xfffffffc(%ebp)
c10896ff:       e8 d0 08 fa ff          call   c1029fd4 <mcount>

The compile with -Os will align the stack pointer then set up the
frame pointer (%ebp), and it copies the return address back into
the stack frame. The change to the return address in mcount is done
to the copy and not the real place holder of the return address.

Then compile with -O2 sets up the frame pointer first, this makes
the change to the return address by mcount affect where the function
will jump on exit.
Reported-by: NJake Edge <jake@lwn.net>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      eb4a0378
  29. 18 6月, 2009 5 次提交
    • S
      ring-buffer: have benchmark test print to trace buffer · 4b221f03
      由 Steven Rostedt 提交于 
      Currently the output of the ring buffer benchmark/test prints to
the console. This test runs for ten seconds every ten seconds and
ouputs the result after every iteration. This needlessly fills up
the logs.

This patch makes the ring buffer benchmark/test print to the ftrace
buffer using trace_printk. To view the test results, you must examine
the debug/tracing/trace file.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      4b221f03
    • S
      ring-buffer: do not grab locks in nmi · 8d707e8e
      由 Steven Rostedt 提交于 
      If ftrace_dump_on_oops is set, and an NMI detects a lockup, then it
will need to read from the ring buffer. But the read side of the
ring buffer still takes locks. This patch adds a check on the read
side that if it is in an NMI, then it will disable the ring buffer
and not take any locks.

Reads can still happen on a disabled ring buffer.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      8d707e8e
    • S
      ring-buffer: add locks around rb_per_cpu_empty · d4788207
      由 Steven Rostedt 提交于 
      The checking of whether the buffer is empty or not needs to be serialized
among the readers. Add the reader spin lock around it.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      d4788207
    • S
      ring-buffer: check for less than two in size allocation · 5f78abee
      由 Steven Rostedt 提交于 
      The ring buffer must have at least two pages allocated for the
reader page swap to work.

The page count check will miss the case of a zero size passed in.
Even though a zero size ring buffer would probably fail an allocation,
making the min size check for less than two instead of equal to one makes
the code a bit more robust.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      5f78abee
    • S
      ring-buffer: remove useless compile check for buffer_page size · 0dcd4d6c
      由 Steven Rostedt 提交于 
      The original version of the ring buffer had a hack to map the
page struct that held the pages of the buffer to also be the structure
that the ring buffer would keep the pages in a link list.

This overlap of the page struct was very dangerous and that hack was
removed a while ago.

But there was a check to make sure the buffer_page never became bigger
than the page struct, and would fail the compile if it did. The
check was only meaningful when we had the hack. Now that we have separate
allocated descriptors for the buffer pages, we can remove this check.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      0dcd4d6c
  31. 17 6月, 2009 2 次提交