linux-toradex.git/kernel/trace/ring_buffer.c, branch v2.6.31.12

ring-buffer: Fix memleak in ring_buffer_free()

2009-08-07T16:46:39+00:00

I noticed oprofile memleaked in linux-2.6 current tree,
and tracked this ring-buffer leak.

Signed-off-by: Eric Dumazet 
LKML-Reference: <4A7C06B9.2090302@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Steven Rostedt

ring-buffer: Fix advance of reader in rb_buffer_peek()

2009-08-06T12:20:25+00:00

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:
[] ? rb_advance_reader+0x2e/0xc5
[] warn_slowpath_common+0x77/0x8f
[] warn_slowpath_null+0xf/0x11
[] rb_advance_reader+0x2e/0xc5
[] ring_buffer_consume+0xa0/0xd2
[] op_cpu_buffer_read_entry+0x21/0x9e
[] ? __find_get_block+0x4b/0x165
[] sync_buffer+0xa5/0x401
[] ? __find_get_block+0x4b/0x165
[] ? wq_sync_buffer+0x0/0x78
[] wq_sync_buffer+0x5b/0x78
[] worker_thread+0x113/0x1ac
[] ? autoremove_wake_function+0x0/0x38
[] ? worker_thread+0x0/0x1ac
[] kthread+0x88/0x92
[] child_rip+0xa/0x20
[] ? kthread+0x0/0x92
[] ? child_rip+0x0/0x20
---[ end trace f561c0a58fcc89bd ]---

Cc: Steven Rostedt 
Cc: 
Signed-off-by: Robert Richter 
Signed-off-by: Ingo Molnar

ring-buffer: do not disable ring buffer on oops_in_progress

2009-08-06T00:20:00+00:00

The commit:

  commit e0fdace10e75dac67d906213b780ff1b1a4cc360
  Author: David Miller 
  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: David S. Miller 
    Signed-off-by: Ingo Molnar 

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: Steven Rostedt

ring-buffer: fix check of try_to_discard result

2009-08-06T00:19:59+00:00

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: Steven Rostedt

ring-buffer: Make it generally available

2009-06-25T08:31:30+00:00

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: Paul Mundt 
Cc: Jon Masters 
Cc: Steven Rostedt 
LKML-Reference: <20090625053012.GB19944@linux-sh.org>
Signed-off-by: Ingo Molnar

Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-06-20T17:56:46+00:00

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (24 commits)
  tracing/urgent: warn in case of ftrace_start_up inbalance
  tracing/urgent: fix unbalanced ftrace_start_up
  function-graph: add stack frame test
  function-graph: disable when both x86_32 and optimize for size are configured
  ring-buffer: have benchmark test print to trace buffer
  ring-buffer: do not grab locks in nmi
  ring-buffer: add locks around rb_per_cpu_empty
  ring-buffer: check for less than two in size allocation
  ring-buffer: remove useless compile check for buffer_page size
  ring-buffer: remove useless warn on check
  ring-buffer: use BUF_PAGE_HDR_SIZE in calculating index
  tracing: update sample event documentation
  tracing/filters: fix race between filter setting and module unload
  tracing/filters: free filter_string in destroy_preds()
  ring-buffer: use commit counters for commit pointer accounting
  ring-buffer: remove unused variable
  ring-buffer: have benchmark test handle discarded events
  ring-buffer: prevent adding write in discarded area
  tracing/filters: strloc should be unsigned short
  tracing/filters: operand can be negative
  ...

Fix up kmemcheck-induced conflict in kernel/trace/ring_buffer.c manually

ring-buffer: do not grab locks in nmi

2009-06-17T18:16:27+00:00

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: Steven Rostedt

ring-buffer: add locks around rb_per_cpu_empty

2009-06-17T18:16:23+00:00

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: Steven Rostedt

ring-buffer: check for less than two in size allocation

2009-06-17T18:16:20+00:00

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: Steven Rostedt

ring-buffer: remove useless compile check for buffer_page size

2009-06-17T18:16:07+00:00

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: Steven Rostedt