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  1. 21 Jan, 2013 10 commits
    • Steven Rostedt's avatar
      tracing/fgraph: Add max_graph_depth to limit function_graph depth · 8741db53
      Steven Rostedt authored 
      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: default avatarSteven Rostedt <rostedt@goodmis.org>
      8741db53
    • Steven Rostedt's avatar
      tracing/lockdep: Disable lockdep first in entering NMI · 0f1ac8fd
      Steven Rostedt authored 
      When function tracing with either debug locks enabled or tracing
preempt disabled, the add_preempt_count() is traced. This is an
issue with lockdep and function tracing. As function tracing
can disable interrupts, and lockdep records that change,
lockdep may not be able to handle this recursion if it happens from
an NMI context.

The first thing that an NMI does is:

 #define nmi_enter()					\
	do {							\
		ftrace_nmi_enter();				\
		BUG_ON(in_nmi());				\
		add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
		lockdep_off();					\
		rcu_nmi_enter();				\
		trace_hardirq_enter();				\
	} while (0)

When the add_preempt_count() is traced, and the tracing callback
disables interrupts, it will jump into the lockdep code. There's
some places in lockdep that can't handle this re-entrance, and
causes lockdep to fail.

As the lockdep_off() (and lockdep_on) is a simple:

void lockdep_off(void)
{
	current->lockdep_recursion++;
}

and is never traced, it can be called first in nmi_enter()
and lockdep_on() last in nmi_exit().

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      0f1ac8fd
    • Steven Rostedt's avatar
      tracing: Remove unneeded check of max_tr->buffer before tracing_reset · 84c6cf0d
      Steven Rostedt authored 
      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: default avatarSteven Rostedt <rostedt@goodmis.org>
      84c6cf0d
    • Hiraku Toyooka's avatar
      tracing: Add checks if tr->buffer is NULL in tracing_reset{_online_cpus} · a5416411
      Hiraku Toyooka authored 
      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@liselsiaSigned-off-by: default avatarHiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      a5416411
    • Fengguang Wu's avatar
      tracing/syscalls: Make local functions static · 6aea49cb
      Fengguang Wu authored 
      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: default avatarFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      6aea49cb
    • Jovi Zhang's avatar
      tracing: Verify target file before registering a uprobe event · d24d7dbf
      Jovi Zhang authored 
      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: default avatarJovi Zhang <bookjovi@gmail.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
[ cleaned up whitespace and removed redundant IS_DIR() check ]
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      d24d7dbf
    • Shan Wei's avatar
      tracing: Use this_cpu_ptr per-cpu helper · d8a0349c
      Shan Wei authored 
      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.comReviewed-by: default avatarChristoph Lameter <cl@linux.com>
Signed-off-by: default avatarShan Wei <davidshan@tencent.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      d8a0349c
    • Steven Rostedt's avatar
      ring-buffer: Remove unnecessary recusive call in rb_advance_iter() · 771e0384
      Steven Rostedt authored 
      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: default avatarSteven Rostedt <rostedt@goodmis.org>
      771e0384
    • Steven Rostedt's avatar
      tracing: Fix sparse warning with is_signed_type() macro · 418c59e4
      Steven Rostedt authored 
      Sparse complains when is_signed_type() is used on a pointer.
This macro is needed for the format output used for ftrace
and perf, to know if a binary field is a signed type or not.
The is_signed_type() macro is used against all fields that are
recorded by events to automate the operation.

The problem sparse has is with the current way is_signed_type()
works:

  ((type)-1 < 0)

If "type" is a poiner, than sparse does not like it being compared
to an integer (zero). The simple fix is to just give zero the
same type. The runtime result stays the same.
Reported-by: default avatarRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      418c59e4
    • Steven Rostedt's avatar
      ftrace: Be first to run code modification on modules · c1bf08ac
      Steven Rostedt authored 
      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: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reported-by: default avatarFrank Ch. Eigler <fche@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      c1bf08ac
  3. 18 Jan, 2013 1 commit
  5. 17 Jan, 2013 2 commits
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux · 72ffaa48
      Linus Torvalds authored 
      Pull more s390 patches from Martin Schwidefsky:
 "A couple of bug fixes: one of the transparent huge page primitives is
  broken, the sched_clock function overflows after 417 days, the XFS
  module has grown too large for -fpic and the new pci code has broken
  normal channel subsystem notifications."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/chsc: fix SEI usage
  s390/time: fix sched_clock() overflow
  s390: use -fPIC for module compile
  s390/mm: fix pmd_pfn() for thp
      72ffaa48
    • Linus Torvalds's avatar
      Merge tag 'for-linus-v3.8-rc4' of git://oss.sgi.com/xfs/xfs · dfdebc24
      Linus Torvalds authored 
      Pull xfs bugfixes from Ben Myers:

 - fix(es) for compound buffers

 - fix for dquot soft timer asserts due to overflow of d_blk_softlimit

 - fix for regression in dir v2 code introduced in commit 20f7e9f3
   ("xfs: factor dir2 block read operations")

* tag 'for-linus-v3.8-rc4' of git://oss.sgi.com/xfs/xfs:
  xfs: recalculate leaf entry pointer after compacting a dir2 block
  xfs: remove int casts from debug dquot soft limit timer asserts
  xfs: fix the multi-segment log buffer format
  xfs: fix segment in xfs_buf_item_format_segment
  xfs: rename bli_format to avoid confusion with bli_formats
  xfs: use b_maps[] for discontiguous buffers
      dfdebc24
  7. 16 Jan, 2013 24 commits
  9. 15 Jan, 2013 3 commits
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