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  1. 21 1月, 2009 4 次提交
    • S
      trace: stop all recording to ring buffer on ftrace_dump · a442e5e0
      由 Steven Rostedt 提交于 
      Impact: limit ftrace dump output

Currently ftrace_dump only calls ftrace_kill that is a fast way
to prevent the function tracer functions from being called (just sets
a flag and clears the function to call, nothing else). It is better
to also turn off any recording to the ring buffers as well.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      a442e5e0
    • S
      trace: print ftrace_dump at KERN_EMERG log level · faf6861e
      由 Steven Rostedt 提交于 
      Impact: fix to print out ftrace_dump when expected

I was debugging a hard race condition to only find out that
after I hit the race, my log level was not at level to show
KERN_INFO. The time it took to trigger the race was wasted because
I did not capture the trace.

Since ftrace_dump is only called from kernel oops (and only when
it is set in the kernel command line to do so), or when a
developer adds it to their own local tree, the log level of
the print should be at KERN_EMERG to make sure the print appears.

ftrace_dump is not called by a normal user setup, and will not
add extra unwanted print out to the console. There is no reason
it should be at KERN_INFO.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      faf6861e
    • L
      ring_buffer: reset write when reserve buffer fail · 551b4048
      由 Lai Jiangshan 提交于 
      Impact: reset struct buffer_page.write when interrupt storm

if struct buffer_page.write is not reset, any succedent committing
will corrupted ring_buffer:

static inline void
rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer)
{
	......
		cpu_buffer->commit_page->commit =
			cpu_buffer->commit_page->write;
	......
}

when "if (RB_WARN_ON(cpu_buffer, next_page == reader_page))", ring_buffer
is disabled, but some reserved buffers may haven't been committed.
we need reset struct buffer_page.write.

when "if (unlikely(next_page == cpu_buffer->commit_page))", ring_buffer
is still available, we should not corrupt it.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      551b4048
    • F
      tracing/function-graph-tracer: fix a regression while suspend to disk · 00f57f54
      由 Frederic Weisbecker 提交于 
      Impact: fix a crash while kernel image restore

When the function graph tracer is running and while suspend to disk, some racy
and dangerous things happen against this tracer.

The current task will save its registers including the stack pointer which
contains the return address hooked by the tracer. But the current task will
continue to enter other functions after that to save the memory, and then
it will store other return addresses, and finally loose the old depth which
matches the return address saved in the old stack (during the registers saving).

So on image restore, the code will return to wrong addresses.
And there are other things: on restore, the task will have it's "current"
pointer overwritten during registers restoring....switching from one task to
another... That would be insane to try to trace function graphs at these
stages.

This patch makes the function graph tracer listening on power events, making
it's tracing disabled for the current task (the one that performs the
hibernation work) while suspend/resume to disk, making the tracing safe
during hibernation.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      00f57f54
  3. 20 1月, 2009 1 次提交
    • S
      ring-buffer: fix alignment problem · 082605de
      由 Steven Rostedt 提交于 
      Impact: fix to allow some archs to use the ring buffer

Commits in the ring buffer are checked by pointer arithmetic.
If the calculation is incorrect, then the commits will never take
place and the buffer will simply fill up and report an error.

Each page in the ring buffer has a small header:

struct buffer_data_page {
	u64		time_stamp;
	local_t		commit;
	unsigned char	data[];
};

Unfortuntely, some of the calculations used sizeof(struct buffer_data_page)
to know the size of the header. But this is incorrect on some archs,
where sizeof(struct buffer_data_page) does not equal
offsetof(struct buffer_data_page, data), and on those archs, the commits
are never processed.

This patch replaces the sizeof with offsetof.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      082605de
  5. 17 1月, 2009 26 次提交
  7. 16 1月, 2009 9 次提交