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  1. 18 6月, 2009 3 次提交
  3. 17 6月, 2009 8 次提交
    • S
      ring-buffer: remove useless warn on check · c6a9d7b5
      由 Steven Rostedt 提交于 
      A check if "write > BUF_PAGE_SIZE" is done right after a

	if (write > BUF_PAGE_SIZE)
		return ...;

Thus the check is actually testing the compiler and not the
kernel. This is useless, remove it.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      c6a9d7b5
    • S
      ring-buffer: use BUF_PAGE_HDR_SIZE in calculating index · 22f470f8
      由 Steven Rostedt 提交于 
      The index of the event is found by masking PAGE_MASK to it and
subtracting the header size. Currently the header size is calculate
by PAGE_SIZE - BUF_PAGE_SIZE, when we already have a macro
BUF_PAGE_HDR_SIZE to define it.

If we want to change BUF_PAGE_SIZE to something less than filling
the rest of the page (this is done for debugging), then we break
the algorithm to find the index.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      22f470f8
    • S
      tracing: update sample event documentation · 44ad18e0
      由 Steven Rostedt 提交于 
      The comments in the sample code is a bit confusing. This patch
cleans them up a little.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      44ad18e0
    • L
      tracing/filters: fix race between filter setting and module unload · 00e95830
      由 Li Zefan 提交于 
      Module unload is protected by event_mutex, while setting filter is
protected by filter_mutex. This leads to the race:

echo 'bar == 0 || bar == 10' \    |
		> sample/filter   |
                                  |  insmod sample.ko
  add_pred("bar == 0")            |
    -> n_preds == 1               |
  add_pred("bar == 100")          |
    -> n_preds == 2               |
                                  |  rmmod sample.ko
                                  |  insmod sample.ko
  add_pred("&&")                  |
    -> n_preds == 1 (should be 3) |

Now event->filter->preds is corrupted. An then when filter_match_preds()
is called, the WARN_ON() in it will be triggered.

To avoid the race, we remove filter_mutex, and replace it with event_mutex.

[ Impact: prevent corruption of filters by module removing and loading ]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A375A4D.6000205@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      00e95830
    • L
      tracing/filters: free filter_string in destroy_preds() · 57be8887
      由 Li Zefan 提交于 
      filter->filter_string is not freed when unloading a module:

 # insmod trace-events-sample.ko
 # echo "bar < 100" > /mnt/tracing/events/sample/foo_bar/filter
 # rmmod trace-events-sample.ko

[ Impact: fix memory leak when unloading module ]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A375A30.9060802@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      57be8887
    • S
      ring-buffer: use commit counters for commit pointer accounting · fa743953
      由 Steven Rostedt 提交于 
      The ring buffer is made up of three sets of pointers.

The head page pointer, which points to the next page for the reader to
get.

The commit pointer and commit index, which points to the page and index
of the last committed write respectively.

The tail pointer and tail index, which points to the page and the index
of the last reserved data respectively (non committed).

The commit pointer is only moved forward by the outer most writer.
If a nested writer comes in, it will not move the pointer forward.

The current implementation has a flaw. It assumes that the outer most
writer successfully reserved data. There's a small race window where
the outer most writer could find the tail pointer, but a nested
writer could come in (via interrupt) and move the tail forward, and
even the commit forward.

The outer writer would not realized the commit moved forward and the
accounting will break.

This patch changes the design to use counters in the per cpu buffers
to keep track of commits. The counters are incremented at the start
of the commit, and decremented at the end. If the end commit counter
is 1, then it moves the commit pointers. A loop is made to check for
races between checking and moving the commit pointers. Only the outer
commit should move the pointers anyway.

The test of knowing if a reserve is equal to the last commit update
is still needed to know for time keeping. The time code is much less
racey than the commit updates.

This change not only solves the mentioned race, but also makes the
code simpler.

[ Impact: fix commit race and simplify code ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      fa743953
    • S
      ring-buffer: remove unused variable · 263294f3
      由 Steven Rostedt 提交于 
      Fix the compiler error:

kernel/trace/ring_buffer.c: In function 'rb_move_tail':
kernel/trace/ring_buffer.c:1236: warning: unused variable 'event'
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      263294f3
    • S
      ring-buffer: have benchmark test handle discarded events · 9086c7b9
      由 Steven Rostedt 提交于 
      With the addition of commit:

  c7b09308
  ring-buffer: prevent adding write in discarded area

The ring buffer may now add discarded events when a write passes
the end of a buffer page. Before, a discarded event was only added
when the tracer deliberately created one. The ring buffer benchmark
test does not handle discarded events when it reads the buffer and
fails when it encounters one.

Also fix the increment for large data entries (luckily, the test did
not add any yet).

[ Impact: fix false failure of ring buffer self test ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      9086c7b9
  5. 15 6月, 2009 29 次提交