linux/kernel/trace/ring_buffer.c, branch mybooklive

ring-buffer: Move disabled check into preempt disable section

2010-04-01T22:58:08Z

commit 52fbe9cde7fdb5c6fac196d7ebd2d92d05ef3cd4 upstream. The ring buffer resizing and resetting relies on a schedule RCU action. The buffers are disabled, a synchronize_sched() is called and then the resize or reset takes place. But this only works if the disabling of the buffers are within the preempt disabled section, otherwise a window exists that the buffers can be written to while a reset or resize takes place. Reported-by: Li Zefan Signed-off-by: Lai Jiangshan LKML-Reference: <4B949E43.2010906@cn.fujitsu.com> Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

ring-buffer: Synchronize resizing buffer with reader lock

2009-11-04T05:04:20Z

We got a sudden panic when we reduced the size of the ringbuffer. We can reproduce the panic by the following steps: echo 1 > events/sched/enable cat trace_pipe > /dev/null & while ((1)) do echo 12000 > buffer_size_kb echo 512 > buffer_size_kb done (not more than 5 seconds, panic ...) Reported-by: KOSAKI Motohiro Signed-off-by: Lai Jiangshan LKML-Reference: <4AF01735.9060409@cn.fujitsu.com> Signed-off-by: Steven Rostedt

tracing: Remove cpu arg from the rb_time_stamp() function

2009-10-24T09:07:51Z

The cpu argument is not used inside the rb_time_stamp() function. Plus fix a typo. Signed-off-by: Jiri Olsa Signed-off-by: Steven Rostedt Cc: Frederic Weisbecker LKML-Reference: <20091023233647.118547500@goodmis.org> Signed-off-by: Ingo Molnar

tracing: Fix comment typo and documentation example

2009-10-24T09:07:50Z

Trivial patch to fix a documentation example and to fix a comment. Signed-off-by: Jiri Olsa Signed-off-by: Steven Rostedt Cc: Frederic Weisbecker LKML-Reference: <20091023233646.871719877@goodmis.org> Signed-off-by: Ingo Molnar

includecheck fix: kernel/trace, ring_buffer.c

2009-09-20T11:28:56Z

fix the following 'make includecheck' warning: kernel/trace/ring_buffer.c: trace.h is included more than once. Signed-off-by: Jaswinder Singh Rajput Cc: Steven Rostedt Cc: Ingo Molnar Cc: Sam Ravnborg LKML-Reference: <1247068617.4382.107.camel@ht.satnam>

ring-buffer: typecast cmpxchg to fix PowerPC warning

2009-09-14T13:41:57Z

The cmpxchg used by PowerPC does the following: ({ \ __typeof__(*(ptr)) _o_ = (o); \ __typeof__(*(ptr)) _n_ = (n); \ (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \ (unsigned long)_n_, sizeof(*(ptr))); \ }) This does a type check of *ptr to both o and n. Unfortunately, the code in ring-buffer.c assigns longs to pointers and pointers to longs and causes a warning on PowerPC: ring_buffer.c: In function 'rb_head_page_set': ring_buffer.c:704: warning: initialization makes pointer from integer without a cast ring_buffer.c:704: warning: initialization makes pointer from integer without a cast ring_buffer.c: In function 'rb_head_page_replace': ring_buffer.c:797: warning: initialization makes integer from pointer without a cast This patch adds the typecasts inside cmpxchg to annotate that a long is being cast to a pointer and a pointer is being casted to a long and this removes the PowerPC warnings. Reported-by: Stephen Rothwell Signed-off-by: Steven Rostedt

ring-buffer: consolidate interface of rb_buffer_peek()

2009-09-10T03:54:02Z

rb_buffer_peek() operates with struct ring_buffer_per_cpu *cpu_buffer only. Thus, instead of passing variables buffer and cpu it is better to use cpu_buffer directly. This also reduces the risk of races since cpu_buffer is not calculated twice. Signed-off-by: Robert Richter LKML-Reference: <1249045084-3028-1-git-send-email-robert.richter@amd.com> Signed-off-by: Steven Rostedt

ring-buffer: only enable ring_buffer_swap_cpu when needed

2009-09-04T23:42:22Z

Since the ability to swap the cpu buffers adds a small overhead to the recording of a trace, we only want to add it when needed. Only the irqsoff and preemptoff tracers use this feature, and both are not recommended for production kernels. This patch disables its use when neither irqsoff nor preemptoff is configured. Signed-off-by: Steven Rostedt

ring-buffer: check for swapped buffers in start of committing

2009-09-04T23:38:42Z

Because the irqsoff tracer can swap an internal CPU buffer, it is possible that a swap happens between the start of the write and before the committing bit is set (the committing bit will disable swapping). This patch adds a check for this and will fail the write if it detects it. Signed-off-by: Steven Rostedt

ring-buffer: disable all cpu buffers when one finds a problem

2009-09-04T15:46:25Z

Currently the way RB_WARN_ON works, is to disable either the current CPU buffer or all CPU buffers, depending on whether a ring_buffer or ring_buffer_per_cpu struct was passed into the macro. Most users of the RB_WARN_ON pass in the CPU buffer, so only the one CPU buffer gets disabled but the rest are still active. This may confuse users even though a warning is sent to the console. This patch changes the macro to disable the entire buffer even if the CPU buffer is passed in. Signed-off-by: Steven Rostedt