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authorJiri Olsa <jolsa@redhat.com>2012-08-07 15:20:39 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2012-08-10 12:16:22 -0300
commit5685e0ff45f5df67e79e9b052b6ffd501ff38c11 (patch)
treeead6bd92a49b42ec0ca5bfee467e03e37656a6f1
parent91d7753a45f8525dc75b6be01e427dc1c378dc16 (diff)
perf: Add perf_output_skip function to skip bytes in sample
Introducing perf_output_skip function to be able to skip data within the perf ring buffer. When writing data into perf ring buffer we first reserve needed place in ring buffer and then copy the actual data. There's a possibility we won't be able to fill all the reserved size with data, so we need a way to skip the remaining bytes. This is going to be useful when storing the user stack dump, where we might end up with less data than we originally requested. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: "Frank Ch. Eigler" <fche@redhat.com> Cc: Arun Sharma <asharma@fb.com> Cc: Benjamin Redelings <benjamin.redelings@nescent.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Frank Ch. Eigler <fche@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Stephane Eranian <eranian@google.com> Cc: Tom Zanussi <tzanussi@gmail.com> Cc: Ulrich Drepper <drepper@gmail.com> Link: http://lkml.kernel.org/r/1344345647-11536-5-git-send-email-jolsa@redhat.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r--include/linux/perf_event.h2
-rw-r--r--kernel/events/internal.h4
-rw-r--r--kernel/events/ring_buffer.c6
3 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index d41394a1af36..8a73f75beb16 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1321,6 +1321,8 @@ extern int perf_output_begin(struct perf_output_handle *handle,
extern void perf_output_end(struct perf_output_handle *handle);
extern unsigned int perf_output_copy(struct perf_output_handle *handle,
const void *buf, unsigned int len);
+extern unsigned int perf_output_skip(struct perf_output_handle *handle,
+ unsigned int len);
extern int perf_swevent_get_recursion_context(void);
extern void perf_swevent_put_recursion_context(int rctx);
extern void perf_event_enable(struct perf_event *event);
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 7fd5408493d2..ce7bdfc1d045 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -114,6 +114,10 @@ static inline int memcpy_common(void *dst, const void *src, size_t n)
DEFINE_OUTPUT_COPY(__output_copy, memcpy_common)
+#define MEMCPY_SKIP(dst, src, n) (n)
+
+DEFINE_OUTPUT_COPY(__output_skip, MEMCPY_SKIP)
+
#ifndef arch_perf_out_copy_user
#define arch_perf_out_copy_user __copy_from_user_inatomic
#endif
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index b4c2ad3dee7a..23cb34ff3973 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -188,6 +188,12 @@ unsigned int perf_output_copy(struct perf_output_handle *handle,
return __output_copy(handle, buf, len);
}
+unsigned int perf_output_skip(struct perf_output_handle *handle,
+ unsigned int len)
+{
+ return __output_skip(handle, NULL, len);
+}
+
void perf_output_end(struct perf_output_handle *handle)
{
perf_output_put_handle(handle);