From 5685e0ff45f5df67e79e9b052b6ffd501ff38c11 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 7 Aug 2012 15:20:39 +0200 Subject: [PATCH] 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 Acked-by: Frederic Weisbecker Cc: "Frank Ch. Eigler" Cc: Arun Sharma Cc: Benjamin Redelings Cc: Corey Ashford Cc: Cyrill Gorcunov Cc: Frank Ch. Eigler Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Robert Richter Cc: Stephane Eranian Cc: Tom Zanussi Cc: Ulrich Drepper Link: http://lkml.kernel.org/r/1344345647-11536-5-git-send-email-jolsa@redhat.com Signed-off-by: Arnaldo Carvalho de Melo --- include/linux/perf_event.h | 2 ++ kernel/events/internal.h | 4 ++++ kernel/events/ring_buffer.c | 6 ++++++ 3 files changed, 12 insertions(+) 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); -- 2.30.2