From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Currently there's no easy way to reset iterating over a trace.dat file if a
tracecmd_iterate_events() was called. Add a helper function to do that:
tracecmd_iterate_reset()
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
.../libtracecmd/libtracecmd-iterate.txt | 10 +++++-
Documentation/libtracecmd/libtracecmd.txt | 1 +
include/trace-cmd/trace-cmd.h | 2 ++
lib/trace-cmd/trace-input.c | 32 +++++++++++++++++++
4 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/Documentation/libtracecmd/libtracecmd-iterate.txt b/Documentation/libtracecmd/libtracecmd-iterate.txt
index 12c54b2ce1a0..dc053ccbbade 100644
--- a/Documentation/libtracecmd/libtracecmd-iterate.txt
+++ b/Documentation/libtracecmd/libtracecmd-iterate.txt
@@ -4,7 +4,7 @@ libtracecmd(3)
NAME
----
tracecmd_iterate_events, tracecmd_iterate_events_multi, tracecmd_follow_event,
-tracecmd_follow_missed_events, tracecmd_filter_add - Read events from a trace file
+tracecmd_follow_missed_events, tracecmd_filter_add, tracecmd_iterate_reset - Read events from a trace file
SYNOPSIS
--------
@@ -45,6 +45,7 @@ int *tracecmd_follow_missed_events*(struct tracecmd_input pass:[*]_handle_,
void pass:[*]_callback_data_);
struct tracecmd_filter pass:[*]*tracecmd_filter_add*(struct tracecmd_input *_handle_,
const char pass:[*]_filter_str_, bool _neg_);
+int *tracecmd_iterate_reset*(struct tracecmd_input pass:[*]_handle_);
--
DESCRIPTION
@@ -140,6 +141,10 @@ is defined by *tep_filter_add_filter_str(3)*. If _neg_ is true, then the events
that match the filter will be skipped, otherwise the events that match will execute
the _callback()_ function in the iterators.
+The *tracecmd_iterate_reset()* sets the _handle_ back to start at the beginning, so that
+the next call to *tracecmd_iterate_events()* starts back at the first event again, instead
+of continuing where it left off.
+
RETURN VALUE
------------
Both *tracecmd_iterate_events()*, *tracecmd_iterate_events_reverse()* and
@@ -147,6 +152,9 @@ Both *tracecmd_iterate_events()*, *tracecmd_iterate_events_reverse()* and
(handling the follow and filters appropriately). Or an error value, which can include
returning a non-zero result from the _callback()_ function.
+*tracecmd_iterate_reset()* returns 0 on success and -1 if an error occurred. Note,
+if -1 is returned, a partial reset may have also happened.
+
EXAMPLE
-------
[source,c]
diff --git a/Documentation/libtracecmd/libtracecmd.txt b/Documentation/libtracecmd/libtracecmd.txt
index bbe6cc78b575..52d4e5994c14 100644
--- a/Documentation/libtracecmd/libtracecmd.txt
+++ b/Documentation/libtracecmd/libtracecmd.txt
@@ -61,6 +61,7 @@ Iterating over events in a trace file:
void pass:[*]_callback_data_);
struct tracecmd_filter pass:[*]*tracecmd_filter_add*(struct tracecmd_input *_handle_,
const char pass:[*]_filter_str_, bool _neg_);
+ int *tracecmd_iterate_reset*(struct tracecmd_input pass:[*]_handle_);
Read tracing instances from a trace file:
int *tracecmd_buffer_instances*(struct tracecmd_input pass:[*]_handle_);
diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index e6527b7116c1..55a0c51845b0 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -72,6 +72,8 @@ int tracecmd_follow_missed_events(struct tracecmd_input *handle,
int, void *),
void *callback_data);
+int tracecmd_iterate_reset(struct tracecmd_input *handle);
+
int tracecmd_iterate_events(struct tracecmd_input *handle,
cpu_set_t *cpus, int cpu_size,
int (*callback)(struct tracecmd_input *handle,
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index bf070f057ed0..88bef83f4fe0 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -2113,6 +2113,38 @@ tracecmd_read_cpu_first(struct tracecmd_input *handle, int cpu)
return tracecmd_read_data(handle, cpu);
}
+/**
+ * tracecmd_iterate_reset - Set the handle to iterate from the beginning
+ * @handle: input handle for the trace.dat file
+ *
+ * This causes tracecmd_iterate_events*() to start from the beginning
+ * of the trace.dat file.
+ */
+int tracecmd_iterate_reset(struct tracecmd_input *handle)
+{
+ unsigned long long page_offset;
+ int cpu;
+ int ret = 0;
+ int r;
+
+ for (cpu = 0; cpu < handle->cpus; cpu++) {
+ page_offset = calc_page_offset(handle, handle->cpu_data[cpu].file_offset);
+
+ r = get_page(handle, cpu, page_offset);
+ if (r < 0) {
+ ret = -1;
+ continue; /* ?? */
+ }
+
+ /* If the page was already mapped, we need to reset it */
+ if (r)
+ update_page_info(handle, cpu);
+
+ free_next(handle, cpu);
+ }
+ return ret;
+}
+
/**
* tracecmd_read_cpu_last - get the last record in a CPU
* @handle: input handle for the trace.dat file
--
2.42.0
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