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Subject[PATCH v3] trace:Add "gfp_t" support in synthetic_events
Date
Add "gfp_t" support in synthetic_events, then the "gfp_t" type
parameter in some functions can be traced.

Prints the gfp flags as hex in addition to the human-readable flag
string. Example output:

whoopsie-630 [000] ...1 78.969452: testevent: bar=b20 (GFP_ATOMIC|__GFP_ZERO)
rcuc/0-11 [000] ...1 81.097555: testevent: bar=a20 (GFP_ATOMIC)
rcuc/0-11 [000] ...1 81.583123: testevent: bar=a20 (GFP_ATOMIC)

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Zhengjun Xing <zhengjun.xing@linux.intel.com>
---
kernel/trace/trace_events_hist.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index ca6b0dff60c5..30f0f32aca62 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -13,6 +13,10 @@
#include <linux/rculist.h>
#include <linux/tracefs.h>

+/* for gfp flag names */
+#include <linux/trace_events.h>
+#include <trace/events/mmflags.h>
+
#include "tracing_map.h"
#include "trace.h"
#include "trace_dynevent.h"
@@ -752,6 +756,8 @@ static int synth_field_size(char *type)
size = sizeof(unsigned long);
else if (strcmp(type, "pid_t") == 0)
size = sizeof(pid_t);
+ else if (strcmp(type, "gfp_t") == 0)
+ size = sizeof(gfp_t);
else if (synth_field_is_string(type))
size = synth_field_string_size(type);

@@ -792,6 +798,8 @@ static const char *synth_field_fmt(char *type)
fmt = "%lu";
else if (strcmp(type, "pid_t") == 0)
fmt = "%d";
+ else if (strcmp(type, "gfp_t") == 0)
+ fmt = "%x";
else if (synth_field_is_string(type))
fmt = "%s";

@@ -834,9 +842,20 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
i == se->n_fields - 1 ? "" : " ");
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
} else {
+ struct trace_print_flags __flags[] = {
+ __def_gfpflag_names, {-1, NULL} };
+
trace_seq_printf(s, print_fmt, se->fields[i]->name,
entry->fields[n_u64],
i == se->n_fields - 1 ? "" : " ");
+
+ if (strcmp(se->fields[i]->type, "gfp_t") == 0) {
+ trace_seq_puts(s, " (");
+ trace_print_flags_seq(s, "|",
+ entry->fields[n_u64],
+ __flags);
+ trace_seq_putc(s, ')');
+ }
n_u64++;
}
}
--
2.14.1
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