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Date: Fri, 27 May 2022 08:36:22 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Linyu Yuan <quic_linyyuan@...cinc.com>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>, <linux-kernel@...r.kernel.org>,
"Masami Hiramatsu" <mhiramat@...nel.org>,
Tom Zanussi <zanussi@...nel.org>
Subject: Re: [PATCH 1/2] tracing/probes: auto generate events name when
create a group of events
Hi Linyu,
On Wed, 25 May 2022 09:33:57 +0800
Linyu Yuan <quic_linyyuan@...cinc.com> wrote:
>
> On 5/25/2022 6:31 AM, Steven Rostedt wrote:
> > [ Adding Masami (kprobe maintainer) and Tom (dynamic event maintainer) ]
> >
> > On Sun, 1 May 2022 17:34:10 +0800
> > Linyu Yuan <quic_linyyuan@...cinc.com> wrote:
> >
> >> change traceprobe_parse_event_name() and return GRP/EVENT types,
> >> TP_ENAME_GROUP_EVENT means user input GRP/EVENT format,
> >> TP_ENAME_EVENT means user only input EVENT format,
> >> TP_ENAME_GROUP means user only input GRP/ format,
> >>
> >> it allow no event name input when create a group of events,
> >> and will auto generate event name according second argument.
> > Sorry, but I can't understand the above. Can you reword it, and perhaps
> > include an example of what this patch does.
>
> thanks, will try to update after Masai and Tom comment
>
> >
> > After reading the code, I guess you are trying to make it so that you can
> > leave out the event name and only have the group name, if you add the slash.
> >
> > echo 'p:group/ schedule' > kprobe_events
> >
> > And that will create a kprobe "schedule" event under the "group" system?
>
> that's right
Hmm, it is an interesting idea :)
Please update the patch description, and avoid explaining internal
implementation details. Those flag explanation should be commented
in the code.
(And Cc to me.)
Thank you,
>
> >
> > Also, for some reason, patch 2 of the series never came to me. But it is in
> > my LKML folder :-/
> >
> >> Signed-off-by: Linyu Yuan <quic_linyyuan@...cinc.com>
> >> ---
> >> Documentation/trace/kprobetrace.rst | 8 ++++----
> >> Documentation/trace/uprobetracer.rst | 8 ++++----
> >> kernel/trace/trace_dynevent.c | 2 +-
> >> kernel/trace/trace_eprobe.c | 19 +++++++++++--------
> >> kernel/trace/trace_kprobe.c | 18 +++++++++++-------
> >> kernel/trace/trace_probe.c | 9 ++++++++-
> >> kernel/trace/trace_probe.h | 4 ++++
> >> kernel/trace/trace_uprobe.c | 14 +++++++++-----
> >> 8 files changed, 52 insertions(+), 30 deletions(-)
> >>
> >> diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
> >> index b175d88..4274cc6 100644
> >> --- a/Documentation/trace/kprobetrace.rst
> >> +++ b/Documentation/trace/kprobetrace.rst
> >> @@ -28,10 +28,10 @@ Synopsis of kprobe_events
> >> -------------------------
> >> ::
> >>
> >> - p[:[GRP/]EVENT] [MOD:]SYM[+offs]|MEMADDR [FETCHARGS] : Set a probe
> >> - r[MAXACTIVE][:[GRP/]EVENT] [MOD:]SYM[+0] [FETCHARGS] : Set a return probe
> >> - p:[GRP/]EVENT] [MOD:]SYM[+0]%return [FETCHARGS] : Set a return probe
> >> - -:[GRP/]EVENT : Clear a probe
> >> + p[:[GRP/][EVENT]] [MOD:]SYM[+offs]|MEMADDR [FETCHARGS] : Set a probe
> >> + r[MAXACTIVE][:[GRP/][EVENT]] [MOD:]SYM[+0] [FETCHARGS] : Set a return probe
> >> + p[:[GRP/][EVENT]] [MOD:]SYM[+0]%return [FETCHARGS] : Set a return probe
> >> + -:[GRP/][EVENT] : Clear a probe
> >>
> >> GRP : Group name. If omitted, use "kprobes" for it.
> >> EVENT : Event name. If omitted, the event name is generated
> >> diff --git a/Documentation/trace/uprobetracer.rst b/Documentation/trace/uprobetracer.rst
> >> index a8e5938..3a1797d7 100644
> >> --- a/Documentation/trace/uprobetracer.rst
> >> +++ b/Documentation/trace/uprobetracer.rst
> >> @@ -26,10 +26,10 @@ Synopsis of uprobe_tracer
> >> -------------------------
> >> ::
> >>
> >> - p[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a uprobe
> >> - r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a return uprobe (uretprobe)
> >> - p[:[GRP/]EVENT] PATH:OFFSET%return [FETCHARGS] : Set a return uprobe (uretprobe)
> >> - -:[GRP/]EVENT : Clear uprobe or uretprobe event
> >> + p[:[GRP/][EVENT]] PATH:OFFSET [FETCHARGS] : Set a uprobe
> >> + r[:[GRP/][EVENT]] PATH:OFFSET [FETCHARGS] : Set a return uprobe (uretprobe)
> >> + p[:[GRP/][EVENT]] PATH:OFFSET%return [FETCHARGS] : Set a return uprobe (uretprobe)
> >> + -:[GRP/][EVENT] : Clear uprobe or uretprobe event
> >>
> >> GRP : Group name. If omitted, "uprobes" is the default value.
> >> EVENT : Event name. If omitted, the event name is generated based
> >> diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
> >> index e34e8182..033248d 100644
> >> --- a/kernel/trace/trace_dynevent.c
> >> +++ b/kernel/trace/trace_dynevent.c
> >> @@ -101,7 +101,7 @@ int dyn_event_release(const char *raw_command, struct dyn_event_operations *type
> >> event = p + 1;
> >> *p = '\0';
> >> }
> >> - if (event[0] == '\0') {
> >> + if (!system && event[0] == '\0') {
> >> ret = -EINVAL;
> >> goto out;
> >> }
> >> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> >> index 7d44785..b16e067 100644
> >> --- a/kernel/trace/trace_eprobe.c
> >> +++ b/kernel/trace/trace_eprobe.c
> >> @@ -125,6 +125,7 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
> >> * We match the following:
> >> * event only - match all eprobes with event name
> >> * system and event only - match all system/event probes
> >> + * system only - match all system probes
> >> *
> >> * The below has the above satisfied with more arguments:
> >> *
> >> @@ -143,7 +144,7 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
> >> return false;
> >>
> >> /* Must match the event name */
> >> - if (strcmp(trace_probe_name(&ep->tp), event) != 0)
> >> + if (event[0] != '\0' && strcmp(trace_probe_name(&ep->tp), event) != 0)
> >> return false;
> >>
> >> /* No arguments match all */
> >> @@ -848,7 +849,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
> >> {
> >> /*
> >> * Argument syntax:
> >> - * e[:[GRP/]ENAME] SYSTEM.EVENT [FETCHARGS]
> >> + * e[:[GRP/][ENAME]] SYSTEM.EVENT [FETCHARGS]
> >> * Fetch args:
> >> * <name>=$<field>[:TYPE]
> >> */
> >> @@ -858,6 +859,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
> >> struct trace_eprobe *ep = NULL;
> >> char buf1[MAX_EVENT_NAME_LEN];
> >> char buf2[MAX_EVENT_NAME_LEN];
> >> + char grp_buf[MAX_EVENT_NAME_LEN];
> >> int ret = 0;
> >> int i;
> >>
> >> @@ -866,14 +868,16 @@ static int __trace_eprobe_create(int argc, const char *argv[])
> >>
> >> trace_probe_log_init("event_probe", argc, argv);
> >>
> >> + ret = TP_ENAME_EMPTTY;
> > EMPTY is spelled wrong.
>
>
> sorry, will wait comment from maintainer of V1, will fix it in V2 if
> V1 is not reject.
>
>
> >> event = strchr(&argv[0][1], ':');
> >> if (event) {
> >> event++;
> >> - ret = traceprobe_parse_event_name(&event, &group, buf1,
> >> + ret = traceprobe_parse_event_name(&event, &group, grp_buf,
> >> event - argv[0]);
> >> - if (ret)
> >> + if (ret < 0)
> >> goto parse_error;
> >> - } else {
> >> + }
> > add space.
>
> sure, thanks.
>
> >
> >> + if (ret == TP_ENAME_EMPTTY || ret == TP_ENAME_GROUP) {
> >> strscpy(buf1, argv[1], MAX_EVENT_NAME_LEN);
> >> sanitize_event_name(buf1);
> >> event = buf1;
> > I'd like to see Masami's and Tom's comments on this one.
> >
> > -- Steve
> >
> >> @@ -882,9 +886,8 @@ static int __trace_eprobe_create(int argc, const char *argv[])
> >> goto parse_error;
> >>
> >> sys_event = argv[1];
> >> - ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2,
> >> - sys_event - argv[1]);
> >> - if (ret || !sys_name)
> >> + ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
> >> + if (ret != TP_ENAME_GROUP_EVENT)
> >> goto parse_error;
> >> if (!is_good_name(sys_event) || !is_good_name(sys_name))
> >> goto parse_error;
> >> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> >> index 47cebef..2cd8ef9 100644
> >> --- a/kernel/trace/trace_kprobe.c
> >> +++ b/kernel/trace/trace_kprobe.c
> >> @@ -163,7 +163,8 @@ static bool trace_kprobe_match(const char *system, const char *event,
> >> {
> >> struct trace_kprobe *tk = to_trace_kprobe(ev);
> >>
> >> - return strcmp(trace_probe_name(&tk->tp), event) == 0 &&
> >> + return (event[0] == '\0' ||
> >> + strcmp(trace_probe_name(&tk->tp), event) == 0) &&
> >> (!system || strcmp(trace_probe_group_name(&tk->tp), system) == 0) &&
> >> trace_kprobe_match_command_head(tk, argc, argv);
> >> }
> >> @@ -708,11 +709,11 @@ static int __trace_kprobe_create(int argc, const char *argv[])
> >> /*
> >> * Argument syntax:
> >> * - Add kprobe:
> >> - * p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
> >> + * p[:[GRP/][EVENT]] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
> >> * - Add kretprobe:
> >> - * r[MAXACTIVE][:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
> >> + * r[MAXACTIVE][:[GRP/][EVENT]] [MOD:]KSYM[+0] [FETCHARGS]
> >> * Or
> >> - * p:[GRP/]EVENT] [MOD:]KSYM[+0]%return [FETCHARGS]
> >> + * p[:[GRP/][EVENT]] [MOD:]KSYM[+0]%return [FETCHARGS]
> >> *
> >> * Fetch args:
> >> * $retval : fetch return value
> >> @@ -739,6 +740,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
> >> long offset = 0;
> >> void *addr = NULL;
> >> char buf[MAX_EVENT_NAME_LEN];
> >> + char grp_buf[MAX_EVENT_NAME_LEN];
> >> unsigned int flags = TPARG_FL_KERNEL;
> >>
> >> switch (argv[0][0]) {
> >> @@ -832,12 +834,14 @@ static int __trace_kprobe_create(int argc, const char *argv[])
> >> }
> >>
> >> trace_probe_log_set_index(0);
> >> + ret = TP_ENAME_EMPTTY;
> >> if (event) {
> >> - ret = traceprobe_parse_event_name(&event, &group, buf,
> >> + ret = traceprobe_parse_event_name(&event, &group, grp_buf,
> >> event - argv[0]);
> >> - if (ret)
> >> + if (ret < 0)
> >> goto parse_error;
> >> - } else {
> >> + }
> >> + if (ret == TP_ENAME_EMPTTY || ret == TP_ENAME_GROUP) {
> >> /* Make a new event name */
> >> if (symbol)
> >> snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
> >> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> >> index 80863c6..7fd50ab 100644
> >> --- a/kernel/trace/trace_probe.c
> >> +++ b/kernel/trace/trace_probe.c
> >> @@ -257,6 +257,9 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> >> }
> >> len = strlen(event);
> >> if (len == 0) {
> >> + if (slash)
> >> + return TP_ENAME_GROUP;
> >> +
> >> trace_probe_log_err(offset, NO_EVENT_NAME);
> >> return -EINVAL;
> >> } else if (len > MAX_EVENT_NAME_LEN) {
> >> @@ -267,7 +270,11 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> >> trace_probe_log_err(offset, BAD_EVENT_NAME);
> >> return -EINVAL;
> >> }
> >> - return 0;
> >> +
> >> + if (slash)
> >> + return TP_ENAME_GROUP_EVENT;
> >> +
> >> + return TP_ENAME_EVENT;
> >> }
> >>
> >> #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
> >> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> >> index 92cc149..d726769 100644
> >> --- a/kernel/trace/trace_probe.h
> >> +++ b/kernel/trace/trace_probe.h
> >> @@ -364,6 +364,10 @@ extern void traceprobe_free_probe_arg(struct probe_arg *arg);
> >> extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
> >> int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> >> char *buf, int offset);
> >> +#define TP_ENAME_GROUP_EVENT 0
> >> +#define TP_ENAME_EVENT 1
> >> +#define TP_ENAME_GROUP 2
> >> +#define TP_ENAME_EMPTTY 3
> >>
> >> enum probe_print_type {
> >> PROBE_PRINT_NORMAL,
> >> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> >> index 9711589..a935c08 100644
> >> --- a/kernel/trace/trace_uprobe.c
> >> +++ b/kernel/trace/trace_uprobe.c
> >> @@ -312,7 +312,8 @@ static bool trace_uprobe_match(const char *system, const char *event,
> >> {
> >> struct trace_uprobe *tu = to_trace_uprobe(ev);
> >>
> >> - return strcmp(trace_probe_name(&tu->tp), event) == 0 &&
> >> + return (event[0] == '\0' ||
> >> + strcmp(trace_probe_name(&tu->tp), event) == 0) &&
> >> (!system || strcmp(trace_probe_group_name(&tu->tp), system) == 0) &&
> >> trace_uprobe_match_command_head(tu, argc, argv);
> >> }
> >> @@ -532,7 +533,7 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
> >>
> >> /*
> >> * Argument syntax:
> >> - * - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET[%return][(REF)] [FETCHARGS]
> >> + * - Add uprobe: p|r[:[GRP/][EVENT]] PATH:OFFSET[%return][(REF)] [FETCHARGS]
> >> */
> >> static int __trace_uprobe_create(int argc, const char **argv)
> >> {
> >> @@ -540,6 +541,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
> >> const char *event = NULL, *group = UPROBE_EVENT_SYSTEM;
> >> char *arg, *filename, *rctr, *rctr_end, *tmp;
> >> char buf[MAX_EVENT_NAME_LEN];
> >> + char grp_buf[MAX_EVENT_NAME_LEN];
> >> enum probe_print_type ptype;
> >> struct path path;
> >> unsigned long offset, ref_ctr_offset;
> >> @@ -644,12 +646,14 @@ static int __trace_uprobe_create(int argc, const char **argv)
> >>
> >> /* setup a probe */
> >> trace_probe_log_set_index(0);
> >> + ret = TP_ENAME_EMPTTY;
> >> if (event) {
> >> - ret = traceprobe_parse_event_name(&event, &group, buf,
> >> + ret = traceprobe_parse_event_name(&event, &group, grp_buf,
> >> event - argv[0]);
> >> - if (ret)
> >> + if (ret < 0)
> >> goto fail_address_parse;
> >> - } else {
> >> + }
> >> + if (ret == TP_ENAME_EMPTTY || ret == TP_ENAME_GROUP) {
> >> char *tail;
> >> char *ptr;
> >>
--
Masami Hiramatsu (Google) <mhiramat@...nel.org>
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