From: Steven Rostedt <rostedt@goodmis.org>
To: linux-trace-devel@vger.kernel.org
Cc: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Subject: [PATCH 2/2] libtracefs synthetic: Handle hashed name variables
Date: Fri, 5 Jan 2024 00:21:01 -0500 [thread overview]
Message-ID: <20240105052141.228999-3-rostedt@goodmis.org> (raw)
In-Reply-To: <20240105052141.228999-1-rostedt@goodmis.org>
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
When running:
sqlhist -m delta -n 'wakeup' 'select start.pid, (end.TIMESTAMP_USECS - start.TIMESTAMP_USECS) as delta from sched_waking as start join sched_switch as end on start.pid = end.next_pid'
The '-m delta' is supposed to set the "onmax()" to the "delta" variable. But
this fails because the output would be:
echo 'hist:keys=next_pid:__pid_17298_1=$__arg_17298_2,__delta_17298_4=common_timestamp.usecs-$__arg_17298_3:onmax($delta).trace(wakeup,$__pid_17298_1,$__delta_17298_4)'
As the "delta" was hashed to __delta_17298_4 and the "onmax()" has "$delta"
unhashed. In actuality, it wouldn't even get that far as the "test_max_var()"
will flag it as the variable does not exist (because it's not "delta" but
"__delta_17298_4").
Modify test_max_var() to check for hashed variables and return the one it
found.
Fixe: 00c6b5f6 ("libtracefs: Use unique names for sql field variables")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
src/tracefs-hist.c | 80 ++++++++++++++++++++++++++++++++++++++++------
1 file changed, 70 insertions(+), 10 deletions(-)
diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
index 5f32ec305409..2b4f17f2f6ec 100644
--- a/src/tracefs-hist.c
+++ b/src/tracefs-hist.c
@@ -13,6 +13,7 @@
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
+#include <ctype.h>
#include <sys/time.h>
#include <sys/types.h>
@@ -1687,27 +1688,81 @@ int tracefs_synth_append_end_filter(struct tracefs_synth *synth,
type, field, compare, val);
}
-static int test_max_var(struct tracefs_synth *synth, const char *var)
+static bool var_match(const char *match, const char *var, int match_len, int len)
+{
+ char copy[match_len + 1];
+ char *p, *e;
+
+ strncpy(copy, match, match_len + 1);
+ copy[match_len] = '\0';
+
+ p = copy;
+
+ if (*p == '$')
+ p++;
+
+ if (strncmp(p, var, len) == 0)
+ return true;
+
+ /* Check if this was hashed __<var>_<number>_<number> */
+ if (p[0] != '_' || p[1] != '_')
+ return false;
+
+ p += 2;
+
+ e = copy + match_len - 1;
+ if (!isdigit(*e))
+ return false;
+ while (isdigit(*e) && e > p)
+ e--;
+ if (e == p || *e != '_')
+ return false;
+
+ e--;
+ if (!isdigit(*e))
+ return false;
+ while (isdigit(*e) && e > p)
+ e--;
+ if (e == p || *e != '_')
+ return false;
+
+ if (e - p != len)
+ return false;
+
+ *e = '\0';
+
+ return strncmp(p, var, len) == 0;
+}
+
+static char *test_max_var(struct tracefs_synth *synth, const char *var)
{
char **vars = synth->end_vars;
+ char *ret;
char *p;
int len;
int i;
len = strlen(var);
+ if (var[0] == '$') {
+ var++;
+ len--;
+ }
/* Make sure the var is defined for the end event */
for (i = 0; vars[i]; i++) {
p = strchr(vars[i], '=');
if (!p)
continue;
- if (p - vars[i] != len)
- continue;
- if (!strncmp(var, vars[i], len))
- return 0;
+
+ if (var_match(vars[i], var, p - vars[i], len)) {
+ i = asprintf(&ret, "%.*s", (int)(p - vars[i]), vars[i]);
+ if (i < 0)
+ return NULL;
+ return ret;
+ }
}
errno = ENODEV;
- return -1;
+ return NULL;
}
static struct action *create_action(enum tracefs_synth_handler type,
@@ -1715,14 +1770,16 @@ static struct action *create_action(enum tracefs_synth_handler type,
const char *var)
{
struct action *action;
+ char *newvar = NULL;
int ret;
switch (type) {
case TRACEFS_SYNTH_HANDLE_MAX:
case TRACEFS_SYNTH_HANDLE_CHANGE:
- ret = test_max_var(synth, var);
- if (ret < 0)
+ newvar = test_max_var(synth, var);
+ if (!newvar)
return NULL;
+ var = newvar;
break;
default:
break;
@@ -1730,15 +1787,18 @@ static struct action *create_action(enum tracefs_synth_handler type,
action = calloc(1, sizeof(*action));
if (!action)
- return NULL;
+ goto out;
if (var) {
ret = asprintf(&action->handle_field, "$%s", var);
- if (!action->handle_field) {
+ if (ret < 0) {
free(action);
+ free(newvar);
return NULL;
}
}
+ out:
+ free(newvar);
return action;
}
--
2.42.0
prev parent reply other threads:[~2024-01-05 5:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-05 5:20 [PATCH 0/2] libtracefs sql: A couple of fixes Steven Rostedt
2024-01-05 5:21 ` [PATCH 1/2] libtracefs synthetic: Remove multiple adding of action in tracefs_synth_save() Steven Rostedt
2024-01-05 5:21 ` Steven Rostedt [this message]
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