tracing/boot: Add per-event histogram action options
Add a hist-trigger action syntax support to boot-time tracing.
Currently, boot-time tracing supports per-event actions as option
strings. However, for the histogram action, it has a special syntax
and usually needs a long action definition.
To make it readable and fit to the bootconfig syntax, this introduces
a new options for histogram.
Here are the histogram action options for boot-time tracing.
ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {
keys = <KEY>[,...]
values = <VAL>[,...]
sort = <SORT-KEY>[,...]
size = <ENTRIES>
name = <HISTNAME>
var { <VAR> = <EXPR> ... }
pause|continue|clear
onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] }
onmatch { event = <EVENT>; <ACTION> [= <PARAM>] }
filter = <FILTER>
}
Where <ACTION> is one of below;
trace = <EVENT>, <ARG1>[, ...]
save = <ARG1>[, ...]
snapshot
Link: https://lkml.kernel.org/r/162856124106.203126.10501871028479029087.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu
Steven Rostedt (VMware)
parent
c3b1c377f0
commit
e66ed86ca6
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@ -171,6 +171,231 @@ trace_boot_add_synth_event(struct xbc_node *node, const char *event)
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}
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#endif
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#ifdef CONFIG_HIST_TRIGGERS
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static int __init __printf(3, 4)
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append_printf(char **bufp, char *end, const char *fmt, ...)
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{
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va_list args;
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int ret;
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if (*bufp == end)
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return -ENOSPC;
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va_start(args, fmt);
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ret = vsnprintf(*bufp, end - *bufp, fmt, args);
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if (ret < end - *bufp) {
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*bufp += ret;
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} else {
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*bufp = end;
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ret = -ERANGE;
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}
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va_end(args);
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return ret;
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}
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static int __init
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append_str_nospace(char **bufp, char *end, const char *str)
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{
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char *p = *bufp;
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int len;
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while (p < end - 1 && *str != '\0') {
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if (!isspace(*str))
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*(p++) = *str;
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str++;
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}
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*p = '\0';
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if (p == end - 1) {
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*bufp = end;
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return -ENOSPC;
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}
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len = p - *bufp;
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*bufp = p;
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return (int)len;
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}
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static int __init
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trace_boot_hist_add_array(struct xbc_node *hnode, char **bufp,
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char *end, const char *key)
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{
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struct xbc_node *knode, *anode;
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const char *p;
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char sep;
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knode = xbc_node_find_child(hnode, key);
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if (knode) {
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anode = xbc_node_get_child(knode);
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if (!anode) {
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pr_err("hist.%s requires value(s).\n", key);
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return -EINVAL;
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}
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append_printf(bufp, end, ":%s", key);
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sep = '=';
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xbc_array_for_each_value(anode, p) {
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append_printf(bufp, end, "%c%s", sep, p);
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if (sep == '=')
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sep = ',';
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}
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} else
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return -ENOENT;
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return 0;
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}
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static int __init
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trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
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char *end, const char *param)
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{
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struct xbc_node *knode, *anode;
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const char *p;
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char sep;
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/* Compose 'handler' parameter */
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p = xbc_node_find_value(hnode, param, NULL);
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if (!p) {
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pr_err("hist.%s requires '%s' option.\n",
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xbc_node_get_data(hnode), param);
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return -EINVAL;
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}
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append_printf(bufp, end, ":%s(%s)", xbc_node_get_data(hnode), p);
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/* Compose 'action' parameter */
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knode = xbc_node_find_child(hnode, "trace");
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if (!knode)
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knode = xbc_node_find_child(hnode, "save");
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if (knode) {
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anode = xbc_node_get_child(knode);
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if (!anode || !xbc_node_is_value(anode)) {
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pr_err("hist.%s.%s requires value(s).\n",
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xbc_node_get_data(hnode),
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xbc_node_get_data(knode));
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return -EINVAL;
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}
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append_printf(bufp, end, ".%s", xbc_node_get_data(knode));
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sep = '(';
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xbc_array_for_each_value(anode, p) {
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append_printf(bufp, end, "%c%s", sep, p);
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if (sep == '(')
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sep = ',';
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}
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append_printf(bufp, end, ")");
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} else if (xbc_node_find_child(hnode, "snapshot")) {
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append_printf(bufp, end, ".snapshot()");
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} else {
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pr_err("hist.%s requires an action.\n",
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xbc_node_get_data(hnode));
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return -EINVAL;
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}
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return 0;
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}
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/*
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* Histogram boottime tracing syntax.
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*
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* ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {
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* keys = <KEY>[,...]
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* values = <VAL>[,...]
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* sort = <SORT-KEY>[,...]
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* size = <ENTRIES>
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* name = <HISTNAME>
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* var { <VAR> = <EXPR> ... }
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* pause|continue|clear
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* onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] }
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* onmatch { event = <EVENT>; <ACTION> [= <PARAM>] }
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* filter = <FILTER>
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* }
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*
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* Where <ACTION> are;
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*
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* trace = <EVENT>, <ARG1>[, ...]
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* save = <ARG1>[, ...]
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* snapshot
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*/
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static int __init
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trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)
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{
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struct xbc_node *node, *knode;
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char *end = buf + size;
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const char *p;
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int ret = 0;
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append_printf(&buf, end, "hist");
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ret = trace_boot_hist_add_array(hnode, &buf, end, "keys");
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if (ret < 0) {
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if (ret == -ENOENT)
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pr_err("hist requires keys.\n");
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return -EINVAL;
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}
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ret = trace_boot_hist_add_array(hnode, &buf, end, "values");
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if (ret == -EINVAL)
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return ret;
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ret = trace_boot_hist_add_array(hnode, &buf, end, "sort");
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if (ret == -EINVAL)
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return ret;
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p = xbc_node_find_value(hnode, "size", NULL);
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if (p)
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append_printf(&buf, end, ":size=%s", p);
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p = xbc_node_find_value(hnode, "name", NULL);
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if (p)
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append_printf(&buf, end, ":name=%s", p);
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node = xbc_node_find_child(hnode, "var");
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if (node) {
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xbc_node_for_each_key_value(node, knode, p) {
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/* Expression must not include spaces. */
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append_printf(&buf, end, ":%s=",
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xbc_node_get_data(knode));
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append_str_nospace(&buf, end, p);
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}
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}
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/* Histogram control attributes (mutual exclusive) */
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if (xbc_node_find_child(hnode, "pause"))
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append_printf(&buf, end, ":pause");
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else if (xbc_node_find_child(hnode, "continue"))
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append_printf(&buf, end, ":continue");
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else if (xbc_node_find_child(hnode, "clear"))
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append_printf(&buf, end, ":clear");
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/* Histogram handler and actions */
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node = xbc_node_find_child(hnode, "onmax");
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if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
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return -EINVAL;
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node = xbc_node_find_child(hnode, "onchange");
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if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
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return -EINVAL;
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node = xbc_node_find_child(hnode, "onmatch");
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if (node && trace_boot_hist_add_handler(node, &buf, end, "event") < 0)
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return -EINVAL;
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p = xbc_node_find_value(hnode, "filter", NULL);
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if (p)
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append_printf(&buf, end, " if %s", p);
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if (buf == end) {
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pr_err("hist exceeds the max command length.\n");
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return -E2BIG;
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}
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return 0;
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}
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#else
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static int __init
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trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)
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{
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return -EOPNOTSUPP;
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}
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#endif
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static void __init
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trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
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struct xbc_node *enode)
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@ -212,6 +437,12 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
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else if (trigger_process_regex(file, buf) < 0)
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pr_err("Failed to apply an action: %s\n", buf);
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}
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anode = xbc_node_find_child(enode, "hist");
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if (anode &&
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trace_boot_compose_hist_cmd(anode, buf, ARRAY_SIZE(buf)) == 0) {
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if (trigger_process_regex(file, buf) < 0)
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pr_err("Failed to apply hist trigger: %s\n", buf);
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}
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} else if (xbc_node_find_value(enode, "actions", NULL))
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pr_err("Failed to apply event actions because CONFIG_HIST_TRIGGERS is not set.\n");
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