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Date: Tue, 10 Aug 2021 11:07:29 +0900 From: Masami Hiramatsu <mhiramat@...nel.org> To: Steven Rostedt <rostedt@...dmis.org> Cc: linux-kernel@...r.kernel.org, Tom Zanussi <zanussi@...nel.org>, Masami Hiramatsu <mhiramat@...nel.org> Subject: [PATCH v4 03/10] tracing/boot: Support multiple handlers for per-event histogram Support multiple handlers for per-event histogram in boot-time tracing. Since the histogram can register multiple same handler-actions with different parameters, this expands the syntax to support such cases. With this update, the 'onmax', 'onchange' and 'onmatch' handler subkeys under per-event histogram option will take a number subkeys optionally as below. (see [.N]) ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist { onmax|onchange[.N] { var = <VAR>; <ACTION> [= <PARAM>] } onmatch[.N] { event = <EVENT>; <ACTION> [= <PARAM>] } } The 'N' must be a digit (or digit started word). Thus user can add several handler-actions to the histogram, for example, ftrace.event.SOMEGROUP.SOMEEVENT.hist { keys = SOME_ID; lat = common_timestamp.usecs-$ts0 onmatch.1 { event = GROUP1.STARTEVENT1 trace = latency_event, SOME_ID, $lat } onmatch.2 { event = GROUP2.STARTEVENT2 trace = latency_event, SOME_ID, $lat } } Then, it can trace the elapsed time from GROUP1.STARTEVENT1 to SOMEGROUP.SOMEEVENT, and from GROUP2.STARTEVENT2 to SOMEGROUP.SOMEEVENT with SOME_ID key. Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org> --- kernel/trace/trace_boot.c | 43 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c index 3d0e51368f51..f024f27b3602 100644 --- a/kernel/trace/trace_boot.c +++ b/kernel/trace/trace_boot.c @@ -245,8 +245,9 @@ trace_boot_hist_add_array(struct xbc_node *hnode, char **bufp, } static int __init -trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp, - char *end, const char *param) +trace_boot_hist_add_one_handler(struct xbc_node *hnode, char **bufp, + char *end, const char *handler, + const char *param) { struct xbc_node *knode, *anode; const char *p; @@ -259,7 +260,7 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp, xbc_node_get_data(hnode), param); return -EINVAL; } - append_printf(bufp, end, ":%s(%s)", xbc_node_get_data(hnode), p); + append_printf(bufp, end, ":%s(%s)", handler, p); /* Compose 'action' parameter */ knode = xbc_node_find_child(hnode, "trace"); @@ -294,6 +295,32 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp, return 0; } +static int __init +trace_boot_hist_add_handlers(struct xbc_node *hnode, char **bufp, + char *end, const char *param) +{ + struct xbc_node *node; + const char *p, *handler; + int ret; + + handler = xbc_node_get_data(hnode); + + xbc_node_for_each_subkey(hnode, node) { + p = xbc_node_get_data(node); + if (!isdigit(p[0])) + continue; + /* All digit started node should be instances. */ + ret = trace_boot_hist_add_one_handler(node, bufp, end, handler, param); + if (ret < 0) + break; + } + + if (xbc_node_find_child(hnode, param)) + ret = trace_boot_hist_add_one_handler(hnode, bufp, end, handler, param); + + return ret; +} + /* * Histogram boottime tracing syntax. * @@ -305,8 +332,8 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp, * name = <HISTNAME> * var { <VAR> = <EXPR> ... } * pause|continue|clear - * onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] } - * onmatch { event = <EVENT>; <ACTION> [= <PARAM>] } + * onmax|onchange[.N] { var = <VAR>; <ACTION> [= <PARAM>] } + * onmatch[.N] { event = <EVENT>; <ACTION> [= <PARAM>] } * filter = <FILTER> * } * @@ -368,13 +395,13 @@ trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size) /* Histogram handler and actions */ node = xbc_node_find_child(hnode, "onmax"); - if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0) + if (node && trace_boot_hist_add_handlers(node, &buf, end, "var") < 0) return -EINVAL; node = xbc_node_find_child(hnode, "onchange"); - if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0) + if (node && trace_boot_hist_add_handlers(node, &buf, end, "var") < 0) return -EINVAL; node = xbc_node_find_child(hnode, "onmatch"); - if (node && trace_boot_hist_add_handler(node, &buf, end, "event") < 0) + if (node && trace_boot_hist_add_handlers(node, &buf, end, "event") < 0) return -EINVAL; p = xbc_node_find_value(hnode, "filter", NULL);
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