linux-kernel - [PATCH v1] perf pmu: Make parser reentrant

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Date:   Mon,  3 Apr 2023 10:20:31 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        James Clark <james.clark@....com>,
        Suzuki Poulouse <suzuki.poulose@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Rob Herring <robh@...nel.org>, Leo Yan <leo.yan@...aro.org>,
        German Gomez <german.gomez@....com>,
        Jing Zhang <renyu.zj@...ux.alibaba.com>,
        Gaosheng Cui <cuigaosheng1@...wei.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1] perf pmu: Make parser reentrant

By default bison uses global state for compatibility with yacc. Make
the parser reentrant so that it may be used in asynchronous and
multithreaded situations.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/pmu.c | 17 ++++++++++++-----
 tools/perf/util/pmu.h |  2 +-
 tools/perf/util/pmu.l | 17 ++++++++++++-----
 tools/perf/util/pmu.y |  5 ++++-
 4 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index e3aae731bd6f..8ef2532428a4 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -24,6 +24,8 @@
 #include "evsel.h"
 #include "pmu.h"
 #include "pmus.h"
+#include "pmu-bison.h"
+#include "pmu-flex.h"
 #include "parse-events.h"
 #include "print-events.h"
 #include "header.h"
@@ -57,9 +59,6 @@ struct perf_pmu_format {
 	struct list_head list;
 };
 
-int perf_pmu_parse(struct list_head *list, char *name);
-extern FILE *perf_pmu_in;
-
 static bool hybrid_scanned;
 
 /*
@@ -79,6 +78,7 @@ int perf_pmu__format_parse(char *dir, struct list_head *head)
 	while (!ret && (evt_ent = readdir(format_dir))) {
 		char path[PATH_MAX];
 		char *name = evt_ent->d_name;
+		void *scanner;
 		FILE *file;
 
 		if (!strcmp(name, ".") || !strcmp(name, ".."))
@@ -91,8 +91,15 @@ int perf_pmu__format_parse(char *dir, struct list_head *head)
 		if (!file)
 			break;
 
-		perf_pmu_in = file;
-		ret = perf_pmu_parse(head, name);
+		ret = perf_pmu_lex_init(&scanner);
+		if (ret) {
+			fclose(file);
+			break;
+		}
+
+		perf_pmu_set_in(file, scanner);
+		ret = perf_pmu_parse(head, name, scanner);
+		perf_pmu_lex_destroy(scanner);
 		fclose(file);
 	}
 
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 24cf69ab32cd..52c37081c880 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -206,7 +206,7 @@ int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
 			  struct perf_pmu_info *info);
 struct list_head *perf_pmu__alias(struct perf_pmu *pmu,
 				  struct list_head *head_terms);
-void perf_pmu_error(struct list_head *list, char *name, char const *msg);
+void perf_pmu_error(struct list_head *list, char *name, void *scanner, char const *msg);
 
 int perf_pmu__new_format(struct list_head *list, char *name,
 			 int config, unsigned long *bits);
diff --git a/tools/perf/util/pmu.l b/tools/perf/util/pmu.l
index 58b4926cfaca..67b247be693b 100644
--- a/tools/perf/util/pmu.l
+++ b/tools/perf/util/pmu.l
@@ -1,4 +1,6 @@
 %option prefix="perf_pmu_"
+%option reentrant
+%option bison-bridge
 
 %{
 #include <stdlib.h>
@@ -6,16 +8,21 @@
 #include "pmu.h"
 #include "pmu-bison.h"
 
-static int value(int base)
+char *perf_pmu_get_text(yyscan_t yyscanner);
+YYSTYPE *perf_pmu_get_lval(yyscan_t yyscanner);
+
+static int value(yyscan_t scanner, int base)
 {
+	YYSTYPE *yylval = perf_pmu_get_lval(scanner);
+	char *text = perf_pmu_get_text(scanner);
 	long num;
 
 	errno = 0;
-	num = strtoul(perf_pmu_text, NULL, base);
+	num = strtoul(text, NULL, base);
 	if (errno)
 		return PP_ERROR;
 
-	perf_pmu_lval.num = num;
+	yylval->num = num;
 	return PP_VALUE;
 }
 
@@ -25,7 +32,7 @@ num_dec         [0-9]+
 
 %%
 
-{num_dec}	{ return value(10); }
+{num_dec}	{ return value(yyscanner, 10); }
 config		{ return PP_CONFIG; }
 -		{ return '-'; }
 :		{ return ':'; }
@@ -35,7 +42,7 @@ config		{ return PP_CONFIG; }
 
 %%
 
-int perf_pmu_wrap(void)
+int perf_pmu_wrap(void *scanner __maybe_unused)
 {
 	return 1;
 }
diff --git a/tools/perf/util/pmu.y b/tools/perf/util/pmu.y
index e675d79a0274..dff4e892ac4d 100644
--- a/tools/perf/util/pmu.y
+++ b/tools/perf/util/pmu.y
@@ -1,6 +1,8 @@
-
+%define api.pure full
 %parse-param {struct list_head *format}
 %parse-param {char *name}
+%parse-param {void *scanner}
+%lex-param {void* scanner}
 
 %{
 
@@ -78,6 +80,7 @@ PP_VALUE
 
 void perf_pmu_error(struct list_head *list __maybe_unused,
 		    char *name __maybe_unused,
+		    void *scanner __maybe_unused,
 		    char const *msg __maybe_unused)
 {
 }
-- 
2.40.0.348.gf938b09366-goog