[PATCH stable 6.1 0/3] perf build fixes

[PATCH stable 6.1 0/3] perf build fixes

[Florian Fainelli]

This patch series contains "perf" build fixes specific to 6.1. We have
seen occasional build failures in our CI looking like these:

util/parse-events-bison.c: In function 'yy_symbol_print':
util/parse-events-bison.c:901: error: unterminated #if
  901 | #if YYDEBUG
      |
util/parse-events-bison.c:1020:62: error: '_p' undeclared (first use in this function)
 1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
      |                                                              ^~
util/parse-events-bison.c:1020:62: note: each undeclared identifier is reported only once for each function it appears in
util/parse-events-bison.c:1020:64: error: expected ')' at end of input
 1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
      |                         ~                                      ^
      |                                                                )
 1021 |   YYFPRINTF (yyo, ")");
      |
util/parse-events-bison.c:1020:3: error: too few arguments to function 'yy_symbol_value_print'
 1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
      |   ^~~~~~~~~~~~~~~~~~~~~
util/parse-events-bison.c:991:1: note: declared here
  991 | yy_symbol_value_print (FILE *yyo,
      | ^~~~~~~~~~~~~~~~~~~~~

which are resolved by these patches.

Ian Rogers (3):
  perf build: Conditionally define NDEBUG
  perf parse-events: Make YYDEBUG dependent on doing a debug build
  perf build: Disable fewer bison warnings

 tools/perf/Makefile.config     |  1 +
 tools/perf/util/Build          | 12 ++++++++----
 tools/perf/util/expr.y         |  4 +++-
 tools/perf/util/parse-events.y |  3 +++
 tools/perf/util/pmu.y          |  3 +++
 5 files changed, 18 insertions(+), 5 deletions(-)

-- 
2.34.1

[PATCH stable 6.1 1/3] perf build: Conditionally define NDEBUG

[Florian Fainelli]

From: Ian Rogers <irogers@google.com>

commit 616b14b47a86d880ba21a363440f20f82152d8f2 upstream

When a build is done without DEBUG=1 then define NDEBUG. This will
compile out asserts and other debug code.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20230330183827.1412303-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 tools/perf/Makefile.config | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 249f3d841563..c54692976001 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -228,6 +228,7 @@ ifndef DEBUG
 endif
 
 ifeq ($(DEBUG),0)
+CORE_CFLAGS += -DNDEBUG=1
 ifeq ($(CC_NO_CLANG), 0)
   CORE_CFLAGS += -O3
 else
-- 
2.34.1

Re: [PATCH stable 6.1 1/3] perf build: Conditionally define NDEBUG

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:
- [Medium] Defining NDEBUG removes the side-effecting `bfd_check_format()` call inside `assert()`, leaving the `bfd` object uninitialized.
- [Medium] Compiling out assert() removes critical runtime validation, leading to deadlocks and NULL pointer dereferences.
- [Low] Defining NDEBUG causes variables only used in assert() to trigger unused-but-set build failures.
--

commit 34a3ad3c8a3c7ed93c69e4b84492292fae1cb400
Author: Ian Rogers <irogers@google.com>

perf build: Conditionally define NDEBUG

When a build is done without DEBUG=1 then define NDEBUG. This will
compile out asserts and other debug code.

Link: https://lore.kernel.org/r/20230330183827.1412303-1-irogers@google.com

> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 898226ea8cadc..45708084fd3d6 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -228,6 +228,7 @@ ifndef DEBUG
>  endif
>  
>  ifeq ($(DEBUG),0)
> +CORE_CFLAGS += -DNDEBUG=1

[Severity: Medium]
Will this cause a regression in tools/perf/util/annotate.c? The function
bfd_check_format() is called directly inside an assert() macro there. 

Since this function has side effects (identifying the binary format and
initializing the architecture and machine state), compiling it out will leave
the bfd structure uninitialized. 

Subsequent calls like bfd_get_arch(bfdf) operate on uninitialized bfdf state,
leading to NULL pointer dereferences and crashes during perf annotate.

[Severity: Low]
Will this also cause build regressions due to unused variables? Variables such
as old in tools/perf/util/block-range.c are initialized and assigned values but
are only read inside assert() macros. 

Compiling out assert() leaves these variables assigned but never read, which
triggers unused-but-set build failures because the perf build uses -Werror.

[Severity: Medium]
Does compiling out assert() remove required runtime validation elsewhere? The
codebase currently relies on assert() for handling expected runtime failures.

For example, in bench_sched_pipe() (tools/perf/bench/sched-pipe.c),
assert(pid >= 0) checks for fork() failures. Without it, a fork failure causes
the parent to execute the child's logic, reading from an empty pipe and
deadlocking indefinitely.

Similarly, in tools/perf/builtin-timechart.c (assert(cursor != NULL)) and
tools/perf/builtin-top.c (evlist__id2evsel), allocation and lookup failures
proceed without aborting, leading to immediate NULL pointer dereferences on
subsequent lines.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260519185154.2987285-1-florian.fainelli@broadcom.com?part=1

[PATCH stable 6.1 2/3] perf parse-events: Make YYDEBUG dependent on doing a debug build

[Florian Fainelli]

From: Ian Rogers <irogers@google.com>

commit d4ce60190e08d84f88937019defa5e3d23409ac1 upstream

YYDEBUG enables line numbers and other error helpers in the generated
parse-events-bison.c. These shouldn't be generated when debugging
isn't enabled.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rob Herring <robh@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230911170559.4037734-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 tools/perf/util/parse-events.y | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index be8c51770051..dbc350a2c382 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -6,7 +6,9 @@
 
 %{
 
+#ifndef NDEBUG
 #define YYDEBUG 1
+#endif
 
 #include <fnmatch.h>
 #include <stdio.h>
-- 
2.34.1

[PATCH stable 6.1 3/3] perf build: Disable fewer bison warnings

[Florian Fainelli]

From: Ian Rogers <irogers@google.com>

commit ddc8e4c966923ad1137790817157c8a5f0301aec upstream

If bison is version 3.8.2, reduce the number of bison C warnings
disabled. Earlier bison versions have all C warnings disabled. Avoid
implicit declarations of yylex by adding the declaration in the C
file. A header can't be included as a circular dependency would occur
due to the lexer using the bison defined tokens.

Committer notes:

Some recent versions of gcc and clang (noticed on Alpine Linux 3.17,
edge, clearlinux, fedora 37, etc.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Tom Rix <trix@redhat.com>
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20230728064917.767761-6-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
[florian: Remove non-existent tools/perf/util/bpf-filter.y in 6.1.y,
adjusted perf_pmu_lex() signature]
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 tools/perf/util/Build          | 12 ++++++++----
 tools/perf/util/expr.y         |  4 +++-
 tools/perf/util/parse-events.y |  1 +
 tools/perf/util/pmu.y          |  3 +++
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 2c364a9087a2..036f9780b398 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -269,10 +269,14 @@ CFLAGS_parse-events-flex.o  += $(flex_flags)
 CFLAGS_pmu-flex.o           += $(flex_flags)
 CFLAGS_expr-flex.o          += $(flex_flags)
 
-bison_flags := -DYYENABLE_NLS=0
-BISON_GE_35 := $(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\)/\1\2/g') \>\= 35)
-ifeq ($(BISON_GE_35),1)
-  bison_flags += -Wno-unused-parameter -Wno-nested-externs -Wno-implicit-function-declaration -Wno-switch-enum -Wno-unused-but-set-variable -Wno-unknown-warning-option
+# Some newer clang and gcc version complain about this
+# util/parse-events-bison.c:1317:9: error: variable 'parse_events_nerrs' set but not used [-Werror,-Wunused-but-set-variable]
+#  int yynerrs = 0;
+
+bison_flags := -DYYENABLE_NLS=0 -Wno-unused-but-set-variable
+BISON_GE_382 := $(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/\1\2\3/g') \>\= 382)
+ifeq ($(BISON_GE_382),1)
+  bison_flags += -Wno-switch-enum
 else
   bison_flags += -w
 endif
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index 635e562350c5..b8745d564b78 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -7,6 +7,8 @@
 #include "util/debug.h"
 #define IN_EXPR_Y 1
 #include "expr.h"
+#include "expr-bison.h"
+int expr_lex(YYSTYPE * yylval_param , void *yyscanner);
 %}
 
 %define api.pure full
@@ -56,7 +58,7 @@
 static void expr_error(double *final_val __maybe_unused,
 		       struct expr_parse_ctx *ctx __maybe_unused,
 		       bool compute_ids __maybe_unused,
-		       void *scanner,
+		       void *scanner __maybe_unused,
 		       const char *s)
 {
 	pr_debug("%s\n", s);
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index dbc350a2c382..42d4414760e3 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -20,6 +20,7 @@
 #include "parse-events.h"
 #include "parse-events-bison.h"
 
+int parse_events_lex(YYSTYPE * yylval_param, YYLTYPE * yylloc_param , void *yyscanner);
 void parse_events_error(YYLTYPE *loc, void *parse_state, void *scanner, char const *msg);
 
 #define ABORT_ON(val) \
diff --git a/tools/perf/util/pmu.y b/tools/perf/util/pmu.y
index e675d79a0274..ae88d2d2dd6a 100644
--- a/tools/perf/util/pmu.y
+++ b/tools/perf/util/pmu.y
@@ -9,6 +9,9 @@
 #include <linux/bitmap.h>
 #include <string.h>
 #include "pmu.h"
+#include "pmu-bison.h"
+
+int perf_pmu_lex(void);
 
 #define ABORT_ON(val) \
 do { \
-- 
2.34.1

Re: [PATCH stable 6.1 3/3] perf build: Disable fewer bison warnings

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The updated `sed` regex for parsing the bison version strictly requires three numeric components, causing a shell syntax error for two-component versions.
--

commit e696603d6c95e1ec405be3442c49513276f5ee86
Author: Ian Rogers <irogers@google.com>

perf build: Disable fewer bison warnings

This commit reduces the number of disabled bison C warnings for bison versions
3.8.2 and later. It also avoids implicit declarations of yylex by adding
declarations directly in the C files.

Link: https://lore.kernel.org/r/20230728064917.767761-6-irogers@google.com

> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index e315ecaec3233..b65ce3563bedd 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -269,10 +269,14 @@ CFLAGS_parse-events-flex.o  += $(flex_flags)
>  CFLAGS_pmu-flex.o           += $(flex_flags)
>  CFLAGS_expr-flex.o          += $(flex_flags)
>  
> -bison_flags := -DYYENABLE_NLS=0
> -BISON_GE_35 := $(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\)/\1\2/g') \>\= 35)
> -ifeq ($(BISON_GE_35),1)
> -  bison_flags += -Wno-unused-parameter -Wno-nested-externs -Wno-implicit-function-declaration -Wno-switch-enum -Wno-unused-but-set-variable -Wno-unknown-warning-option
> +# Some newer clang and gcc version complain about this
> +# util/parse-events-bison.c:1317:9: error: variable 'parse_events_nerrs' set but not used [-Werror,-Wunused-but-set-variable]
> +#  int yynerrs = 0;
> +
> +bison_flags := -DYYENABLE_NLS=0 -Wno-unused-but-set-variable
> +BISON_GE_382 := $(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/\1\2\3/g') \>\= 382)

[Severity: Low]
Will this new regex cause shell syntax errors for two-component version
strings like "bison (GNU Bison) 3.8"?

If the sed pattern strictly requires three numeric components, it will
fail to match a two-component string and output the unmodified string
instead.

When make passes this raw string containing unescaped parentheses
to expr, it will cause the shell to abort with a syntax error like
'sh: Syntax error: "(" unexpected' and fail the version check.

> +ifeq ($(BISON_GE_382),1)
> +  bison_flags += -Wno-switch-enum
>  else
>    bison_flags += -w
>  endif

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260519185154.2987285-1-florian.fainelli@broadcom.com?part=3

Re: [PATCH stable 6.1 0/3] perf build fixes

[Ian Rogers]

On Tue, May 19, 2026 at 11:51 AM Florian Fainelli
<florian.fainelli@broadcom.com> wrote:
>
> This patch series contains "perf" build fixes specific to 6.1. We have
> seen occasional build failures in our CI looking like these:
>
> util/parse-events-bison.c: In function 'yy_symbol_print':
> util/parse-events-bison.c:901: error: unterminated #if
>   901 | #if YYDEBUG
>       |
> util/parse-events-bison.c:1020:62: error: '_p' undeclared (first use in this function)
>  1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
>       |                                                              ^~
> util/parse-events-bison.c:1020:62: note: each undeclared identifier is reported only once for each function it appears in
> util/parse-events-bison.c:1020:64: error: expected ')' at end of input
>  1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
>       |                         ~                                      ^
>       |                                                                )
>  1021 |   YYFPRINTF (yyo, ")");
>       |
> util/parse-events-bison.c:1020:3: error: too few arguments to function 'yy_symbol_value_print'
>  1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
>       |   ^~~~~~~~~~~~~~~~~~~~~
> util/parse-events-bison.c:991:1: note: declared here
>   991 | yy_symbol_value_print (FILE *yyo,
>       | ^~~~~~~~~~~~~~~~~~~~~
>
> which are resolved by these patches.

Lgtm, but the changes should be unnecessary as perf from Linux 7.1
should run on Linux 6.1 and with more and better features.

Thanks,
Ian

> Ian Rogers (3):
>   perf build: Conditionally define NDEBUG
>   perf parse-events: Make YYDEBUG dependent on doing a debug build
>   perf build: Disable fewer bison warnings
>
>  tools/perf/Makefile.config     |  1 +
>  tools/perf/util/Build          | 12 ++++++++----
>  tools/perf/util/expr.y         |  4 +++-
>  tools/perf/util/parse-events.y |  3 +++
>  tools/perf/util/pmu.y          |  3 +++
>  5 files changed, 18 insertions(+), 5 deletions(-)
>
> --
> 2.34.1
>

Re: [PATCH stable 6.1 0/3] perf build fixes

[Florian Fainelli]

On 5/19/26 11:55, Ian Rogers wrote:
> On Tue, May 19, 2026 at 11:51 AM Florian Fainelli
> <florian.fainelli@broadcom.com> wrote:
>>
>> This patch series contains "perf" build fixes specific to 6.1. We have
>> seen occasional build failures in our CI looking like these:
>>
>> util/parse-events-bison.c: In function 'yy_symbol_print':
>> util/parse-events-bison.c:901: error: unterminated #if
>>    901 | #if YYDEBUG
>>        |
>> util/parse-events-bison.c:1020:62: error: '_p' undeclared (first use in this function)
>>   1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
>>        |                                                              ^~
>> util/parse-events-bison.c:1020:62: note: each undeclared identifier is reported only once for each function it appears in
>> util/parse-events-bison.c:1020:64: error: expected ')' at end of input
>>   1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
>>        |                         ~                                      ^
>>        |                                                                )
>>   1021 |   YYFPRINTF (yyo, ")");
>>        |
>> util/parse-events-bison.c:1020:3: error: too few arguments to function 'yy_symbol_value_print'
>>   1020 |   yy_symbol_value_print (yyo, yykind, yyvaluep, yylocationp, _parse_state, scanner);
>>        |   ^~~~~~~~~~~~~~~~~~~~~
>> util/parse-events-bison.c:991:1: note: declared here
>>    991 | yy_symbol_value_print (FILE *yyo,
>>        | ^~~~~~~~~~~~~~~~~~~~~
>>
>> which are resolved by these patches.
> 
> Lgtm, but the changes should be unnecessary as perf from Linux 7.1
> should run on Linux 6.1 and with more and better features.

That's a bit harder to ship logistically for us and likely for others as 
well where we expect a single source to build the kernel and its 
companion tools.
-- 
Florian

Re: [PATCH stable 6.1 0/3] perf build fixes

[Sasha Levin]

> This patch series contains "perf" build fixes specific to 6.1. We have
> seen occasional build failures in our CI looking like these:
[...]
> Ian Rogers (3):
>   perf build: Conditionally define NDEBUG
>   perf parse-events: Make YYDEBUG dependent on doing a debug build
>   perf build: Disable fewer bison warnings

Thanks for the series.

Patch 3/3 (ddc8e4c96692) has an upstream Fixes: follow-up,
878460e8d0ff8 ("perf build: Remove -Wno-unused-but-set-variable from
the flex flags when building with clang < 13.0.0"), which we need on
6.1 alongside 3/3 to keep clang<13 perf builds working. Without it,
3/3 unconditionally adds -Wno-unused-but-set-variable and drops the
-Wno-unknown-warning-option guard that was previously gated by
BISON_GE_35, so clang 11/12 fails under WERROR=1.

878460e8d0ff8 does not cherry-pick cleanly onto 6.1 - it references
the 'version-lt3' make macro (introduced by a9b451509565d, not in 6.1)
and bpf-filter-flex.o (no such file in 6.1's tools/perf). I wasn't
comfortable resolving that conflict blind on a 6.1-only perf change.

Could you send a v2 6.1 series that includes 878460e8d0ff8 adapted to
6.1 (or an equivalent 6.1-specific patch that preserves the
-Wno-unknown-warning-option guard for clang<13)? I'll queue the whole
thing once that piece is in.

--
Thanks,
Sasha