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* [PATCH v3] tools lib: Fix builds when glibc contains strlcpy
@ 2019-12-24 17:20 Vitaly Chikunov
  2020-01-10 17:53 ` [tip: perf/core] tools lib: Fix builds when glibc contains strlcpy() tip-bot2 for Vitaly Chikunov
  0 siblings, 1 reply; 2+ messages in thread
From: Vitaly Chikunov @ 2019-12-24 17:20 UTC (permalink / raw)
  To: Arnaldo Carvalho de Melo, Arnaldo Carvalho de Melo,
	Peter Zijlstra, Ingo Molnar, linux-kernel
  Cc: Vitaly Chikunov, Dmitry V . Levin, Josh Poimboeuf, Vineet Gupta,
	stable, kbuild test robot

Disable a couple of compilation warning (which are treated as errors) on
strlcpy definition and declaration, allow users to compile perf and
kernel (objtool).

1. When glibc have strlcpy (such as in ALT Linux since 2004) objtool and
perf build fails with this (in gcc):

  In file included from exec-cmd.c:3:
  tools/include/linux/string.h:20:15: error: redundant redeclaration of ‘strlcpy’ [-Werror=redundant-decls]
     20 | extern size_t strlcpy(char *dest, const char *src, size_t size);

2. Clang ignores `-Wredundant-decls', but produces another warning when
building perf:

    CC       util/string.o
  ../lib/string.c:99:8: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
  size_t __weak strlcpy(char *dest, const char *src, size_t size)
  ../../tools/include/linux/compiler.h:66:34: note: expanded from macro '__weak'
  # define __weak                 __attribute__((weak))
  /usr/include/bits/string_fortified.h:151:8: note: previous definition is here
  __NTH (strlcpy (char *__restrict __dest, const char *__restrict __src,

Fixes: ce99091 ("perf tools: Move strlcpy() from perf to tools/lib/string.c")
Fixes: 0215d59 ("tools lib: Reinstate strlcpy() header guard with __UCLIBC__")
Resolves: https://bugzilla.kernel.org/show_bug.cgi?id=118481
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: stable@vger.kernel.org
---
Changes since v2:
- v2 was failing to compile on gcc-4.9, because there was no `-Wignored-attributes'.
  Make this pragma only efficient for Clang.
Reported-by: kbuild test robot <lkp@intel.com>

Changes since v1:
- Fix compiling with clang due to __weak triggering `-Wignored-attributes'.

 tools/include/linux/string.h | 3 +++
 tools/lib/string.c           | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index 980cb9266718..99ede7f5dfb8 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -17,7 +17,10 @@ int strtobool(const char *s, bool *res);
  * However uClibc headers also define __GLIBC__ hence the hack below
  */
 #if defined(__GLIBC__) && !defined(__UCLIBC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wredundant-decls"
 extern size_t strlcpy(char *dest, const char *src, size_t size);
+#pragma GCC diagnostic pop
 #endif
 
 char *str_error_r(int errnum, char *buf, size_t buflen);
diff --git a/tools/lib/string.c b/tools/lib/string.c
index f2ae1b87c719..f645343815de 100644
--- a/tools/lib/string.c
+++ b/tools/lib/string.c
@@ -96,6 +96,10 @@ int strtobool(const char *s, bool *res)
  * If libc has strlcpy() then that version will override this
  * implementation:
  */
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wignored-attributes"
+#endif
 size_t __weak strlcpy(char *dest, const char *src, size_t size)
 {
 	size_t ret = strlen(src);
@@ -107,6 +111,9 @@ size_t __weak strlcpy(char *dest, const char *src, size_t size)
 	}
 	return ret;
 }
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
 
 /**
  * skip_spaces - Removes leading whitespace from @str.
-- 
2.11.0


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* [tip: perf/core] tools lib: Fix builds when glibc contains strlcpy()
  2019-12-24 17:20 [PATCH v3] tools lib: Fix builds when glibc contains strlcpy Vitaly Chikunov
@ 2020-01-10 17:53 ` tip-bot2 for Vitaly Chikunov
  0 siblings, 0 replies; 2+ messages in thread
From: tip-bot2 for Vitaly Chikunov @ 2020-01-10 17:53 UTC (permalink / raw)
  To: linux-tip-commits
  Cc: Vitaly Chikunov, Dmitry Levin, Josh Poimboeuf, kbuild test robot,
	Peter Zijlstra, stable, Vineet Gupta, Arnaldo Carvalho de Melo,
	x86, LKML

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     6c4798d3f08b81c2c52936b10e0fa872590c96ae
Gitweb:        https://git.kernel.org/tip/6c4798d3f08b81c2c52936b10e0fa872590c96ae
Author:        Vitaly Chikunov <vt@altlinux.org>
AuthorDate:    Tue, 24 Dec 2019 20:20:29 +03:00
Committer:     Arnaldo Carvalho de Melo <acme@redhat.com>
CommitterDate: Mon, 06 Jan 2020 11:46:10 -03:00

tools lib: Fix builds when glibc contains strlcpy()

Disable a couple of compilation warnings (which are treated as errors)
on strlcpy() definition and declaration, allowing users to compile perf
and kernel (objtool) when:

1. glibc have strlcpy() (such as in ALT Linux since 2004) objtool and
   perf build fails with this (in gcc):

  In file included from exec-cmd.c:3:
  tools/include/linux/string.h:20:15: error: redundant redeclaration of ‘strlcpy’ [-Werror=redundant-decls]
     20 | extern size_t strlcpy(char *dest, const char *src, size_t size);

2. clang ignores `-Wredundant-decls', but produces another warning when
   building perf:

    CC       util/string.o
  ../lib/string.c:99:8: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
  size_t __weak strlcpy(char *dest, const char *src, size_t size)
  ../../tools/include/linux/compiler.h:66:34: note: expanded from macro '__weak'
  # define __weak                 __attribute__((weak))
  /usr/include/bits/string_fortified.h:151:8: note: previous definition is here
  __NTH (strlcpy (char *__restrict __dest, const char *__restrict __src,

Committer notes:

The

 #pragma GCC diagnostic

directive was introduced in gcc 4.6, so check for that as well.

Fixes: ce99091 ("perf tools: Move strlcpy() from perf to tools/lib/string.c")
Fixes: 0215d59 ("tools lib: Reinstate strlcpy() header guard with __UCLIBC__")
Resolves: https://bugzilla.kernel.org/show_bug.cgi?id=118481
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
Reviewed-by: Dmitry Levin <ldv@altlinux.org>
Cc: Dmitry Levin <ldv@altlinux.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: kbuild test robot <lkp@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Cc: Vineet Gupta <vineet.gupta1@synopsys.com>
Link: http://lore.kernel.org/lkml/20191224172029.19690-1-vt@altlinux.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/include/linux/string.h | 8 ++++++++
 tools/lib/string.c           | 7 +++++++
 2 files changed, 15 insertions(+)

diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index 980cb92..5e9e781 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -17,7 +17,15 @@ int strtobool(const char *s, bool *res);
  * However uClibc headers also define __GLIBC__ hence the hack below
  */
 #if defined(__GLIBC__) && !defined(__UCLIBC__)
+// pragma diagnostic was introduced in gcc 4.6
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wredundant-decls"
+#endif
 extern size_t strlcpy(char *dest, const char *src, size_t size);
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+#pragma GCC diagnostic pop
+#endif
 #endif
 
 char *str_error_r(int errnum, char *buf, size_t buflen);
diff --git a/tools/lib/string.c b/tools/lib/string.c
index f2ae1b8..f645343 100644
--- a/tools/lib/string.c
+++ b/tools/lib/string.c
@@ -96,6 +96,10 @@ int strtobool(const char *s, bool *res)
  * If libc has strlcpy() then that version will override this
  * implementation:
  */
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wignored-attributes"
+#endif
 size_t __weak strlcpy(char *dest, const char *src, size_t size)
 {
 	size_t ret = strlen(src);
@@ -107,6 +111,9 @@ size_t __weak strlcpy(char *dest, const char *src, size_t size)
 	}
 	return ret;
 }
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
 
 /**
  * skip_spaces - Removes leading whitespace from @str.

^ permalink raw reply related	[flat|nested] 2+ messages in thread

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2019-12-24 17:20 [PATCH v3] tools lib: Fix builds when glibc contains strlcpy Vitaly Chikunov
2020-01-10 17:53 ` [tip: perf/core] tools lib: Fix builds when glibc contains strlcpy() tip-bot2 for Vitaly Chikunov

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