[PATCH] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[PATCH] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Vinson Lee]

From: Vinson Lee <vlee@twitter.com>

This patch fixes this build error with glibc < 2.6.

  CC       util/cloexec.o
cc1: warnings being treated as errors
util/cloexec.c: In function ‘perf_flag_probe’:
util/cloexec.c:24: error: implicit declaration of function
‘sched_getcpu’
util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
make: *** [util/cloexec.o] Error 1

Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: Vinson Lee <vlee@twitter.com>
---
 tools/perf/util/cloexec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index 47b78b3..3738924 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -7,6 +7,12 @@
 
 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
 
+#ifdef __GLIBC_PREREQ
+#if __GLIBC_PREREQ(2, 6)
+#define HAVE_SCHED_GETCPU
+#endif
+#endif
+
 static int perf_flag_probe(void)
 {
 	/* use 'safest' configuration as used in perf_evsel__fallback() */
@@ -21,9 +27,13 @@ static int perf_flag_probe(void)
 	pid_t pid = -1;
 	char sbuf[STRERR_BUFSIZE];
 
+#ifdef HAVE_SCHED_GETCPU
 	cpu = sched_getcpu();
 	if (cpu < 0)
 		cpu = 0;
+#else
+	cpu = 0;
+#endif
 
 	while (1) {
 		/* check cloexec flag */
-- 
1.8.2.1

Re: [PATCH] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Yann Droneaud]

Hi,

Le vendredi 13 février 2015 à 18:06 -0800, Vinson Lee a écrit :
> From: Vinson Lee <vlee@twitter.com>
> 
> This patch fixes this build error with glibc < 2.6.
> 
>   CC       util/cloexec.o
> cc1: warnings being treated as errors
> util/cloexec.c: In function ‘perf_flag_probe’:
> util/cloexec.c:24: error: implicit declaration of function
> ‘sched_getcpu’
> util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
> make: *** [util/cloexec.o] Error 1
> 
> Cc: stable@vger.kernel.org # 3.18+
> Signed-off-by: Vinson Lee <vlee@twitter.com>
> ---
>  tools/perf/util/cloexec.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
> index 47b78b3..3738924 100644
> --- a/tools/perf/util/cloexec.c
> +++ b/tools/perf/util/cloexec.c
> @@ -7,6 +7,12 @@
>  
>  static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
>  
> +#ifdef __GLIBC_PREREQ
> +#if __GLIBC_PREREQ(2, 6)
> +#define HAVE_SCHED_GETCPU
> +#endif
> +#endif
> +

OK

>  static int perf_flag_probe(void)
>  {
>  	/* use 'safest' configuration as used in perf_evsel__fallback() */
> @@ -21,9 +27,13 @@ static int perf_flag_probe(void)
>  	pid_t pid = -1;
>  	char sbuf[STRERR_BUFSIZE];
>  
> +#ifdef HAVE_SCHED_GETCPU
>  	cpu = sched_getcpu();
>  	if (cpu < 0)
>  		cpu = 0;
> +#else
> +	cpu = 0;
> +#endif
>  
>  	while (1) {
>  		/* check cloexec flag */

I've reviewed the use of __GLIBC_PREREQ(2, 6), but not whether using cpu
= 0 is OK if sched_getcpu() is not available.

Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>

Regards.

-- 
Yann Droneaud
OPTEYA

Re: [PATCH] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Vinson Lee]

On Mon, Feb 16, 2015 at 12:50 PM, Yann Droneaud <ydroneaud@opteya.com> wrote:
> Hi,
>
> Le vendredi 13 février 2015 à 18:06 -0800, Vinson Lee a écrit :
>> From: Vinson Lee <vlee@twitter.com>
>>
>> This patch fixes this build error with glibc < 2.6.
>>
>>   CC       util/cloexec.o
>> cc1: warnings being treated as errors
>> util/cloexec.c: In function ‘perf_flag_probe’:
>> util/cloexec.c:24: error: implicit declaration of function
>> ‘sched_getcpu’
>> util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
>> make: *** [util/cloexec.o] Error 1
>>
>> Cc: stable@vger.kernel.org # 3.18+
>> Signed-off-by: Vinson Lee <vlee@twitter.com>
>> ---
>>  tools/perf/util/cloexec.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
>> index 47b78b3..3738924 100644
>> --- a/tools/perf/util/cloexec.c
>> +++ b/tools/perf/util/cloexec.c
>> @@ -7,6 +7,12 @@
>>
>>  static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
>>
>> +#ifdef __GLIBC_PREREQ
>> +#if __GLIBC_PREREQ(2, 6)
>> +#define HAVE_SCHED_GETCPU
>> +#endif
>> +#endif
>> +
>
> OK
>
>>  static int perf_flag_probe(void)
>>  {
>>       /* use 'safest' configuration as used in perf_evsel__fallback() */
>> @@ -21,9 +27,13 @@ static int perf_flag_probe(void)
>>       pid_t pid = -1;
>>       char sbuf[STRERR_BUFSIZE];
>>
>> +#ifdef HAVE_SCHED_GETCPU
>>       cpu = sched_getcpu();
>>       if (cpu < 0)
>>               cpu = 0;
>> +#else
>> +     cpu = 0;
>> +#endif
>>
>>       while (1) {
>>               /* check cloexec flag */
>
> I've reviewed the use of __GLIBC_PREREQ(2, 6), but not whether using cpu
> = 0 is OK if sched_getcpu() is not available.
>
> Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
>
> Regards.
>
> --
> Yann Droneaud
> OPTEYA
>
>
>

Ping. Please review the sched_getcpu hunk.

Re: [PATCH] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Peter Zijlstra]

On Tue, Mar 17, 2015 at 04:49:13PM -0700, Vinson Lee wrote:
> On Mon, Feb 16, 2015 at 12:50 PM, Yann Droneaud <ydroneaud@opteya.com> wrote:
> >> +#ifdef __GLIBC_PREREQ
> >> +#if __GLIBC_PREREQ(2, 6)
> >> +#define HAVE_SCHED_GETCPU
> >> +#endif
> >> +#endif

> >> @@ -21,9 +27,13 @@ static int perf_flag_probe(void)
> >>       pid_t pid = -1;
> >>       char sbuf[STRERR_BUFSIZE];
> >>
> >> +#ifdef HAVE_SCHED_GETCPU
> >>       cpu = sched_getcpu();
> >>       if (cpu < 0)
> >>               cpu = 0;
> >> +#else
> >> +     cpu = 0;
> >> +#endif
> >>
> >>       while (1) {
> >>               /* check cloexec flag */

Would it not be much nicer to implement a sched_getcpu() stub that
returns -1 and sets errno to -ENOSYS or something?

That avoids the magic #ifdef mushroom.

[PATCH v2] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Vinson Lee]

From: Vinson Lee <vlee@twitter.com>

This patch fixes this build error with glibc < 2.6.

  CC       util/cloexec.o
cc1: warnings being treated as errors
util/cloexec.c: In function ‘perf_flag_probe’:
util/cloexec.c:24: error: implicit declaration of function
‘sched_getcpu’
util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
make: *** [util/cloexec.o] Error 1

Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: Vinson Lee <vlee@twitter.com>
---
 tools/perf/util/cloexec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index 6da965b..285bd70 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -7,6 +7,16 @@
 
 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
 
+#ifdef __GLIBC_PREREQ
+#if !__GLIBC_PREREQ(2, 6)
+static int sched_getcpu(void)
+{
+	errno = ENOSYS;
+	return -1;
+}
+#endif
+#endif
+
 static int perf_flag_probe(void)
 {
 	/* use 'safest' configuration as used in perf_evsel__fallback() */
-- 
1.8.2.1

Re: [PATCH v2] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Jiri Olsa]

On Wed, Mar 18, 2015 at 04:11:52PM -0700, Vinson Lee wrote:
> From: Vinson Lee <vlee@twitter.com>
> 
> This patch fixes this build error with glibc < 2.6.
> 
>   CC       util/cloexec.o
> cc1: warnings being treated as errors
> util/cloexec.c: In function ‘perf_flag_probe’:
> util/cloexec.c:24: error: implicit declaration of function
> ‘sched_getcpu’
> util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
> make: *** [util/cloexec.o] Error 1
> 
> Cc: stable@vger.kernel.org # 3.18+
> Signed-off-by: Vinson Lee <vlee@twitter.com>
> ---
>  tools/perf/util/cloexec.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
> index 6da965b..285bd70 100644
> --- a/tools/perf/util/cloexec.c
> +++ b/tools/perf/util/cloexec.c
> @@ -7,6 +7,16 @@
>  
>  static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
>  
> +#ifdef __GLIBC_PREREQ
> +#if !__GLIBC_PREREQ(2, 6)
> +static int sched_getcpu(void)
> +{
> +	errno = ENOSYS;
> +	return -1;
> +}
> +#endif
> +#endif

you could mark it as __weak and get rid of those ifdef's
like we do for strlcpy in utilpath.c

jirka

Re: [PATCH v2] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Arnaldo Carvalho de Melo]

Em Thu, Mar 19, 2015 at 11:13:04AM +0100, Jiri Olsa escreveu:
> On Wed, Mar 18, 2015 at 04:11:52PM -0700, Vinson Lee wrote:
> > This patch fixes this build error with glibc < 2.6.

> > +#ifdef __GLIBC_PREREQ
> > +#if !__GLIBC_PREREQ(2, 6)
> > +static int sched_getcpu(void)
> > +{
> > +	errno = ENOSYS;
> > +	return -1;
> > +}
> > +#endif
> > +#endif
 
> you could mark it as __weak and get rid of those ifdef's
> like we do for strlcpy in utilpath.c

Agreed.

- Arnaldo

Re: [PATCH v2] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Vinson Lee]

On Thu, Mar 19, 2015 at 6:14 AM, Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
> Em Thu, Mar 19, 2015 at 11:13:04AM +0100, Jiri Olsa escreveu:
>> On Wed, Mar 18, 2015 at 04:11:52PM -0700, Vinson Lee wrote:
>> > This patch fixes this build error with glibc < 2.6.
>
>> > +#ifdef __GLIBC_PREREQ
>> > +#if !__GLIBC_PREREQ(2, 6)
>> > +static int sched_getcpu(void)
>> > +{
>> > +   errno = ENOSYS;
>> > +   return -1;
>> > +}
>> > +#endif
>> > +#endif
>
>> you could mark it as __weak and get rid of those ifdef's
>> like we do for strlcpy in utilpath.c
>
> Agreed.
>
> - Arnaldo

I tried this approach but am having trouble getting a patch to compile
with both older glibc and recent glibc.

With older glibc I will get a "no previous prototype" compilation
error. I can fix this error by adding a prototype but this results in
a "redundant redeclaration" error with newer glibc.

Re: [PATCH v2] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Arnaldo Carvalho de Melo]

Em Thu, Mar 19, 2015 at 02:12:05PM -0700, Vinson Lee escreveu:
> On Thu, Mar 19, 2015 at 6:14 AM, Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
> > Em Thu, Mar 19, 2015 at 11:13:04AM +0100, Jiri Olsa escreveu:
> >> On Wed, Mar 18, 2015 at 04:11:52PM -0700, Vinson Lee wrote:
> >> > This patch fixes this build error with glibc < 2.6.
> >
> >> > +#ifdef __GLIBC_PREREQ
> >> > +#if !__GLIBC_PREREQ(2, 6)
> >> > +static int sched_getcpu(void)
> >> > +{
> >> > +   errno = ENOSYS;
> >> > +   return -1;
> >> > +}
> >> > +#endif
> >> > +#endif
> >
> >> you could mark it as __weak and get rid of those ifdef's
> >> like we do for strlcpy in utilpath.c
> >
> > Agreed.
 
> I tried this approach but am having trouble getting a patch to compile
> with both older glibc and recent glibc.
 
> With older glibc I will get a "no previous prototype" compilation
> error. I can fix this error by adding a prototype but this results in
> a "redundant redeclaration" error with newer glibc.

So for strlcpy we have in tools/perf/util/cache.h:

#ifndef __UCLIBC__
/* Matches the libc/libbsd function attribute so we declare this
 * unconditionally: */
extern size_t strlcpy(char *dest, const char *src, size_t size);
#endif

I.e. have the ifdef just in the header file.

This way, if we end up needing to use sched_getcpu elsewhere, it will
work and the needed #ifdef will be constrained to the header file.

At some point we should try to move these functions to some
libc-compat.c file and move it to somewhere in tools/lib/.

- Arnaldo

Re: [PATCH v2] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Vinson Lee]

On Fri, Mar 20, 2015 at 6:03 AM, Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
> Em Thu, Mar 19, 2015 at 02:12:05PM -0700, Vinson Lee escreveu:
>> On Thu, Mar 19, 2015 at 6:14 AM, Arnaldo Carvalho de Melo
>> <acme@kernel.org> wrote:
>> > Em Thu, Mar 19, 2015 at 11:13:04AM +0100, Jiri Olsa escreveu:
>> >> On Wed, Mar 18, 2015 at 04:11:52PM -0700, Vinson Lee wrote:
>> >> > This patch fixes this build error with glibc < 2.6.
>> >
>> >> > +#ifdef __GLIBC_PREREQ
>> >> > +#if !__GLIBC_PREREQ(2, 6)
>> >> > +static int sched_getcpu(void)
>> >> > +{
>> >> > +   errno = ENOSYS;
>> >> > +   return -1;
>> >> > +}
>> >> > +#endif
>> >> > +#endif
>> >
>> >> you could mark it as __weak and get rid of those ifdef's
>> >> like we do for strlcpy in utilpath.c
>> >
>> > Agreed.
>
>> I tried this approach but am having trouble getting a patch to compile
>> with both older glibc and recent glibc.
>
>> With older glibc I will get a "no previous prototype" compilation
>> error. I can fix this error by adding a prototype but this results in
>> a "redundant redeclaration" error with newer glibc.
>
> So for strlcpy we have in tools/perf/util/cache.h:
>
> #ifndef __UCLIBC__
> /* Matches the libc/libbsd function attribute so we declare this
>  * unconditionally: */
> extern size_t strlcpy(char *dest, const char *src, size_t size);
> #endif
>
> I.e. have the ifdef just in the header file.
>
> This way, if we end up needing to use sched_getcpu elsewhere, it will
> work and the needed #ifdef will be constrained to the header file.
>
> At some point we should try to move these functions to some
> libc-compat.c file and move it to somewhere in tools/lib/.
>
> - Arnaldo


I tried moving the prototype to a header file and it does not compile
with newer glibc for me either. I still get a "redundant
redeclaration" compiler error.

Here is the diff that I tried.

diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index 6da965b..85b5238 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -7,6 +7,12 @@

 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;

+int __weak sched_getcpu(void)
+{
+       errno = ENOSYS;
+       return -1;
+}
+
 static int perf_flag_probe(void)
 {
        /* use 'safest' configuration as used in perf_evsel__fallback() */
diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h
index 94a5a7d..06904bc 100644
--- a/tools/perf/util/cloexec.h
+++ b/tools/perf/util/cloexec.h
@@ -3,4 +3,6 @@

 unsigned long perf_event_open_cloexec_flag(void);

+extern int sched_getcpu(void) __THROW;
+
 #endif /* __PERF_CLOEXEC_H */

Re: [PATCH v2] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Arnaldo Carvalho de Melo]

Em Fri, Mar 20, 2015 at 11:44:42AM -0700, Vinson Lee escreveu:
> On Fri, Mar 20, 2015 at 6:03 AM, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > So for strlcpy we have in tools/perf/util/cache.h:

> > #ifndef __UCLIBC__
> > /* Matches the libc/libbsd function attribute so we declare this
> >  * unconditionally: */
> > extern size_t strlcpy(char *dest, const char *src, size_t size);
> > #endif

> > I.e. have the ifdef just in the header file.

This part you didn't take into account, the __weak marked part is ok,
the linker will DTRT with that, its just the redeclaration part that
needs to get out of the way, enclose that under appropriate ifdef, i.e.
one that is associated with the libc where that file first appeared and
that has been present since then.

- Arnaldo

> > This way, if we end up needing to use sched_getcpu elsewhere, it will
> > work and the needed #ifdef will be constrained to the header file.
 
> I tried moving the prototype to a header file and it does not compile
> with newer glibc for me either. I still get a "redundant
> redeclaration" compiler error.
 
> Here is the diff that I tried.
 
> diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
> @@ -7,6 +7,12 @@
> 
>  static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
> 
> +int __weak sched_getcpu(void)
> +{
> +       errno = ENOSYS;
> +       return -1;
> +}
> +
>  static int perf_flag_probe(void)
>  {
>         /* use 'safest' configuration as used in perf_evsel__fallback() */
> diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h
> @@ -3,4 +3,6 @@
> 
>  unsigned long perf_event_open_cloexec_flag(void);
> 
> +extern int sched_getcpu(void) __THROW;
> +
>  #endif /* __PERF_CLOEXEC_H */

[PATCH v3] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Vinson Lee]

From: Vinson Lee <vlee@twitter.com>

This patch fixes this build error with glibc < 2.6.

  CC       util/cloexec.o
cc1: warnings being treated as errors
util/cloexec.c: In function ‘perf_flag_probe’:
util/cloexec.c:24: error: implicit declaration of function
‘sched_getcpu’
util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
make: *** [util/cloexec.o] Error 1

Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: Vinson Lee <vlee@twitter.com>
---
 tools/perf/util/cloexec.c | 6 ++++++
 tools/perf/util/cloexec.h | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index 6da965b..85b5238 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -7,6 +7,12 @@
 
 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
 
+int __weak sched_getcpu(void)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
 static int perf_flag_probe(void)
 {
 	/* use 'safest' configuration as used in perf_evsel__fallback() */
diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h
index 94a5a7d..68888c2 100644
--- a/tools/perf/util/cloexec.h
+++ b/tools/perf/util/cloexec.h
@@ -3,4 +3,10 @@
 
 unsigned long perf_event_open_cloexec_flag(void);
 
+#ifdef __GLIBC_PREREQ
+#if !__GLIBC_PREREQ(2, 6)
+extern int sched_getcpu(void) __THROW;
+#endif
+#endif
+
 #endif /* __PERF_CLOEXEC_H */
-- 
1.8.2.1

Re: [PATCH v3] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Namhyung Kim]

Hi Vinson,

On Mon, Mar 23, 2015 at 12:09:16PM -0700, Vinson Lee wrote:
> From: Vinson Lee <vlee@twitter.com>
> 
> This patch fixes this build error with glibc < 2.6.
> 
>   CC       util/cloexec.o
> cc1: warnings being treated as errors
> util/cloexec.c: In function ‘perf_flag_probe’:
> util/cloexec.c:24: error: implicit declaration of function
> ‘sched_getcpu’
> util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
> make: *** [util/cloexec.o] Error 1
> 
> Cc: stable@vger.kernel.org # 3.18+
> Signed-off-by: Vinson Lee <vlee@twitter.com>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung


> ---
>  tools/perf/util/cloexec.c | 6 ++++++
>  tools/perf/util/cloexec.h | 6 ++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
> index 6da965b..85b5238 100644
> --- a/tools/perf/util/cloexec.c
> +++ b/tools/perf/util/cloexec.c
> @@ -7,6 +7,12 @@
>  
>  static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
>  
> +int __weak sched_getcpu(void)
> +{
> +	errno = ENOSYS;
> +	return -1;
> +}
> +
>  static int perf_flag_probe(void)
>  {
>  	/* use 'safest' configuration as used in perf_evsel__fallback() */
> diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h
> index 94a5a7d..68888c2 100644
> --- a/tools/perf/util/cloexec.h
> +++ b/tools/perf/util/cloexec.h
> @@ -3,4 +3,10 @@
>  
>  unsigned long perf_event_open_cloexec_flag(void);
>  
> +#ifdef __GLIBC_PREREQ
> +#if !__GLIBC_PREREQ(2, 6)
> +extern int sched_getcpu(void) __THROW;
> +#endif
> +#endif
> +
>  #endif /* __PERF_CLOEXEC_H */
> -- 
> 1.8.2.1
> 
> --
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Re: [PATCH v3] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[Jiri Olsa]

On Mon, Mar 23, 2015 at 12:09:16PM -0700, Vinson Lee wrote:
> From: Vinson Lee <vlee@twitter.com>
> 
> This patch fixes this build error with glibc < 2.6.
> 
>   CC       util/cloexec.o
> cc1: warnings being treated as errors
> util/cloexec.c: In function ‘perf_flag_probe’:
> util/cloexec.c:24: error: implicit declaration of function
> ‘sched_getcpu’
> util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
> make: *** [util/cloexec.o] Error 1
> 
> Cc: stable@vger.kernel.org # 3.18+
> Signed-off-by: Vinson Lee <vlee@twitter.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> ---
>  tools/perf/util/cloexec.c | 6 ++++++
>  tools/perf/util/cloexec.h | 6 ++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
> index 6da965b..85b5238 100644
> --- a/tools/perf/util/cloexec.c
> +++ b/tools/perf/util/cloexec.c
> @@ -7,6 +7,12 @@
>  
>  static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
>  
> +int __weak sched_getcpu(void)
> +{
> +	errno = ENOSYS;
> +	return -1;
> +}
> +
>  static int perf_flag_probe(void)
>  {
>  	/* use 'safest' configuration as used in perf_evsel__fallback() */
> diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h
> index 94a5a7d..68888c2 100644
> --- a/tools/perf/util/cloexec.h
> +++ b/tools/perf/util/cloexec.h
> @@ -3,4 +3,10 @@
>  
>  unsigned long perf_event_open_cloexec_flag(void);
>  
> +#ifdef __GLIBC_PREREQ
> +#if !__GLIBC_PREREQ(2, 6)
> +extern int sched_getcpu(void) __THROW;
> +#endif
> +#endif
> +
>  #endif /* __PERF_CLOEXEC_H */
> -- 
> 1.8.2.1
> 

[tip:perf/core] perf tools: Work around lack of sched_getcpu in glibc < 2.6.

[tip-bot for Vinson Lee]

Commit-ID:  e1e455f4f4d35850c30235747620d0d078fe9f64
Gitweb:     http://git.kernel.org/tip/e1e455f4f4d35850c30235747620d0d078fe9f64
Author:     Vinson Lee <vlee@twitter.com>
AuthorDate: Mon, 23 Mar 2015 12:09:16 -0700
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 24 Mar 2015 12:08:07 -0300

perf tools: Work around lack of sched_getcpu in glibc < 2.6.

This patch fixes this build error with glibc < 2.6.

  CC       util/cloexec.o
cc1: warnings being treated as errors
util/cloexec.c: In function ‘perf_flag_probe’:
util/cloexec.c:24: error: implicit declaration of function
‘sched_getcpu’
util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
make: *** [util/cloexec.o] Error 1

Signed-off-by: Vinson Lee <vlee@twitter.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: stable@vger.kernel.org # 3.18+
Link: http://lkml.kernel.org/r/1427137761-16119-1-git-send-email-vlee@twopensource.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/cloexec.c | 6 ++++++
 tools/perf/util/cloexec.h | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index 6da965b..85b5238 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -7,6 +7,12 @@
 
 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
 
+int __weak sched_getcpu(void)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
 static int perf_flag_probe(void)
 {
 	/* use 'safest' configuration as used in perf_evsel__fallback() */
diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h
index 94a5a7d..68888c2 100644
--- a/tools/perf/util/cloexec.h
+++ b/tools/perf/util/cloexec.h
@@ -3,4 +3,10 @@
 
 unsigned long perf_event_open_cloexec_flag(void);
 
+#ifdef __GLIBC_PREREQ
+#if !__GLIBC_PREREQ(2, 6)
+extern int sched_getcpu(void) __THROW;
+#endif
+#endif
+
 #endif /* __PERF_CLOEXEC_H */