[PATCH] NEWS: Deprecate weak libpthread symbols for single-threaded checks

[PATCH] NEWS: Deprecate weak libpthread symbols for single-threaded checks

[Florian Weimer via Libc-alpha]

Recommend the new __libc_single_thread variable instead.

---
 NEWS | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/NEWS b/NEWS
index 83aed60e19..7fb167e650 100644
--- a/NEWS
+++ b/NEWS
@@ -134,6 +134,14 @@ Deprecated and removed features, and other changes affecting compatibility:
   or contents might be overwritten on subsequent calls in the same thread or
   if the thread is terminated.  It makes strerror MT-safe.
 
+* Using weak references to libpthread functions such as pthread_create
+  or pthread_key_create to detect the singled-threaded nature of a
+  program is an obsolescent feature.  Future versions of glibc will
+  define pthread_create within libc.so.6 itself, so such checks will
+  always flag the program as multi-threaded.  Applications should check
+  the __libc_single_threaded variable declared in
+  <sys/single_threaded.h> instead.
+
 * The "files" NSS module no longer supports the "key" database (used for
   secure RPC).  The contents of the /etc/publickey file will be ignored,
   regardless of the settings in /etc/nsswitch.conf.  (This method of

Re: [PATCH] NEWS: Deprecate weak libpthread symbols for single-threaded checks

[Adhemerval Zanella via Libc-alpha]

On 24/07/2020 11:50, Florian Weimer via Libc-alpha wrote:
> Recommend the new __libc_single_thread variable instead.
> 
> ---
>  NEWS | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/NEWS b/NEWS
> index 83aed60e19..7fb167e650 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -134,6 +134,14 @@ Deprecated and removed features, and other changes affecting compatibility:
>    or contents might be overwritten on subsequent calls in the same thread or
>    if the thread is terminated.  It makes strerror MT-safe.
>  
> +* Using weak references to libpthread functions such as pthread_create
> +  or pthread_key_create to detect the singled-threaded nature of a
> +  program is an obsolescent feature.  Future versions of glibc will
> +  define pthread_create within libc.so.6 itself, so such checks will
> +  always flag the program as multi-threaded.  Applications should check
> +  the __libc_single_threaded variable declared in
> +  <sys/single_threaded.h> instead.
> +
>  * The "files" NSS module no longer supports the "key" database (used for
>    secure RPC).  The contents of the /etc/publickey file will be ignored,
>    regardless of the settings in /etc/nsswitch.conf.  (This method of
> 

Should we add it on the 'Major features' instead along with the single-threaded
entry?

Re: [PATCH] NEWS: Deprecate weak libpthread symbols for single-threaded checks

[Carlos O'Donell via Libc-alpha]

On 7/24/20 12:36 PM, Adhemerval Zanella via Libc-alpha wrote:
> 
> 
> On 24/07/2020 11:50, Florian Weimer via Libc-alpha wrote:
>> Recommend the new __libc_single_thread variable instead.
>>
>> ---
>>  NEWS | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/NEWS b/NEWS
>> index 83aed60e19..7fb167e650 100644
>> --- a/NEWS
>> +++ b/NEWS
>> @@ -134,6 +134,14 @@ Deprecated and removed features, and other changes affecting compatibility:
>>    or contents might be overwritten on subsequent calls in the same thread or
>>    if the thread is terminated.  It makes strerror MT-safe.
>>  
>> +* Using weak references to libpthread functions such as pthread_create
>> +  or pthread_key_create to detect the singled-threaded nature of a
>> +  program is an obsolescent feature.  Future versions of glibc will
>> +  define pthread_create within libc.so.6 itself, so such checks will
>> +  always flag the program as multi-threaded.  Applications should check
>> +  the __libc_single_threaded variable declared in
>> +  <sys/single_threaded.h> instead.
>> +
>>  * The "files" NSS module no longer supports the "key" database (used for
>>    secure RPC).  The contents of the /etc/publickey file will be ignored,
>>    regardless of the settings in /etc/nsswitch.conf.  (This method of
>>
> 
> Should we add it on the 'Major features' instead along with the single-threaded
> entry?

No, it's good to call it out in the deprecated features. People might only
be looking at one or the other so we should have an entry in both.


-- 
Cheers,
Carlos.

Re: [PATCH] NEWS: Deprecate weak libpthread symbols for single-threaded checks

[Carlos O'Donell via Libc-alpha]

On 7/24/20 10:50 AM, Florian Weimer via Libc-alpha wrote:
> Recommend the new __libc_single_thread variable instead.
> 
> ---
>  NEWS | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/NEWS b/NEWS
> index 83aed60e19..7fb167e650 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -134,6 +134,14 @@ Deprecated and removed features, and other changes affecting compatibility:
>    or contents might be overwritten on subsequent calls in the same thread or
>    if the thread is terminated.  It makes strerror MT-safe.
>  
> +* Using weak references to libpthread functions such as pthread_create
> +  or pthread_key_create to detect the singled-threaded nature of a
> +  program is an obsolescent feature.  Future versions of glibc will
> +  define pthread_create within libc.so.6 itself, so such checks will
> +  always flag the program as multi-threaded.  Applications should check
> +  the __libc_single_threaded variable declared in
> +  <sys/single_threaded.h> instead.
> +
>  * The "files" NSS module no longer supports the "key" database (used for
>    secure RPC).  The contents of the /etc/publickey file will be ignored,
>    regardless of the settings in /etc/nsswitch.conf.  (This method of
> 

OK for 2.32.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

-- 
Cheers,
Carlos.