[PATCH] Fix __fp_lock_all() and __fp_unlock_all()

[PATCH] Fix __fp_lock_all() and __fp_unlock_all()

[Sebastian Huber]

For _REENT_GLOBAL_STDIO_STREAMS, lock/unlock all FILE objects.  In the
repository, this function is only used by Cygwin during process forks.  Since
Cygwin enabled _REENT_GLOBAL_STDIO_STREAMS recently, without this fix no FILE
object at all was locked.
---
 newlib/libc/stdio/findfp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
index 6933ff1db..a39082387 100644
--- a/newlib/libc/stdio/findfp.c
+++ b/newlib/libc/stdio/findfp.c
@@ -333,6 +333,8 @@ __fp_lock_all (void)
 #ifndef _REENT_GLOBAL_STDIO_STREAMS
   ptr = _REENT;
   (void) _fwalk_sglue (ptr, __fp_lock, &ptr->__sglue);
+#else
+  (void) _fwalk_sglue (NULL, __fp_lock, &__sglue);
 #endif
 }
 
@@ -344,6 +346,8 @@ __fp_unlock_all (void)
 
   ptr = _REENT;
   (void) _fwalk_sglue (ptr, __fp_unlock, &ptr->__sglue);
+#else
+  (void) _fwalk_sglue (NULL, __fp_unlock, &__sglue);
 #endif
 
   __sfp_lock_release ();
-- 
2.35.3

[PATCH] Fix __sFILE::_lock initialization

[Sebastian Huber]

The __sFILE::_lock member is present if __SINGLE_THREAD__ is not defined.  In
this case, it is initialized in __sfp().  It is a bug to do it sometimes also
in std().
---
 newlib/libc/stdio/findfp.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
index 118637a18..6933ff1db 100644
--- a/newlib/libc/stdio/findfp.c
+++ b/newlib/libc/stdio/findfp.c
@@ -97,14 +97,6 @@ std (FILE *ptr,
 #else /* _STDIO_CLOSE_STD_STREAMS */
   ptr->_close = NULL;
 #endif /* _STDIO_CLOSE_STD_STREAMS */
-#if !defined(__SINGLE_THREAD__) && !(defined(_REENT_SMALL) && !defined(_REENT_GLOBAL_STDIO_STREAMS))
-  __lock_init_recursive (ptr->_lock);
-  /*
-   * #else
-   * lock is already initialized in __sfp
-   */
-#endif
-
 #ifdef __SCLE
   if (__stextmode (ptr->_file))
     ptr->_flags |= __SCLE;
-- 
2.35.3

[PATCH] Use weak reference for _REENT_SMALL

[Sebastian Huber]

Avoid a strong reference to __sfp[] for _impure_data.  The __sfp[] is linked in
if __sinit() is used for example.
---
 newlib/libc/reent/impure.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/newlib/libc/reent/impure.c b/newlib/libc/reent/impure.c
index f10665fd0..643a511c6 100644
--- a/newlib/libc/reent/impure.c
+++ b/newlib/libc/reent/impure.c
@@ -6,10 +6,14 @@
    important to reduce image size for targets with very small amounts
    of memory.  */
 #ifdef _REENT_SMALL
+#ifdef _REENT_GLOBAL_STDIO_STREAMS
+extern __FILE __sf[3] _ATTRIBUTE ((weak));
+#else
 extern const struct __sFILE_fake __sf_fake_stdin _ATTRIBUTE ((weak));
 extern const struct __sFILE_fake __sf_fake_stdout _ATTRIBUTE ((weak));
 extern const struct __sFILE_fake __sf_fake_stderr _ATTRIBUTE ((weak));
 #endif
+#endif
 
 struct _reent __ATTRIBUTE_IMPURE_DATA__ _impure_data = _REENT_INIT (_impure_data);
 #ifdef __CYGWIN__
-- 
2.35.3

Re: [PATCH] Fix __fp_lock_all() and __fp_unlock_all()

[Corinna Vinschen]

On May 18 19:13, Sebastian Huber wrote:
> For _REENT_GLOBAL_STDIO_STREAMS, lock/unlock all FILE objects.  In the
> repository, this function is only used by Cygwin during process forks.  Since
> Cygwin enabled _REENT_GLOBAL_STDIO_STREAMS recently, without this fix no FILE
> object at all was locked.
> ---
>  newlib/libc/stdio/findfp.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
> index 6933ff1db..a39082387 100644
> --- a/newlib/libc/stdio/findfp.c
> +++ b/newlib/libc/stdio/findfp.c
> @@ -333,6 +333,8 @@ __fp_lock_all (void)
>  #ifndef _REENT_GLOBAL_STDIO_STREAMS
>    ptr = _REENT;
>    (void) _fwalk_sglue (ptr, __fp_lock, &ptr->__sglue);
> +#else
> +  (void) _fwalk_sglue (NULL, __fp_lock, &__sglue);
>  #endif

The resulting __fp_lock_all/__fp_unlock_all functions look a bit weird
to me, codewise. Counter-proposal:

diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
index 118637a18f5b..ebfbf0976de5 100644
--- a/newlib/libc/stdio/findfp.c
+++ b/newlib/libc/stdio/findfp.c
@@ -329,31 +329,24 @@ __fp_unlock (struct _reent * ptr __unused, FILE * fp)
   return 0;
 }
 
+#ifdef _REENT_GLOBAL_STDIO_STREAMS
+# define _PTR NULL
+# define _GLUE __sglue
+#else
+# define _PTR _REENT
+# define _GLUE _PTR->__sglue
+#endif
+
 void
 __fp_lock_all (void)
 {
-#ifndef _REENT_GLOBAL_STDIO_STREAMS
-  struct _reent *ptr;
-#endif
-
-  __sfp_lock_acquire ();
-
-#ifndef _REENT_GLOBAL_STDIO_STREAMS
-  ptr = _REENT;
-  (void) _fwalk_sglue (ptr, __fp_lock, &ptr->__sglue);
-#endif
+  _fwalk_sglue (_PTR, __fp_lock, &_GLUE);
 }
 
 void
 __fp_unlock_all (void)
 {
-#ifndef _REENT_GLOBAL_STDIO_STREAMS
-  struct _reent *ptr;
-
-  ptr = _REENT;
-  (void) _fwalk_sglue (ptr, __fp_unlock, &ptr->__sglue);
-#endif
-
+  _fwalk_sglue (_PTR, __fp_unlock, &_GLUE);
   __sfp_lock_release ();
 }
 #endif

What do you think?


Thanks,
Corinna

Re: [PATCH] Fix __sFILE::_lock initialization

[Corinna Vinschen]

On May 18 19:13, Sebastian Huber wrote:
> The __sFILE::_lock member is present if __SINGLE_THREAD__ is not defined.  In
> this case, it is initialized in __sfp().  It is a bug to do it sometimes also
> in std().
> ---
>  newlib/libc/stdio/findfp.c | 8 --------
>  1 file changed, 8 deletions(-)
> 
> diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
> index 118637a18..6933ff1db 100644
> --- a/newlib/libc/stdio/findfp.c
> +++ b/newlib/libc/stdio/findfp.c
> @@ -97,14 +97,6 @@ std (FILE *ptr,
>  #else /* _STDIO_CLOSE_STD_STREAMS */
>    ptr->_close = NULL;
>  #endif /* _STDIO_CLOSE_STD_STREAMS */
> -#if !defined(__SINGLE_THREAD__) && !(defined(_REENT_SMALL) && !defined(_REENT_GLOBAL_STDIO_STREAMS))
> -  __lock_init_recursive (ptr->_lock);
> -  /*
> -   * #else
> -   * lock is already initialized in __sfp
> -   */
> -#endif
> -
>  #ifdef __SCLE
>    if (__stextmode (ptr->_file))
>      ptr->_flags |= __SCLE;
> -- 
> 2.35.3

LGTM


Thx,
Corinna

Re: [PATCH] Use weak reference for _REENT_SMALL

[Corinna Vinschen]

On May 18 19:13, Sebastian Huber wrote:
> Avoid a strong reference to __sfp[] for _impure_data.  The __sfp[] is linked in
> if __sinit() is used for example.
> ---
>  newlib/libc/reent/impure.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/newlib/libc/reent/impure.c b/newlib/libc/reent/impure.c
> index f10665fd0..643a511c6 100644
> --- a/newlib/libc/reent/impure.c
> +++ b/newlib/libc/reent/impure.c
> @@ -6,10 +6,14 @@
>     important to reduce image size for targets with very small amounts
>     of memory.  */
>  #ifdef _REENT_SMALL
> +#ifdef _REENT_GLOBAL_STDIO_STREAMS
> +extern __FILE __sf[3] _ATTRIBUTE ((weak));
> +#else
>  extern const struct __sFILE_fake __sf_fake_stdin _ATTRIBUTE ((weak));
>  extern const struct __sFILE_fake __sf_fake_stdout _ATTRIBUTE ((weak));
>  extern const struct __sFILE_fake __sf_fake_stderr _ATTRIBUTE ((weak));
>  #endif
> +#endif
>  
>  struct _reent __ATTRIBUTE_IMPURE_DATA__ _impure_data = _REENT_INIT (_impure_data);
>  #ifdef __CYGWIN__
> -- 
> 2.35.3

Ok.


Thx,
Corinna

Re: [PATCH] Fix __fp_lock_all() and __fp_unlock_all()

[Sebastian Huber]

On 19/05/2022 14:02, Corinna Vinschen wrote:
> On May 18 19:13, Sebastian Huber wrote:
>> For _REENT_GLOBAL_STDIO_STREAMS, lock/unlock all FILE objects.  In the
>> repository, this function is only used by Cygwin during process forks.  Since
>> Cygwin enabled _REENT_GLOBAL_STDIO_STREAMS recently, without this fix no FILE
>> object at all was locked.
>> ---
>>   newlib/libc/stdio/findfp.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
>> index 6933ff1db..a39082387 100644
>> --- a/newlib/libc/stdio/findfp.c
>> +++ b/newlib/libc/stdio/findfp.c
>> @@ -333,6 +333,8 @@ __fp_lock_all (void)
>>   #ifndef _REENT_GLOBAL_STDIO_STREAMS
>>     ptr = _REENT;
>>     (void) _fwalk_sglue (ptr, __fp_lock, &ptr->__sglue);
>> +#else
>> +  (void) _fwalk_sglue (NULL, __fp_lock, &__sglue);
>>   #endif
> 
> The resulting __fp_lock_all/__fp_unlock_all functions look a bit weird
> to me, codewise. Counter-proposal:
> 
> diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
> index 118637a18f5b..ebfbf0976de5 100644
> --- a/newlib/libc/stdio/findfp.c
> +++ b/newlib/libc/stdio/findfp.c
> @@ -329,31 +329,24 @@ __fp_unlock (struct _reent * ptr __unused, FILE * fp)
>     return 0;
>   }
>   
> +#ifdef _REENT_GLOBAL_STDIO_STREAMS
> +# define _PTR NULL
> +# define _GLUE __sglue
> +#else
> +# define _PTR _REENT
> +# define _GLUE _PTR->__sglue
> +#endif
> +
>   void
>   __fp_lock_all (void)
>   {
> -#ifndef _REENT_GLOBAL_STDIO_STREAMS
> -  struct _reent *ptr;
> -#endif
> -
> -  __sfp_lock_acquire ();
> -
> -#ifndef _REENT_GLOBAL_STDIO_STREAMS
> -  ptr = _REENT;
> -  (void) _fwalk_sglue (ptr, __fp_lock, &ptr->__sglue);
> -#endif
> +  _fwalk_sglue (_PTR, __fp_lock, &_GLUE);
>   }
>   
>   void
>   __fp_unlock_all (void)
>   {
> -#ifndef _REENT_GLOBAL_STDIO_STREAMS
> -  struct _reent *ptr;
> -
> -  ptr = _REENT;
> -  (void) _fwalk_sglue (ptr, __fp_unlock, &ptr->__sglue);
> -#endif
> -
> +  _fwalk_sglue (_PTR, __fp_unlock, &_GLUE);
>     __sfp_lock_release ();
>   }
>   #endif
> 
> What do you think?

This patch was a preparation for this proposal:

https://sourceware.org/pipermail/newlib/2022/019735.html

It is a behaviour change for the default Newlib configuration, however, 
from my point of view it is more or less a bug fix.

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