AW: [PATCH, newlib] Allow locking routine to be retargeted

[onkel.jack@t-online.de]

Hello,

to unconditionally provide weak dummy implementation I dont think its a good idea since it has some implications:
If the newlib is compiled for single thread, no locks are required at all, so the dummy implementation/macro is doing the job to
satisfy the linker.
But for multithread its dangerous to provide a dummy since you would not see first hand there are no locks but dummys.

So my suggestion would be:
- For single thread leave the implementation as is.
- For multithread, dont provide any lock function, so linking newlib without to provide locking functions from os/kernel 
would result in a linkage error, therefore forces the user not to forget to provide them.

So I think, just put something like #ifndef MULTI_THREAD around the existing macros would do it. 






-----Original-Nachricht-----
Betreff: Re: [PATCH, newlib] Allow locking routine to be retargeted
Datum: 2016-11-10T21:35:30+0100
Von: "Freddie Chopin" <freddie_chopin@op.pl>
An: "newlib@sourceware.org" <newlib@sourceware.org>

On Thu, 2016-11-10 at 21:32 +0100, Freddie Chopin wrote:
> void __lock_acquire(_LOCK_T lock)
> {
> 	if (lock == 0)
> 	{
> 		// lock not yet really initialized...
> 		disableInterrupts();
> 		if (lock == 0)	// re-check due to possible race
> condition
> 			lock = malloc(sizeof(RealMutexFromYourRtos));
> 
> 		assert(lock != 0);
> 		rtos_mutex_create(lock);
> 		enableInterrupts();
> 	}
> 
> 	rtos_mutex_lock((RealMutexFromYourRtos*)lock);
> }

I've obviously missed some curly braces for the inner "if", but I guess
you get my idea anyway (;

Regards,
FCh