Re: [PATCH v2 1/7] powerpc: properly negate error in syscall_set_return_value()

[Christophe Leroy]

Le 27/01/2025 à 12:20, Dmitry V. Levin a écrit :
> On Thu, Jan 23, 2025 at 11:07:21PM +0100, Christophe Leroy wrote:
> [...]
> > To add a bit more to the confusion,
>
> Looks like there is no end to it:
>
> static inline long regs_return_value(struct pt_regs *regs)
> {
>          if (trap_is_scv(regs))
>                  return regs->gpr[3];
>
>          if (is_syscall_success(regs))
>                  return regs->gpr[3];
>          else
>                  return -regs->gpr[3];
> }
>
> static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
> {
>          regs->gpr[3] = rc;
> }
>
> This doesn't look consistent, does it?

That regs_set_return_value() looks pretty similar to 
syscall_get_return_value().

regs_set_return_value() documentation in asm-generic/syscall.h 
explicitely says: This value is meaningless if syscall_get_error() 
returned nonzero

Is it the same with regs_set_return_value(), only meaningfull where 
there is no error ?

By the way, why have two very similar APIs, one in syscall.h one in 
ptrace.h ?