Re: [PATCH/gdbserver] Remove current_inferior's save/restore when call get_thread_regcache.

[Yao Qi <yao@codesourcery.com>]

On 05/04/2012 08:31 PM, Pedro Alves wrote:
>> > -  regcache = get_thread_regcache (current_inferior, 1);
>> > +  regcache = get_thread_regcache (get_lwp_thread (lwp), 1);
>> >    pc = (*the_low_target.get_pc) (regcache);
> 
> No, the_low_target.get_pc also needs to go to the right inferior.
> 

I thought the_low_target.get_pc is to extract value of pc from regcache,
so inferior is not needed.  I examined linux-foo-low.c files again, and
find only ppc_get_pc needs the right inferior, sigh.

>> >  
>> >    return child;
>> > diff --git a/gdb/gdbserver/proc-service.c b/gdb/gdbserver/proc-service.c
>> > index 5584dab..d4c17a2 100644
>> > --- a/gdb/gdbserver/proc-service.c
>> > +++ b/gdb/gdbserver/proc-service.c
>> > @@ -99,20 +99,15 @@ ps_lgetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, prgregset_t gregset)
>> >  {
>> >  #ifdef HAVE_REGSETS
>> >    struct lwp_info *lwp;
>> > -  struct thread_info *reg_inferior, *save_inferior;
>> >    struct regcache *regcache;
>> >  
>> >    lwp = find_lwp_pid (pid_to_ptid (lwpid));
>> >    if (lwp == NULL)
>> >      return PS_ERR;
>> >  
>> > -  reg_inferior = get_lwp_thread (lwp);
>> > -  save_inferior = current_inferior;
>> > -  current_inferior = reg_inferior;
>> > -  regcache = get_thread_regcache (current_inferior, 1);
>> > +  regcache = get_thread_regcache (get_lwp_thread (lwp), 1);
>> >    gregset_info ()->fill_function (regcache, gregset);
> 
> Ditto the whole gregset_info ()->fill_function line, particularly
> after my multi-process/multi-arch series, while the fill_function
> depends on inferior.
> 

So any code needs inferior should be wrapped in the follow manner?

save_inferior = current_inferior;
current_inferior = reg_inferior;
....
....
current_inferior = save_inferior;

The following question is what functions need inferior?  AFAICS, all the
methods in the_low_target and functions in `struct regset_info' need
inferior.  Anything else?

If methods in the_low_target may need inferior, all the usage of
the_low_target methods should be wrapped by the block above.  Is it
correct?  I hope I am wrong :)

-- 
Yao (齐尧)