[petsc-dev] GASM

[Barry Smith]

  I think Jed is suggesting changing:

PetscErrorCode  KSPDestroy(KSP *ksp)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  if (!*ksp) PetscFunctionReturn(0);
  PetscValidHeaderSpecific((*ksp),KSP_CLASSID,1);
  if (--((PetscObject)(*ksp))->refct > 0) {*ksp = 0; PetscFunctionReturn(0);}

  ierr = KSPReset((*ksp));CHKERRQ(ierr);



to 


PetscErrorCode  KSPDestroy(KSP *ksp)
{
  PetscErrorCode ierr;
  PC                         pc = (*ksp)->pc;

  PetscFunctionBegin;
  if (!*ksp) PetscFunctionReturn(0);
  PetscValidHeaderSpecific((*ksp),KSP_CLASSID,1);
  if (--((PetscObject)(*ksp))->refct > 0) {*ksp = 0; PetscFunctionReturn(0);}

  
  pc = (*ksp)->pc;
  (*ksp)->pc = PETSC_NULL;
  ierr = KSPReset((*ksp));CHKERRQ(ierr);
  (*ksp)->pc = pc;


   Since KSPDestroy() doesn't need to have  PCReset() called. This doesn't require any special code for users.

   Barry


On Mar 29, 2012, at 10:38 AM, Dmitry Karpeev wrote:

> 
> 
> On Thu, Mar 29, 2012 at 10:13 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> On Thu, Mar 29, 2012 at 08:28, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:
> Back to the original problem: how shall we prevent a shared pc from being gutted by an unprotected PCReset() cascading from a KSPDestroy() on one of the containing ksps?  I can factor out KSPReset_Private()/PCReset_Private() as indicated before, unless there are objections.
> 
>  What do you think of my suggestion of masking ksp->pc when KSPDestroy calls KSPReset? Then KSPReset does not call PCReset if ksp->pc does not exist.
> I guess that works too, but I thought your suggestion applied to userland code right before calling KSPDestroy(&ksp)?
> I suppose that will fix Mark's problem.  Maybe that's the right approach: he got himself into this mess by reusing a pc
> in the inner ksp, he should know how to extricate himself :-)
> 
> Dmitry.
>