Incidentally, any call to XXXReset() is, presumably, to be followed by a call to XXXSetUp(): why not roll the former into the latter? One argument against this would be that in between the calls the user might want to call XXXSetYYY(), which might otherwise be rejected until after XXXReset(), but in this case building a whole new XXX from scratch might be the right thing to do: we are no longer reusing the configuration. Dmitry. On Thu, Mar 29, 2012 at 11:45 AM, Dmitry Karpeev <[email protected]>wrote:

Pushed: http://petsc.cs.iit.edu/petsc/petsc-dev/rev/76f5543c7e89

On Thu, Mar 29, 2012 at 11:07 AM, Barry Smith <[email protected]> wrote:

...

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 <[email protected]>

wrote:

...

On Thu, Mar 29, 2012 at 08:28, Dmitry Karpeev <[email protected]> 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.