[ofw] RE: correctly handle IOU manager destruction without ASSERT firing.

[Smith, Stan]

Leonid Keller wrote:
> OK with me.

Applied in svn.2102

Stan.

>
>> -----Original Message-----
>> From: Smith, Stan [mailto:stan.smith at intel.com]
>> Sent: Wednesday, April 15, 2009 2:47 AM
>> To: Leonid Keller
>> Cc: ofw at lists.openfabrics.org
>> Subject: correctly handle IOU manager destruction without
>> ASSERT firing.
>>
>>
>> Hello Leonid,
>>   While testing your ibbus.sys ControlDeviceObject code, on
>> HCA disable attempts I kept hitting an al_common.c ASSERT()
>> which was triggered by calling deref_al_obj(
>> &p_ext->h_ca->obj ); @ line #423 in bus_iou_mgr.c:free_iou_mgr().
>> The ASSERT() fired due to the fact the AL object
>> p_ext->h_ca->obj was in an incorrect CL_STATE; already in the
>> CL_DESTROYED state, ref_cnt == 0, already destroyed?
>>
>> The issue was traced back to iou_mgr_iou_remove() where the
>> p_ext->h_ca field was never set to NULL after the last IOU
>> PDO removal.  A non-NULL h_ca field allowed free_iou_mgr() to
>> attempt an extra deref_al_obj() on an object which had
>> already been destroyed by virtue of it's ref_cnt going to
>> zero from the deref_al_obj() call in iou_mgr_remove().
>>
>> Fix - NULL out the h_ca field when removing the last IOU PDO.
>> Additionally, extraenous debug code is removed.
>>
>> If you approve, I will svn commit.
>>
>> Thank you,
>>
>> Stan.
>>
>>
>> Signed off by stan.smith at intel.com
>>
>> diff U3 C:/Documents and Settings/scsmith/Local
>> Settings/Temp/bus_iou_mgr.c-revBASE.svn000.tmp.c C:/Documents
>> and Settings/scsmith/My
>> Documents/openIB-windows/SVN/gen1/trunk/core/bus/kernel/bus_iou_mgr.c
>> --- bus_iou_mgr.c-revBASE.svn000.tmp.c  Tue Apr 14 16:22:16 2009
>> +++ core/bus/kernel/bus_iou_mgr.c       Tue Apr 14 16:02:11 2009 @@
>>                                         -426,11 +426,6 @@
>> p_bfi->whoami,
>> p_ext->cl_ext.vfptr_pnp_po->identity,
>>
>> p_ext->cl_ext.p_self_do, p_ext ) );
>>
>> -               BUS_TRACE( BUS_DBG_PNP,("%s
>> p_ext->h_ca->obj.state %d ref_cnt %d\n",
>> -                                       p_bfi->whoami,
>> -                                       p_ext->h_ca->obj.state,
>> -                                       p_ext->h_ca->obj.ref_cnt)); -
>>                 IoDeleteDevice( p_ext->cl_ext.p_self_do );         }
>>
>> @@ -868,7 +863,8 @@
>>                         p_ext->cl_ext.vfptr_pnp_po->identity,
>>                         p_ext->cl_ext.p_self_do, p_ext,
>>                         p_ext->b_present, p_ext->b_reported_missing,
>> p_ext->b_hibernating ) );
>> -               goto hca_deref;
>> +               deref_al_obj( &p_ext->h_ca->obj );
>> +               goto xit;
>>         }
>>
>>         p_ext->b_present = FALSE;
>> @@ -890,9 +886,10 @@
>>         /* free PNP context */
>>         cl_free( p_ctx );
>>         p_pnp_rec->pnp_rec.context = NULL;
>> -
>> -hca_deref:
>>         deref_al_obj( &p_ext->h_ca->obj );
>> +       p_ext->h_ca = NULL;     // for free_iou_mgr() +
>> +xit:
>>         cl_mutex_release( &gp_iou_mgr->pdo_mutex );
>>
>>         BUS_EXIT( BUS_DBG_PNP );