src/patches/suse-2.6.27.39/patches.arch/s390-15-04-zfcp-unchained-sbals.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: zfcp: Use only single SBAL commands from recovery
   3 References: bnc#518291,LTC#54462
   4
   5 Symptom:     Issuing an ELS request might not detect a stalled
   6              outbound queue
   7 Problem:     zfcp uses chained SBALs for ELS requests leading to the
   8              situation that the ELS request gets one free SBAL, but
   9              not the following ones. In this situation the ELS request
  10              fails but does not trigger the error handling for the
  11              stalled queue.
  12 Solution:    Use unchained SBALs where possible, especially for
  13              commands from the erp. This guarantees that each erp
  14              command will get the required SBAL or trigger queue
  15              recovery.
  16
  17 Acked-by: John Jolly <jjolly@suse.de>
  18 ---
  19  drivers/s390/scsi/zfcp_fsf.c |   33 +++++++++++++++++++++++++--------
  20  1 file changed, 25 insertions(+), 8 deletions(-)
  21
  22 --- a/drivers/s390/scsi/zfcp_fsf.c      2009-07-01 12:26:28.000000000 +0200
  23 +++ b/drivers/s390/scsi/zfcp_fsf.c      2009-07-01 12:28:43.000000000 +0200
  24 @@ -1012,6 +1012,23 @@ skip_fsfstatus:
  25                 send_ct->handler(send_ct->handler_data);
  26  }
  27
  28 +static void zfcp_fsf_setup_ct_els_unchained(struct qdio_buffer_element *sbale,
  29 +                                           struct scatterlist *sg_req,
  30 +                                           struct scatterlist *sg_resp)
  31 +{
  32 +       sbale[0].flags |= SBAL_FLAGS0_TYPE_WRITE_READ;
  33 +       sbale[2].addr   = sg_virt(sg_req);
  34 +       sbale[2].length = sg_req->length;
  35 +       sbale[3].addr   = sg_virt(sg_resp);
  36 +       sbale[3].length = sg_resp->length;
  37 +       sbale[3].flags |= SBAL_FLAGS_LAST_ENTRY;
  38 +}
  39 +
  40 +static int zfcp_fsf_one_sbal(struct scatterlist *sg)
  41 +{
  42 +        return sg_is_last(sg) && sg->length <= PAGE_SIZE;
  43 +}
  44 +
  45  static int zfcp_fsf_setup_ct_els_sbals(struct zfcp_fsf_req *req,
  46                                        struct scatterlist *sg_req,
  47                                        struct scatterlist *sg_resp,
  48 @@ -1022,16 +1039,16 @@ static int zfcp_fsf_setup_ct_els_sbals(s
  49         int bytes;
  50
  51         if (!(feat & FSF_FEATURE_ELS_CT_CHAINED_SBALS)) {
  52 -               if (sg_req->length > PAGE_SIZE || sg_resp->length > PAGE_SIZE ||
  53 -                   !sg_is_last(sg_req) || !sg_is_last(sg_resp))
  54 +               if (!zfcp_fsf_one_sbal(sg_req) || !zfcp_fsf_one_sbal(sg_resp))
  55                         return -EOPNOTSUPP;
  56
  57 -               sbale[0].flags |= SBAL_FLAGS0_TYPE_WRITE_READ;
  58 -               sbale[2].addr   = sg_virt(sg_req);
  59 -               sbale[2].length = sg_req->length;
  60 -               sbale[3].addr   = sg_virt(sg_resp);
  61 -               sbale[3].length = sg_resp->length;
  62 -               sbale[3].flags |= SBAL_FLAGS_LAST_ENTRY;
  63 +               zfcp_fsf_setup_ct_els_unchained(sbale, sg_req, sg_resp);
  64 +               return 0;
  65 +       }
  66 +
  67 +       /* use single, unchained SBAL if it can hold the request */
  68 +       if (zfcp_fsf_one_sbal(sg_req) && zfcp_fsf_one_sbal(sg_resp)) {
  69 +               zfcp_fsf_setup_ct_els_unchained(sbale, sg_req, sg_resp);
  70                 return 0;
  71         }
  72