src/patches/suse-2.6.27.39/patches.drivers/libfc-updated-comment-for-orde.diff

   1 From: Vasu Dev <vasu.dev@intel.com>
   2 Subject: [FcOE] updated comment for order of em and ex locks
   3 References: bnc #459142
   4
   5 The fc_exch is public but em_lock is static to fc_exch.c,
   6 so updated comment only in fc_exch.c on order of these locks.
   7
   8 Also removed seq.f_ctl from comments since this field is
   9 already removed.
  10
  11 Signed-off-by: Vasu Dev <vasu.dev@intel.com>
  12 Acked-by: Bernhard Walle <bwalle@suse.de>
  13 ---
  14
  15  drivers/scsi/libfc/fc_exch.c |    5 ++++-
  16  include/scsi/libfc.h         |    5 ++---
  17  2 files changed, 6 insertions(+), 4 deletions(-)
  18
  19
  20 --- a/drivers/scsi/libfc/fc_exch.c
  21 +++ b/drivers/scsi/libfc/fc_exch.c
  22 @@ -68,7 +68,8 @@ static struct kmem_cache *fc_em_cachep;
  23   */
  24  struct fc_exch_mgr {
  25         enum fc_class   class;          /* default class for sequences */
  26 -       spinlock_t      em_lock;        /* exchange manager lock */
  27 +       spinlock_t      em_lock;        /* exchange manager lock,
  28 +                                          must be taken before ex_lock */
  29         u16             last_xid;       /* last allocated exchange ID */
  30         u16             min_xid;        /* min exchange ID */
  31         u16             max_xid;        /* max exchange ID */
  32 @@ -179,6 +180,8 @@ static struct fc_seq *fc_seq_start_next_
  33   * sequence allocation and deallocation must be locked.
  34   *  - exchange refcnt can be done atomicly without locks.
  35   *  - sequence allocation must be locked by exch lock.
  36 + *  - If the em_lock and ex_lock must be taken at the same time, then the
  37 + *    em_lock must be taken before the ex_lock.
  38   */
  39
  40  /*
  41 --- a/include/scsi/libfc.h
  42 +++ b/include/scsi/libfc.h
  43 @@ -299,11 +299,10 @@ struct fc_seq {
  44  /*
  45   * Exchange.
  46   *
  47 - * Locking notes: The ex_lock protects changes to the following fields:
  48 - *     esb_stat, f_ctl, seq.ssb_stat, seq.f_ctl.
  49 + * Locking notes: The ex_lock protects following items:
  50 + *     state, esb_stat, f_ctl, seq.ssb_stat
  51   *     seq_id
  52   *     sequence allocation
  53 - *
  54   */
  55  struct fc_exch {
  56         struct fc_exch_mgr *em;         /* exchange manager */