src/patches/suse-2.6.27.31/patches.drivers/Out-of-order-tx-frames-was-causing-several-check-con.patch

   1 From 9a24511a01552376ad031ac877b62461d58f6a4d Mon Sep 17 00:00:00 2001
   2 From: Vasu Dev <vasu.dev@intel.com>
   3 Date: Thu, 5 Feb 2009 01:32:29 -0800
   4 References: bnc#473604
   5 Subject: [PATCH] Out of order tx frames was causing several check condition SCSI status
   6  frames followed by these errors in log.
   7
   8         [sdp] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE,SUGGEST_OK
   9         [sdp] Sense Key : Aborted Command [current]
  10         [sdp] Add. Sense: Data phase error
  11
  12 This was causing some test apps to exit due to write failure under heavy
  13 load.
  14
  15 This was due to a race around adding and removing tx frame skb in
  16 fcoe_pending_queue, Chris Leech helped me to find that brief unlocking
  17 period when pulling skb from fcoe_pending_queue in various contexts
  18 (fcoe_watchdog and fcoe_xmit) and then adding skb back into fcoe_pending_queue
  19 up on a failed fcoe_start_io could change skb/tx frame order in
  20 fcoe_pending_queue. Thanks Chris.
  21
  22 This patch allows only single context to pull skb from fcoe_pending_queue
  23 at any time to prevent above described ordering issue/race by use of
  24 fcoe_pending_queue_active flag.
  25
  26 This patch simplified fcoe_watchdog with modified fcoe_check_wait_queue by
  27 use of FCOE_LOW_QUEUE_DEPTH instead previously used several conditionals
  28 to clear and set lp->qfull.
  29
  30 I think FCOE_MAX_QUEUE_DEPTH with FCOE_LOW_QUEUE_DEPTH  will work better
  31 in re/setting lp->qfull and these could be fine tuned for performance.
  32
  33 Signed-off-by: Vasu Dev <vasu.dev@intel.com>
  34 Acked-by: John Jolly <jjolly@suse.de>
  35 ---
  36  drivers/scsi/fcoe/fcoe_sw.c |    1 +
  37  drivers/scsi/fcoe/libfcoe.c |   45 ++++++++++++++++++++----------------------
  38  include/scsi/libfcoe.h      |    1 +
  39  3 files changed, 23 insertions(+), 24 deletions(-)
  40
  41 diff --git a/drivers/scsi/fcoe/fcoe_sw.c b/drivers/scsi/fcoe/fcoe_sw.c
  42 index cf83675..da12c93 100644
  43 --- a/drivers/scsi/fcoe/fcoe_sw.c
  44 +++ b/drivers/scsi/fcoe/fcoe_sw.c
  45 @@ -191,6 +191,7 @@ static int fcoe_sw_netdev_config(struct fc_lport *lp, struct net_device *netdev)
  46
  47
  48         skb_queue_head_init(&fc->fcoe_pending_queue);
  49 +       fc->fcoe_pending_queue_active = 0;
  50
  51         /* setup Source Mac Address */
  52         memcpy(fc->ctl_src_addr, fc->real_dev->dev_addr,
  53 diff --git a/drivers/scsi/fcoe/libfcoe.c b/drivers/scsi/fcoe/libfcoe.c
  54 index 8bc8078..9f8204b 100644
  55 --- a/drivers/scsi/fcoe/libfcoe.c
  56 +++ b/drivers/scsi/fcoe/libfcoe.c
  57 @@ -49,6 +49,7 @@
  58  static int debug_fcoe;
  59
  60  #define FCOE_MAX_QUEUE_DEPTH  256
  61 +#define FCOE_LOW_QUEUE_DEPTH  32
  62
  63  /* destination address mode */
  64  #define FCOE_GW_ADDR_MODE          0x00
  65 @@ -727,21 +728,12 @@ static void fcoe_recv_flogi(struct fcoe_softc *fc, struct fc_frame *fp, u8 *sa)
  66   **/
  67  void fcoe_watchdog(ulong vp)
  68  {
  69 -       struct fc_lport *lp;
  70         struct fcoe_softc *fc;
  71 -       int qfilled = 0;
  72
  73         read_lock(&fcoe_hostlist_lock);
  74         list_for_each_entry(fc, &fcoe_hostlist, list) {
  75 -               lp = fc->lp;
  76 -               if (lp) {
  77 -                       if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)
  78 -                               qfilled = 1;
  79 -                       if (fcoe_check_wait_queue(lp) <  FCOE_MAX_QUEUE_DEPTH) {
  80 -                               if (qfilled)
  81 -                                       lp->qfull = 0;
  82 -                       }
  83 -               }
  84 +               if (fc->lp)
  85 +                       fcoe_check_wait_queue(fc->lp);
  86         }
  87         read_unlock(&fcoe_hostlist_lock);
  88
  89 @@ -757,8 +749,8 @@ void fcoe_watchdog(ulong vp)
  90   *
  91   * This empties the wait_queue, dequeue the head of the wait_queue queue
  92   * and calls fcoe_start_io() for each packet, if all skb have been
  93 - * transmitted, return 0 if a error occurs, then restore wait_queue and
  94 - * try again later.
  95 + * transmitted, return qlen or -1 if a error occurs, then restore
  96 + * wait_queue and  try again later.
  97   *
  98   * The wait_queue is used when the skb transmit fails. skb will go
  99   * in the wait_queue which will be emptied by the time function OR
 100 @@ -768,33 +760,38 @@ void fcoe_watchdog(ulong vp)
 101   **/
 102  static int fcoe_check_wait_queue(struct fc_lport *lp)
 103  {
 104 -       int rc;
 105         struct sk_buff *skb;
 106         struct fcoe_softc *fc;
 107 +       int rc = -1;
 108
 109         fc = fcoe_softc(lp);
 110         spin_lock_bh(&fc->fcoe_pending_queue.lock);
 111
 112 -       /*
 113 -        * if interface pending queue full then set qfull in lport.
 114 -        */
 115 -       if (fc->fcoe_pending_queue.qlen > FCOE_MAX_QUEUE_DEPTH)
 116 -               lp->qfull = 1;
 117 +       if (fc->fcoe_pending_queue_active)
 118 +               goto out;
 119 +       fc->fcoe_pending_queue_active = 1;
 120         if (fc->fcoe_pending_queue.qlen) {
 121                 while ((skb = __skb_dequeue(&fc->fcoe_pending_queue)) != NULL) {
 122                         spin_unlock_bh(&fc->fcoe_pending_queue.lock);
 123                         rc = fcoe_start_io(skb);
 124 -                       if (rc) {
 125 +                       if (rc)
 126                                 fcoe_insert_wait_queue_head(lp, skb);
 127 -                               return rc;
 128 -                       }
 129                         spin_lock_bh(&fc->fcoe_pending_queue.lock);
 130 +                       if (rc)
 131 +                               break;
 132                 }
 133 -               if (fc->fcoe_pending_queue.qlen < FCOE_MAX_QUEUE_DEPTH)
 134 +               /*
 135 +                * if interface pending queue is below FCOE_LOW_QUEUE_DEPTH
 136 +                * then clear qfull flag.
 137 +                */
 138 +               if (fc->fcoe_pending_queue.qlen < FCOE_LOW_QUEUE_DEPTH)
 139                         lp->qfull = 0;
 140         }
 141 +       fc->fcoe_pending_queue_active = 0;
 142 +       rc = fc->fcoe_pending_queue.qlen;
 143 +out:
 144         spin_unlock_bh(&fc->fcoe_pending_queue.lock);
 145 -       return fc->fcoe_pending_queue.qlen;
 146 +       return rc;
 147  }
 148
 149  /**
 150 diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
 151 index 89fdbb9..ab09986 100644
 152 --- a/include/scsi/libfcoe.h
 153 +++ b/include/scsi/libfcoe.h
 154 @@ -46,6 +46,7 @@ struct fcoe_softc {
 155         struct net_device *phys_dev;            /* device with ethtool_ops */
 156         struct packet_type  fcoe_packet_type;
 157         struct sk_buff_head fcoe_pending_queue;
 158 +       u8      fcoe_pending_queue_active;
 159
 160         u8 dest_addr[ETH_ALEN];
 161         u8 ctl_src_addr[ETH_ALEN];
 162 --
 163 1.5.4.5
 164