releases/3.10.88/libfc-fix-fc_fcp_cleanup_each_cmd.patch

   1 From 8f2777f53e3d5ad8ef2a176a4463a5c8e1a16431 Mon Sep 17 00:00:00 2001
   2 From: Bart Van Assche <bart.vanassche@sandisk.com>
   3 Date: Fri, 5 Jun 2015 14:20:51 -0700
   4 Subject: libfc: Fix fc_fcp_cleanup_each_cmd()
   5
   6 From: Bart Van Assche <bart.vanassche@sandisk.com>
   7
   8 commit 8f2777f53e3d5ad8ef2a176a4463a5c8e1a16431 upstream.
   9
  10 Since fc_fcp_cleanup_cmd() can sleep this function must not
  11 be called while holding a spinlock. This patch avoids that
  12 fc_fcp_cleanup_each_cmd() triggers the following bug:
  13
  14 BUG: scheduling while atomic: sg_reset/1512/0x00000202
  15 1 lock held by sg_reset/1512:
  16  #0:  (&(&fsp->scsi_pkt_lock)->rlock){+.-...}, at: [<ffffffffc0225cd5>] fc_fcp_cleanup_each_cmd.isra.21+0xa5/0x150 [libfc]
  17 Preemption disabled at:[<ffffffffc0225cd5>] fc_fcp_cleanup_each_cmd.isra.21+0xa5/0x150 [libfc]
  18 Call Trace:
  19  [<ffffffff816c612c>] dump_stack+0x4f/0x7b
  20  [<ffffffff810828bc>] __schedule_bug+0x6c/0xd0
  21  [<ffffffff816c87aa>] __schedule+0x71a/0xa10
  22  [<ffffffff816c8ad2>] schedule+0x32/0x80
  23  [<ffffffffc0217eac>] fc_seq_set_resp+0xac/0x100 [libfc]
  24  [<ffffffffc0218b11>] fc_exch_done+0x41/0x60 [libfc]
  25  [<ffffffffc0225cff>] fc_fcp_cleanup_each_cmd.isra.21+0xcf/0x150 [libfc]
  26  [<ffffffffc0225f43>] fc_eh_device_reset+0x1c3/0x270 [libfc]
  27  [<ffffffff814a2cc9>] scsi_try_bus_device_reset+0x29/0x60
  28  [<ffffffff814a3908>] scsi_ioctl_reset+0x258/0x2d0
  29  [<ffffffff814a2650>] scsi_ioctl+0x150/0x440
  30  [<ffffffff814b3a9d>] sd_ioctl+0xad/0x120
  31  [<ffffffff8132f266>] blkdev_ioctl+0x1b6/0x810
  32  [<ffffffff811da608>] block_ioctl+0x38/0x40
  33  [<ffffffff811b4e08>] do_vfs_ioctl+0x2f8/0x530
  34  [<ffffffff811b50c1>] SyS_ioctl+0x81/0xa0
  35  [<ffffffff816cf8b2>] system_call_fastpath+0x16/0x7a
  36
  37 Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
  38 Signed-off-by: Vasu Dev <vasu.dev@intel.com>
  39 Signed-off-by: James Bottomley <JBottomley@Odin.com>
  40 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  41
  42 ---
  43  drivers/scsi/libfc/fc_fcp.c |   19 +++++++++++++++++--
  44  1 file changed, 17 insertions(+), 2 deletions(-)
  45
  46 --- a/drivers/scsi/libfc/fc_fcp.c
  47 +++ b/drivers/scsi/libfc/fc_fcp.c
  48 @@ -1039,11 +1039,26 @@ restart:
  49                 fc_fcp_pkt_hold(fsp);
  50                 spin_unlock_irqrestore(&si->scsi_queue_lock, flags);
  51
  52 -               if (!fc_fcp_lock_pkt(fsp)) {
  53 +               spin_lock_bh(&fsp->scsi_pkt_lock);
  54 +               if (!(fsp->state & FC_SRB_COMPL)) {
  55 +                       fsp->state |= FC_SRB_COMPL;
  56 +                       /*
  57 +                        * TODO: dropping scsi_pkt_lock and then reacquiring
  58 +                        * again around fc_fcp_cleanup_cmd() is required,
  59 +                        * since fc_fcp_cleanup_cmd() calls into
  60 +                        * fc_seq_set_resp() and that func preempts cpu using
  61 +                        * schedule. May be schedule and related code should be
  62 +                        * removed instead of unlocking here to avoid scheduling
  63 +                        * while atomic bug.
  64 +                        */
  65 +                       spin_unlock_bh(&fsp->scsi_pkt_lock);
  66 +
  67                         fc_fcp_cleanup_cmd(fsp, error);
  68 +
  69 +                       spin_lock_bh(&fsp->scsi_pkt_lock);
  70                         fc_io_compl(fsp);
  71 -                       fc_fcp_unlock_pkt(fsp);
  72                 }
  73 +               spin_unlock_bh(&fsp->scsi_pkt_lock);
  74
  75                 fc_fcp_pkt_release(fsp);
  76                 spin_lock_irqsave(&si->scsi_queue_lock, flags);