When a sequence cannot be delivered to the target, the local
port will schedule retries, While this process is in progress,
if we destroy the FCoE interface, the fcoe_sw_destroy routine is
entered, and the fc_exch_mgr_free(lp->emp) is called.  Thus
if fc_exch_alloc() is called when retrying the sequence,
the mempool_alloc() will fail to allocate the exchange because
the mempool of the exchange manager has already been released.
This patch is to cancel any pending retry work of the local
port before we start to destroy the interface.

Also, when resetting the local port, we should also stop the
scheduled pending retries.
Signed-off-by: NSteve Ma <steve.ma@intel.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

The fcoe_xmit could call fc_pause in case the pending skb queue len is larger
than FCOE_MAX_QUEUE_DEPTH, the fc_pause was trying to grab lport->lp_muex to
change lport->link_status and that had these issues :-

1. The fcoe_xmit was getting called with bh disabled, thus causing
"BUG: scheduling while atomic" when grabbing lport->lp_muex with bh disabled.

2. fc_linkup and fc_linkdown function calls lport_enter function with
lport->lp_mutex held and these enter function in turn calls fcoe_xmit to send
lport related FC frame, e.g. fc_linkup => fc_lport_enter_flogi to send flogi
req. In this case grabbing the same lport->lp_mutex again in fc_puase from
fcoe_xmit would cause deadlock.

The lport->lp_mutex was used for setting FC_PAUSE in fcoe_xmit path but
FC_PAUSE bit was not used anywhere beside just setting and clear this
bit in lport->link_status, instead used a separate field qfull in fc_lport
to eliminate need for lport->lp_mutex to track pending queue full condition
and in turn avoid above described two locking issues.

Also added check for lp->qfull in fc_fcp_lport_queue_ready to trigger
SCSI_MLQUEUE_HOST_BUSY when lp->qfull is set to prevent more scsi-ml cmds
while lp->qfull is set.

This patch eliminated FC_LINK_UP and FC_PAUSE and instead used dedicated
fields in fc_lport for this, this simplified all related conditional
code.

Also removed fc_pause and fc_unpause functions and instead used newly added
lport->qfull directly in fcoe.
Signed-off-by: NVasu Dev <vasu.dev@intel.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

fc_exch_mgr structure is private to fc_exch.c. To export exch_mgr_reset to
transport, transport needs access to the exch manager. Change
exch_mgr_reset to use lport param which is the shared structure between
libFC and transport.

Alternatively, fc_exch_mgr definition can be moved to libfc.h so that lport
can be accessed from mp*.
Signed-off-by: NAbhijeet Joglekar <abjoglek@cisco.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

libFC is composed of 4 blocks supported by an exchange manager
and a framing library. The upper 4 layers are fc_lport, fc_disc,
fc_rport and fc_fcp. A LLD that uses libfc could choose to
either use libfc's block, or using the transport template
defined in libfc.h, override one or more blocks with its own
implementation.

The EM (Exchange Manager) manages exhcanges/sequences for all
commands- ELS, CT and FCP.

The framing library frames ELS and CT commands.

The fc_lport block manages the library's representation of the
host's FC enabled ports.

The fc_disc block manages discovery of targets as well as
handling changes that occur in the FC fabric (via. RSCN events).

The fc_rport block manages the library's representation of other
entities in the FC fabric. Currently the library uses this block
for targets, its peer when in point-to-point mode and the
directory server, but can be extended for other entities if
needed.

The fc_fcp block interacts with the scsi-ml and handles all
I/O.
Signed-off-by: NRobert Love <robert.w.love@intel.com>
[jejb: added include of delay.h to fix ppc64 compile prob spotted by sfr]
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>