zfcp: retrieve local RDP data, fix and cleanup

Hello all,

this is the second version of my RDP patchset for zfcp, after I noticed a memory-leak in the first version earlier this year. Here is the original description, which remains valid:

With FC-LS-3 Fibre Channel got support for the RDP Extended Link Service, which we can use to gather diagnostics data (health values from the optics and such). To gather those data from our local link, the FCP Channel firmware (for FCP and Ficon Express adapters) added some new fields in our Exchange Port Data firmware command (primarily SFP data).
This patchset adds a new sysfs-directory below our
adapter-object and several files in that to read those new fields.
Additionally this also adds a file to read the buffer-to-buffer
credit value from our local port (also something that can be gathered using the RDP ELS).

The main purpose of the data from RDP requests (at least in my mind) are to catch some otherwise hard to track down errors, like dirt on the fibre and such (I would expect optics data to degraded with such conditions). These things are a pain to track down because it doesn't cause the link to go away, just some sporadic errors that can result in incomplete exchanges and such.

The patchset is somewhat big because I don't want to issue a single Exchange Port/Config Data command for each read of those files, which would generate unnecessary traffic (and possibly inconsistent data) on our command-queue (we don't have an admin-queue or some such). So it also adds a (time-based) mechanism to cache data from Exchange Config/Port Data.
We also want to prevent our adapter-structure from growing,
which would further grow Scsi_Host, which is already too damn big, so these data are decoupled.

More details are in the patches themselves.

Additionally to this, there are two more patches from Steffen that we want to include, the first (patch 10) is just a cleanup for better readability, the second (patch 11) is a fix/improvement for our tracing-feature to make traces of failed FCP requests better. Even though Steffen flagged the later as fix, I don't think we need extra handling for it, if it goes in with the rest, thats fine - its nothing pressing.

Reviews are highly welcome :-).

James, Martin, if there are no objections, it would be nice if you could still include this in the merge for 5.5.

FYI: I also plan to/am in the middle of writing a simple command-line
tool to send RDP to all/certain available remote/local FC-Ports in the System and present them in a sane format (sane to me ;-) ). This could be used for logging, or while gathering debug-data from a system.

The RDP ELS' to remote ports will be send using BSG. Local data (for zFCP) would be read using this new interface.

If anyone is interested, I can point it out on the list once I have something that has at least a minimum set of functionality.

Benjamin Block (9):
zfcp: signal incomplete or error for sync exchange config/port data
zfcp: diagnostics buffer caching and use for exchange port data
zfcp: add diagnostics buffer for exchange config data
zfcp: support retrieval of SFP Data via Exchange Port Data
zfcp: introduce SysFS interface for diagnostics of local SFP
transceiver
zfcp: implicitly refresh port-data diagnostics when reading SysFS
zfcp: introduce SysFS interface to read the local B2B-Credit
zfcp: implicitly refresh config-data diagnostics when reading SysFS
zfcp: move maximum age of diagnostic buffers into a per-adapter
variable

Steffen Maier (2):
zfcp: proper indentation to reduce confusion in zfcp_erp_required_act
zfcp: trace channel log even for FCP command responses

 drivers/s390/scsi/Makefile     |   2 +-
 drivers/s390/scsi/zfcp_aux.c   |  12 +-
 drivers/s390/scsi/zfcp_dbf.c   |   8 +-
 drivers/s390/scsi/zfcp_def.h   |   4 +-
 drivers/s390/scsi/zfcp_diag.c  | 305 +++++++++++++++++++++++++++++++++
 drivers/s390/scsi/zfcp_diag.h  | 101 +++++++++++
 drivers/s390/scsi/zfcp_erp.c   |   4 +-
 drivers/s390/scsi/zfcp_ext.h   |   1 +
 drivers/s390/scsi/zfcp_fsf.c   |  73 +++++++-
 drivers/s390/scsi/zfcp_fsf.h   |  21 ++-
 drivers/s390/scsi/zfcp_scsi.c  |   4 +-
 drivers/s390/scsi/zfcp_sysfs.c | 170 +++++++++++++++++-
 12 files changed, 683 insertions(+), 22 deletions(-)
 create mode 100644 drivers/s390/scsi/zfcp_diag.c
 create mode 100644 drivers/s390/scsi/zfcp_diag.h

2.21.0