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linux/drivers/s390/scsi/zfcp_fc.h
Steffen Maier 4da8c5f768 scsi: zfcp: Fix missing auto port scan and thus missing target ports 
Case (1):
  The only waiter on wka_port->completion_wq is zfcp_fc_wka_port_get()
  trying to open a WKA port. As such it should only be woken up by WKA port
  *open* responses, not by WKA port close responses.

Case (2):
  A close WKA port response coming in just after having sent a new open WKA
  port request and before blocking for the open response with wait_event()
  in zfcp_fc_wka_port_get() erroneously renders the wait_event a NOP
  because the close handler overwrites wka_port->status. Hence the
  wait_event condition is erroneously true and it does not enter blocking
  state.

With non-negligible probability, the following time space sequence happens
depending on timing without this fix:

user process        ERP thread zfcp work queue tasklet system work queue
============        ========== =============== ======= =================
$ echo 1 > online
zfcp_ccw_set_online
zfcp_ccw_activate
zfcp_erp_adapter_reopen
msleep scan backoff zfcp_erp_strategy
|                   ...
|                   zfcp_erp_action_cleanup
|                   ...
|                   queue delayed scan_work
|                   queue ns_up_work
|                              ns_up_work:
|                              zfcp_fc_wka_port_get
|                               open wka request
|                                              open response
|                              GSPN FC-GS
|                              RSPN FC-GS [NPIV-only]
|                              zfcp_fc_wka_port_put
|                               (--wka->refcount==0)
|                               sched delayed wka->work
|
~~~Case (1)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zfcp_erp_wait
flush scan_work
|                                                      wka->work:
|                                                      wka->status=CLOSING
|                                                      close wka request
|                              scan_work:
|                              zfcp_fc_wka_port_get
|                               (wka->status==CLOSING)
|                               wka->status=OPENING
|                               open wka request
|                               wait_event
|                               |              close response
|                               |              wka->status=OFFLINE
|                               |              wake_up /*WRONG*/
~~~Case (2)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|                                                      wka->work:
|                                                      wka->status=CLOSING
|                                                      close wka request
zfcp_erp_wait
flush scan_work
|                              scan_work:
|                              zfcp_fc_wka_port_get
|                               (wka->status==CLOSING)
|                               wka->status=OPENING
|                               open wka request
|                                              close response
|                                              wka->status=OFFLINE
|                                              wake_up /*WRONG&NOP*/
|                               wait_event /*NOP*/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|                               (wka->status!=ONLINE)
|                               return -EIO
|                              return early
                                               open response
                                               wka->status=ONLINE
                                               wake_up /*NOP*/

So we erroneously end up with no automatic port scan. This is a big problem
when it happens during boot. The timing is influenced by v3.19 commit
18f87a67e6 ("zfcp: auto port scan resiliency").

Fix it by fully mutually excluding zfcp_fc_wka_port_get() and
zfcp_fc_wka_port_offline(). For that to work, we make the latter block
until we got the response for a close WKA port. In order not to penalize
the system workqueue, we move wka_port->work to our own adapter workqueue.
Note that before v2.6.30 commit 828bc1212a ("[SCSI] zfcp: Set WKA-port to
offline on adapter deactivation"), zfcp did block in
zfcp_fc_wka_port_offline() as well, but with a different condition.

While at it, make non-functional cleanups to improve code reading in
zfcp_fc_wka_port_get(). If we cannot send the WKA port open request, don't
rely on the subsequent wait_event condition to immediately let this case
pass without blocking. Also don't want to rely on the additional condition
handling the refcount to be skipped just to finally return with -EIO.

Link: https://lore.kernel.org/r/20220729162529.1620730-1-maier@linux.ibm.com
Fixes: 5ab944f97e ("[SCSI] zfcp: attach and release SAN nameserver port on demand")
Cc: <stable@vger.kernel.org> #v2.6.28+
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2022-08-01 19:50:00 -04:00

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* zfcp device driver
*
* Fibre Channel related definitions and inline functions for the zfcp
* device driver
*
* Copyright IBM Corp. 2009, 2017
*/
#ifndef ZFCP_FC_H
#define ZFCP_FC_H
#include <scsi/fc/fc_els.h>
#include <scsi/fc/fc_fcp.h>
#include <scsi/fc/fc_ns.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_tcq.h>
#include "zfcp_fsf.h"
#define ZFCP_FC_CT_SIZE_PAGE (PAGE_SIZE - sizeof(struct fc_ct_hdr))
#define ZFCP_FC_GPN_FT_ENT_PAGE (ZFCP_FC_CT_SIZE_PAGE \
/ sizeof(struct fc_gpn_ft_resp))
#define ZFCP_FC_GPN_FT_NUM_BUFS 4 /* memory pages */
#define ZFCP_FC_GPN_FT_MAX_SIZE (ZFCP_FC_GPN_FT_NUM_BUFS * PAGE_SIZE \
- sizeof(struct fc_ct_hdr))
#define ZFCP_FC_GPN_FT_MAX_ENT (ZFCP_FC_GPN_FT_NUM_BUFS * \
(ZFCP_FC_GPN_FT_ENT_PAGE + 1))
#define ZFCP_FC_CTELS_TMO (2 * FC_DEF_R_A_TOV / 1000)
/**
* struct zfcp_fc_event - FC HBAAPI event for internal queueing from irq context
* @code: Event code
* @data: Event data
* @list: list_head for zfcp_fc_events list
*/
struct zfcp_fc_event {
enum fc_host_event_code code;
u32 data;
struct list_head list;
};
/**
* struct zfcp_fc_events - Infrastructure for posting FC events from irq context
* @list: List for queueing of events from irq context to workqueue
* @list_lock: Lock for event list
* @work: work_struct for forwarding events in workqueue
*/
struct zfcp_fc_events {
struct list_head list;
spinlock_t list_lock;
struct work_struct work;
};
/**
* struct zfcp_fc_gid_pn_req - container for ct header plus gid_pn request
* @ct_hdr: FC GS common transport header
* @gid_pn: GID_PN request
*/
struct zfcp_fc_gid_pn_req {
struct fc_ct_hdr ct_hdr;
struct fc_ns_gid_pn gid_pn;
} __packed;
/**
* struct zfcp_fc_gid_pn_rsp - container for ct header plus gid_pn response
* @ct_hdr: FC GS common transport header
* @gid_pn: GID_PN response
*/
struct zfcp_fc_gid_pn_rsp {
struct fc_ct_hdr ct_hdr;
struct fc_gid_pn_resp gid_pn;
} __packed;
/**
* struct zfcp_fc_gpn_ft - container for ct header plus gpn_ft request
* @ct_hdr: FC GS common transport header
* @gpn_ft: GPN_FT request
*/
struct zfcp_fc_gpn_ft_req {
struct fc_ct_hdr ct_hdr;
struct fc_ns_gid_ft gpn_ft;
} __packed;
/**
* struct zfcp_fc_gspn_req - container for ct header plus GSPN_ID request
* @ct_hdr: FC GS common transport header
* @gspn: GSPN_ID request
*/
struct zfcp_fc_gspn_req {
struct fc_ct_hdr ct_hdr;
struct fc_gid_pn_resp gspn;
} __packed;
/**
* struct zfcp_fc_gspn_rsp - container for ct header plus GSPN_ID response
* @ct_hdr: FC GS common transport header
* @gspn: GSPN_ID response
* @name: The name string of the GSPN_ID response
*/
struct zfcp_fc_gspn_rsp {
struct fc_ct_hdr ct_hdr;
struct fc_gspn_resp gspn;
char name[FC_SYMBOLIC_NAME_SIZE];
} __packed;
/**
* struct zfcp_fc_rspn_req - container for ct header plus RSPN_ID request
* @ct_hdr: FC GS common transport header
* @rspn: RSPN_ID request
* @name: The name string of the RSPN_ID request
*/
struct zfcp_fc_rspn_req {
struct fc_ct_hdr ct_hdr;
struct fc_ns_rspn rspn;
char name[FC_SYMBOLIC_NAME_SIZE];
} __packed;
/**
* struct zfcp_fc_req - Container for FC ELS and CT requests sent from zfcp
* @ct_els: data required for issuing fsf command
* @sg_req: scatterlist entry for request data, refers to embedded @u submember
* @sg_rsp: scatterlist entry for response data, refers to embedded @u submember
* @u: request and response specific data
* @u.adisc: ADISC specific data
* @u.adisc.req: ADISC request
* @u.adisc.rsp: ADISC response
* @u.gid_pn: GID_PN specific data
* @u.gid_pn.req: GID_PN request
* @u.gid_pn.rsp: GID_PN response
* @u.gpn_ft: GPN_FT specific data
* @u.gpn_ft.sg_rsp2: GPN_FT response, not embedded here, allocated elsewhere
* @u.gpn_ft.req: GPN_FT request
* @u.gspn: GSPN specific data
* @u.gspn.req: GSPN request
* @u.gspn.rsp: GSPN response
* @u.rspn: RSPN specific data
* @u.rspn.req: RSPN request
* @u.rspn.rsp: RSPN response
*/
struct zfcp_fc_req {
struct zfcp_fsf_ct_els ct_els;
struct scatterlist sg_req;
struct scatterlist sg_rsp;
union {
struct {
struct fc_els_adisc req;
struct fc_els_adisc rsp;
} adisc;
struct {
struct zfcp_fc_gid_pn_req req;
struct zfcp_fc_gid_pn_rsp rsp;
} gid_pn;
struct {
struct scatterlist sg_rsp2[ZFCP_FC_GPN_FT_NUM_BUFS - 1];
struct zfcp_fc_gpn_ft_req req;
} gpn_ft;
struct {
struct zfcp_fc_gspn_req req;
struct zfcp_fc_gspn_rsp rsp;
} gspn;
struct {
struct zfcp_fc_rspn_req req;
struct fc_ct_hdr rsp;
} rspn;
} u;
};
/**
* enum zfcp_fc_wka_status - FC WKA port status in zfcp
* @ZFCP_FC_WKA_PORT_OFFLINE: Port is closed and not in use
* @ZFCP_FC_WKA_PORT_CLOSING: The FSF "close port" request is pending
* @ZFCP_FC_WKA_PORT_OPENING: The FSF "open port" request is pending
* @ZFCP_FC_WKA_PORT_ONLINE: The port is open and the port handle is valid
*/
enum zfcp_fc_wka_status {
ZFCP_FC_WKA_PORT_OFFLINE,
ZFCP_FC_WKA_PORT_CLOSING,
ZFCP_FC_WKA_PORT_OPENING,
ZFCP_FC_WKA_PORT_ONLINE,
};
/**
* struct zfcp_fc_wka_port - representation of well-known-address (WKA) FC port
* @adapter: Pointer to adapter structure this WKA port belongs to
* @opened: Wait for completion of open command
* @closed: Wait for completion of close command
* @status: Current status of WKA port
* @refcount: Reference count to keep port open as long as it is in use
* @d_id: FC destination id or well-known-address
* @handle: FSF handle for the open WKA port
* @mutex: Mutex used during opening/closing state changes
* @work: For delaying the closing of the WKA port
*/
struct zfcp_fc_wka_port {
struct zfcp_adapter *adapter;
wait_queue_head_t opened;
wait_queue_head_t closed;
enum zfcp_fc_wka_status status;
atomic_t refcount;
u32 d_id;
u32 handle;
struct mutex mutex;
struct delayed_work work;
};
/**
* struct zfcp_fc_wka_ports - Data structures for FC generic services
* @ms: FC Management service
* @ts: FC time service
* @ds: FC directory service
* @as: FC alias service
*/
struct zfcp_fc_wka_ports {
struct zfcp_fc_wka_port ms;
struct zfcp_fc_wka_port ts;
struct zfcp_fc_wka_port ds;
struct zfcp_fc_wka_port as;
};
/**
* zfcp_fc_scsi_to_fcp - setup FCP command with data from scsi_cmnd
* @fcp: fcp_cmnd to setup
* @scsi: scsi_cmnd where to get LUN, task attributes/flags and CDB
*/
static inline
void zfcp_fc_scsi_to_fcp(struct fcp_cmnd *fcp, struct scsi_cmnd *scsi)
{
u32 datalen;
int_to_scsilun(scsi->device->lun, (struct scsi_lun *) &fcp->fc_lun);
fcp->fc_pri_ta = FCP_PTA_SIMPLE;
if (scsi->sc_data_direction == DMA_FROM_DEVICE)
fcp->fc_flags |= FCP_CFL_RDDATA;
if (scsi->sc_data_direction == DMA_TO_DEVICE)
fcp->fc_flags |= FCP_CFL_WRDATA;
memcpy(fcp->fc_cdb, scsi->cmnd, scsi->cmd_len);
datalen = scsi_bufflen(scsi);
fcp->fc_dl = cpu_to_be32(datalen);
if (scsi_get_prot_type(scsi) == SCSI_PROT_DIF_TYPE1) {
datalen += datalen / scsi->device->sector_size * 8;
fcp->fc_dl = cpu_to_be32(datalen);
}
}
/**
* zfcp_fc_fcp_tm() - Setup FCP command as task management command.
* @fcp: Pointer to FCP_CMND IU to set up.
* @dev: Pointer to SCSI_device where to send the task management command.
* @tm_flags: Task management flags to setup tm command.
*/
static inline
void zfcp_fc_fcp_tm(struct fcp_cmnd *fcp, struct scsi_device *dev, u8 tm_flags)
{
int_to_scsilun(dev->lun, (struct scsi_lun *) &fcp->fc_lun);
fcp->fc_tm_flags = tm_flags;
}
/**
* zfcp_fc_evap_fcp_rsp - evaluate FCP RSP IU and update scsi_cmnd accordingly
* @fcp_rsp: FCP RSP IU to evaluate
* @scsi: SCSI command where to update status and sense buffer
*/
static inline
void zfcp_fc_eval_fcp_rsp(struct fcp_resp_with_ext *fcp_rsp,
struct scsi_cmnd *scsi)
{
struct fcp_resp_rsp_info *rsp_info;
char *sense;
u32 sense_len, resid;
u8 rsp_flags;
scsi->result |= fcp_rsp->resp.fr_status;
rsp_flags = fcp_rsp->resp.fr_flags;
if (unlikely(rsp_flags & FCP_RSP_LEN_VAL)) {
rsp_info = (struct fcp_resp_rsp_info *) &fcp_rsp[1];
if (rsp_info->rsp_code == FCP_TMF_CMPL)
set_host_byte(scsi, DID_OK);
else {
set_host_byte(scsi, DID_ERROR);
return;
}
}
if (unlikely(rsp_flags & FCP_SNS_LEN_VAL)) {
sense = (char *) &fcp_rsp[1];
if (rsp_flags & FCP_RSP_LEN_VAL)
sense += be32_to_cpu(fcp_rsp->ext.fr_rsp_len);
sense_len = min_t(u32, be32_to_cpu(fcp_rsp->ext.fr_sns_len),
SCSI_SENSE_BUFFERSIZE);
memcpy(scsi->sense_buffer, sense, sense_len);
}
if (unlikely(rsp_flags & FCP_RESID_UNDER)) {
resid = be32_to_cpu(fcp_rsp->ext.fr_resid);
scsi_set_resid(scsi, resid);
if (scsi_bufflen(scsi) - resid < scsi->underflow &&
!(rsp_flags & FCP_SNS_LEN_VAL) &&
fcp_rsp->resp.fr_status == SAM_STAT_GOOD)
set_host_byte(scsi, DID_ERROR);
} else if (unlikely(rsp_flags & FCP_RESID_OVER)) {
/* FCP_DL was not sufficient for SCSI data length */
if (fcp_rsp->resp.fr_status == SAM_STAT_GOOD)
set_host_byte(scsi, DID_ERROR);
}
}
#endif
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