[SCSI] zfcp: Replace fsf_req wait_queue with completion

The combination wait_queue/wakeup in conjunction with the flag
ZFCP_STATUS_FSFREQ_COMPLETED to signal the completion of an fsfreq
was not race-safe and can be better solved by a completion.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index c1becfc..944f677 100644 (file)
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -248,7 +248,6 @@ enum zfcp_wka_status {
 
 /* FSF request status (this does not have a common part) */
 #define ZFCP_STATUS_FSFREQ_TASK_MANAGEMENT     0x00000002
-#define ZFCP_STATUS_FSFREQ_COMPLETED           0x00000004
 #define ZFCP_STATUS_FSFREQ_ERROR               0x00000008
 #define ZFCP_STATUS_FSFREQ_CLEANUP             0x00000010
 #define ZFCP_STATUS_FSFREQ_ABORTSUCCEEDED      0x00000040
@@ -532,7 +531,7 @@ struct zfcp_fsf_req {
        u8                     sbale_curr;     /* current SBALE during creation
                                                  of request */
        u8                      sbal_response;  /* SBAL used in interrupt */
-       wait_queue_head_t      completion_wq;  /* can be used by a routine
+       struct completion       completion;     /* can be used by a routine
                                                  to wait for completion */
        u32                     status;        /* status of this request */
        u32                    fsf_command;    /* FSF Command copy */

diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 39e4dd1..a377e2f 100644 (file)
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -485,8 +485,7 @@ static void zfcp_erp_strategy_check_fsfreq(struct zfcp_erp_action *act)
                }
                if (act->status & ZFCP_STATUS_ERP_TIMEDOUT)
                        zfcp_rec_dbf_event_action("erscf_2", act);
-               if (act->fsf_req->status & (ZFCP_STATUS_FSFREQ_COMPLETED |
-                                           ZFCP_STATUS_FSFREQ_DISMISSED))
+               if (act->fsf_req->status & ZFCP_STATUS_FSFREQ_DISMISSED)
                        act->fsf_req = NULL;
        } else
                act->fsf_req = NULL;

diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index 7ca2995..ed06a1d 100644 (file)
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -444,23 +444,11 @@ static void zfcp_fsf_req_complete(struct zfcp_fsf_req *req)
 
        if (req->erp_action)
                zfcp_erp_notify(req->erp_action, 0);
-       req->status |= ZFCP_STATUS_FSFREQ_COMPLETED;
 
        if (likely(req->status & ZFCP_STATUS_FSFREQ_CLEANUP))
                zfcp_fsf_req_free(req);
        else
-       /* notify initiator waiting for the requests completion */
-       /*
-        * FIXME: Race! We must not access fsf_req here as it might have been
-        * cleaned up already due to the set ZFCP_STATUS_FSFREQ_COMPLETED
-        * flag. It's an improbable case. But, we have the same paranoia for
-        * the cleanup flag already.
-        * Might better be handled using complete()?
-        * (setting the flag and doing wakeup ought to be atomic
-        *  with regard to checking the flag as long as waitqueue is
-        *  part of the to be released structure)
-        */
-               wake_up(&req->completion_wq);
+               complete(&req->completion);
 }
 
 /**
@@ -733,7 +721,7 @@ static struct zfcp_fsf_req *zfcp_fsf_req_create(struct zfcp_adapter *adapter,
 
        INIT_LIST_HEAD(&req->list);
        init_timer(&req->timer);
-       init_waitqueue_head(&req->completion_wq);
+       init_completion(&req->completion);
 
        req->adapter = adapter;
        req->fsf_command = fsf_cmd;
@@ -1309,8 +1297,7 @@ int zfcp_fsf_exchange_config_data_sync(struct zfcp_adapter *adapter,
        retval = zfcp_fsf_req_send(req);
        spin_unlock_bh(&adapter->req_q_lock);
        if (!retval)
-               wait_event(req->completion_wq,
-                          req->status & ZFCP_STATUS_FSFREQ_COMPLETED);
+               wait_for_completion(&req->completion);
 
        zfcp_fsf_req_free(req);
        return retval;
@@ -1405,8 +1392,8 @@ int zfcp_fsf_exchange_port_data_sync(struct zfcp_adapter *adapter,
        spin_unlock_bh(&adapter->req_q_lock);
 
        if (!retval)
-               wait_event(req->completion_wq,
-                          req->status & ZFCP_STATUS_FSFREQ_COMPLETED);
+               wait_for_completion(&req->completion);
+
        zfcp_fsf_req_free(req);
 
        return retval;
@@ -2572,8 +2559,7 @@ out:
        spin_unlock_bh(&adapter->req_q_lock);
 
        if (!retval) {
-               wait_event(req->completion_wq,
-                          req->status & ZFCP_STATUS_FSFREQ_COMPLETED);
+               wait_for_completion(&req->completion);
                return req;
        }
        return ERR_PTR(retval);

diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c
index 0bd80a9..0de0591 100644 (file)
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -206,8 +206,7 @@ static int zfcp_scsi_eh_abort_handler(struct scsi_cmnd *scpnt)
        if (!abrt_req)
                return FAILED;
 
-       wait_event(abrt_req->completion_wq,
-                  abrt_req->status & ZFCP_STATUS_FSFREQ_COMPLETED);
+       wait_for_completion(&abrt_req->completion);
 
        if (abrt_req->status & ZFCP_STATUS_FSFREQ_ABORTSUCCEEDED)
                dbf_tag = "okay";
@@ -246,8 +245,7 @@ static int zfcp_task_mgmt_function(struct scsi_cmnd *scpnt, u8 tm_flags)
        if (!fsf_req)
                return FAILED;
 
-       wait_event(fsf_req->completion_wq,
-                  fsf_req->status & ZFCP_STATUS_FSFREQ_COMPLETED);
+       wait_for_completion(&fsf_req->completion);
 
        if (fsf_req->status & ZFCP_STATUS_FSFREQ_TMFUNCFAILED) {
                zfcp_scsi_dbf_event_devreset("fail", tm_flags, unit, scpnt);