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[SCSI] zfcp: Locking for req_no and req_seq_no 

There is a possible race condition while generating the unique
request ids and sequence numbers. Both might be read at the
same time and have the same value. Fix this by serializing the
access through the queue lock of the adapter: First call
zfcp_fsf_req_sbal_get that acquires the lock, then read and
increment the unique ids.

Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Christof Schmitt 2007-05-08 11:15:48 +02:00 committed by James Bottomley
parent 1d589edf9e
commit 801e0ced18
1 changed files with 8 additions and 9 deletions
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17
drivers/s390/scsi/zfcp_fsf.c
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@ -4645,23 +4645,22 @@ zfcp_fsf_req_create(struct zfcp_adapter *adapter, u32 fsf_cmd, int req_flags,
fsf_req->adapter = adapter;
fsf_req->fsf_command = fsf_cmd;
INIT_LIST_HEAD(&fsf_req->list);
/* this is serialized (we are holding req_queue-lock of adapter */
if (adapter->req_no == 0)
adapter->req_no++;
fsf_req->req_id = adapter->req_no++;
init_timer(&fsf_req->timer);
zfcp_fsf_req_qtcb_init(fsf_req);
/* initialize waitqueue which may be used to wait on
this request completion */
init_waitqueue_head(&fsf_req->completion_wq);
ret = zfcp_fsf_req_sbal_get(adapter, req_flags, lock_flags);
if(ret < 0) {
if (ret < 0)
goto failed_sbals;
}
/* this is serialized (we are holding req_queue-lock of adapter) */
if (adapter->req_no == 0)
adapter->req_no++;
fsf_req->req_id = adapter->req_no++;
zfcp_fsf_req_qtcb_init(fsf_req);
/*
* We hold queue_lock here. Check if QDIOUP is set and let request fail