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authorSwen Schillig <swen@vnet.ibm.com>2009-04-17 15:08:06 +0200
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2009-04-27 10:07:28 -0500
commit94ab4b38b2ab35a8ca955f4821c970a0ed7ec9ec (patch)
tree78b0d65b56e48a4753f39d277a13030f6d8b77d9 /drivers
parent828bc1212a685918bbdb5866504b63eea2c241f5 (diff)
[SCSI] zfcp: avoid false ERP complete due to sema race
The ERP thread is performing a task before it is executing the corresponding down on the semaphore. The response handler of the just started exchange config should wait for the completion by performing a down on this semaphore. Since this semaphore is still positive from the ERP enqueue the handler won't wait and therefore the exchange config will always fail leaving the adapter in error. The problem can be solved by performing the down on the semaphore before starting an ERP task. This is the logically correct order. Only walk the ERP loop if there is a task to perform. 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@HansenPartnership.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/s390/scsi/zfcp_erp.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index b73e37027eb..fdc9b4352a6 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -1311,6 +1311,11 @@ static int zfcp_erp_thread(void *data)
while (!(atomic_read(&adapter->status) &
ZFCP_STATUS_ADAPTER_ERP_THREAD_KILL)) {
+
+ zfcp_rec_dbf_event_thread_lock("erthrd1", adapter);
+ ignore = down_interruptible(&adapter->erp_ready_sem);
+ zfcp_rec_dbf_event_thread_lock("erthrd2", adapter);
+
write_lock_irqsave(&adapter->erp_lock, flags);
next = adapter->erp_ready_head.next;
write_unlock_irqrestore(&adapter->erp_lock, flags);
@@ -1322,10 +1327,6 @@ static int zfcp_erp_thread(void *data)
if (zfcp_erp_strategy(act) != ZFCP_ERP_DISMISSED)
zfcp_erp_wakeup(adapter);
}
-
- zfcp_rec_dbf_event_thread_lock("erthrd1", adapter);
- ignore = down_interruptible(&adapter->erp_ready_sem);
- zfcp_rec_dbf_event_thread_lock("erthrd2", adapter);
}
atomic_clear_mask(ZFCP_STATUS_ADAPTER_ERP_THREAD_UP, &adapter->status);