[SCSI] zfcp: Change spin_lock_bh to spin_lock_irq to fix lockdep warning

With the change to use the data on the SCSI device, iterating through
all LUNs/scsi_devices takes the SCSI host_lock. This triggers warnings
from the lock dependency checker:

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
2.6.34.1 #97
---------------------------------------------------------
chchp/3224 just changed the state of lock:
 (&(shost->host_lock)->rlock){-.-...}, at: [<00000000003a73f4>] __scsi_iterate_devices+0x38/0xbc
but this lock took another, HARDIRQ-unsafe lock in the past:
 (&(&qdio->req_q_lock)->rlock){+.-...}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this: [   24.972394] 2 locks held by chchp/3224:
 #0:  (&(sch->lock)->rlock){-.-...}, at: [<0000000000401efa>] do_IRQ+0xb2/0x1e4
 #1:  (&adapter->port_list_lock){.-....}, at: [<0000000000490302>] zfcp_erp_modify_adapter_status+0x9e/0x16c
[...]

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
2.6.34.1 #98
---------------------------------------------------------
chchp/3235 just changed the state of lock:
 (&(shost->host_lock)->rlock){-.-...}, at: [<00000000003a73f4>] __scsi_iterate_devices+0x38/0xbc
but this lock took another, HARDIRQ-unsafe lock in the past:
 (&(&qdio->stat_lock)->rlock){+.-...}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
2 locks held by chchp/3235:
 #0:  (&(sch->lock)->rlock){-.-...}, at: [<0000000000401efa>] do_IRQ+0xb2/0x1e4
 #1:  (&adapter->port_list_lock){.-.-..}, at: [<00000000004902f6>] zfcp_erp_modify_adapter_status+0x9e/0x16c
[...]

To stop this warning, change the request queue lock to disable irqs,
not only softirq. The changes are required only outside of the
critical "send fcp command" path.

Reviewed-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>

1 files changed, 10 insertions, 8 deletions

diff --git a/drivers/s390/scsi/zfcp_qdio.c b/drivers/s390/scsi/zfcp_qdio.c
index b2635759721c..60e6e5714eb9 100644
--- a/drivers/s390/scsi/zfcp_qdio.c
+++ b/drivers/s390/scsi/zfcp_qdio.c
@@ -60,13 +60,11 @@ static inline void zfcp_qdio_account(struct zfcp_qdio *qdio)
         unsigned long long now, span;
         int used;
 
-        spin_lock(&qdio->stat_lock);
         now = get_clock_monotonic();
         span = (now - qdio->req_q_time) >> 12;
         used = QDIO_MAX_BUFFERS_PER_Q - atomic_read(&qdio->req_q_free);
         qdio->req_q_util += used * span;
         qdio->req_q_time = now;
-        spin_unlock(&qdio->stat_lock);
 }
 
 static void zfcp_qdio_int_req(struct ccw_device *cdev, unsigned int qdio_err,
@@ -84,7 +82,9 @@ static void zfcp_qdio_int_req(struct ccw_device *cdev, unsigned int qdio_err,
         /* cleanup all SBALs being program-owned now */
         zfcp_qdio_zero_sbals(qdio->req_q, idx, count);
 
+        spin_lock_irq(&qdio->stat_lock);
         zfcp_qdio_account(qdio);
+        spin_unlock_irq(&qdio->stat_lock);
         atomic_add(count, &qdio->req_q_free);
         wake_up(&qdio->req_q_wq);
 }
@@ -201,11 +201,11 @@ int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req,
 
 static int zfcp_qdio_sbal_check(struct zfcp_qdio *qdio)
 {
-        spin_lock_bh(&qdio->req_q_lock);
+        spin_lock_irq(&qdio->req_q_lock);
         if (atomic_read(&qdio->req_q_free) ||
             !(atomic_read(&qdio->adapter->status) & ZFCP_STATUS_ADAPTER_QDIOUP))
                 return 1;
-        spin_unlock_bh(&qdio->req_q_lock);
+        spin_unlock_irq(&qdio->req_q_lock);
         return 0;
 }
 
@@ -223,7 +223,7 @@ int zfcp_qdio_sbal_get(struct zfcp_qdio *qdio)
 {
         long ret;
 
-        spin_unlock_bh(&qdio->req_q_lock);
+        spin_unlock_irq(&qdio->req_q_lock);
         ret = wait_event_interruptible_timeout(qdio->req_q_wq,
                                zfcp_qdio_sbal_check(qdio), 5 * HZ);
 
@@ -239,7 +239,7 @@ int zfcp_qdio_sbal_get(struct zfcp_qdio *qdio)
                 zfcp_erp_adapter_reopen(qdio->adapter, 0, "qdsbg_1", NULL);
         }
 
-        spin_lock_bh(&qdio->req_q_lock);
+        spin_lock_irq(&qdio->req_q_lock);
         return -EIO;
 }
 
@@ -254,7 +254,9 @@ int zfcp_qdio_send(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
         int retval;
         u8 sbal_number = q_req->sbal_number;
 
+        spin_lock(&qdio->stat_lock);
         zfcp_qdio_account(qdio);
+        spin_unlock(&qdio->stat_lock);
 
         retval = do_QDIO(qdio->adapter->ccw_device, QDIO_FLAG_SYNC_OUTPUT, 0,
                          q_req->sbal_first, sbal_number);
@@ -328,9 +330,9 @@ void zfcp_qdio_close(struct zfcp_qdio *qdio)
                 return;
 
         /* clear QDIOUP flag, thus do_QDIO is not called during qdio_shutdown */
-        spin_lock_bh(&qdio->req_q_lock);
+        spin_lock_irq(&qdio->req_q_lock);
         atomic_clear_mask(ZFCP_STATUS_ADAPTER_QDIOUP, &adapter->status);
-        spin_unlock_bh(&qdio->req_q_lock);
+        spin_unlock_irq(&qdio->req_q_lock);
 
         wake_up(&qdio->req_q_wq);