[SCSI] zfcp: Use kthread API for zfcp erp thread

Switch the creation of the zfcp erp thread from the deprecated
kernel_thread API to the kthread API. This allows also the removal of
some flags in zfcp since the kthread API handles thread creation and
shutdown internally. To allow the usage of the kthread_stop function,
replace the erp ready semaphore with a waitqueue for waiting until erp
actions arrive on the ready queue.

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>

3 files changed, 27 insertions, 45 deletions

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index ed9a8a1517c6..e8f39f02bc3b 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -529,7 +529,7 @@ int zfcp_adapter_enqueue(struct ccw_device *ccw_device)
                 goto generic_services_failed;
 
         init_waitqueue_head(&adapter->remove_wq);
-        init_waitqueue_head(&adapter->erp_thread_wqh);
+        init_waitqueue_head(&adapter->erp_ready_wq);
         init_waitqueue_head(&adapter->erp_done_wqh);
 
         INIT_LIST_HEAD(&adapter->port_list_head);
@@ -541,8 +541,6 @@ int zfcp_adapter_enqueue(struct ccw_device *ccw_device)
         rwlock_init(&adapter->erp_lock);
         rwlock_init(&adapter->abort_lock);
 
-        sema_init(&adapter->erp_ready_sem, 0);
-
         INIT_WORK(&adapter->stat_work, _zfcp_status_read_scheduler);
         INIT_WORK(&adapter->scan_work, _zfcp_fc_scan_ports_later);
 
diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index 9a8ff0553421..ce65d88e280c 100644
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -222,8 +222,6 @@ struct zfcp_ls_adisc {
 #define ZFCP_STATUS_ADAPTER_QDIOUP              0x00000002
 #define ZFCP_STATUS_ADAPTER_XCONFIG_OK          0x00000008
 #define ZFCP_STATUS_ADAPTER_HOST_CON_INIT       0x00000010
-#define ZFCP_STATUS_ADAPTER_ERP_THREAD_UP       0x00000020
-#define ZFCP_STATUS_ADAPTER_ERP_THREAD_KILL     0x00000080
 #define ZFCP_STATUS_ADAPTER_ERP_PENDING         0x00000100
 #define ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED      0x00000200
 
@@ -481,10 +479,9 @@ struct zfcp_adapter {
         atomic_t                status;            /* status of this adapter */
         struct list_head        erp_ready_head;    /* error recovery for this
                                                       adapter/devices */
+        wait_queue_head_t       erp_ready_wq;
         struct list_head        erp_running_head;
         rwlock_t                erp_lock;
-        struct semaphore        erp_ready_sem;
-        wait_queue_head_t       erp_thread_wqh;
         wait_queue_head_t       erp_done_wqh;
         struct zfcp_erp_action  erp_action;        /* pending error recovery */
         atomic_t                erp_counter;
@@ -492,6 +489,7 @@ struct zfcp_adapter {
                                                       actions */
         u32                     erp_low_mem_count; /* nr of erp actions waiting
                                                       for memory */
+        struct task_struct      *erp_thread;
         struct zfcp_wka_ports   *gs;               /* generic services */
         struct zfcp_dbf         *dbf;              /* debug traces */
         struct zfcp_adapter_mempool     pool;      /* Adapter memory pools */
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 373567eda8f6..577e15708598 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -9,6 +9,7 @@
 #define KMSG_COMPONENT "zfcp"
 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 
+#include <linux/kthread.h>
 #include "zfcp_ext.h"
 
 #define ZFCP_MAX_ERPS                   3
@@ -75,7 +76,7 @@ static void zfcp_erp_action_ready(struct zfcp_erp_action *act)
 
         list_move(&act->list, &act->adapter->erp_ready_head);
         zfcp_dbf_rec_action("erardy1", act);
-        up(&adapter->erp_ready_sem);
+        wake_up(&adapter->erp_ready_wq);
         zfcp_dbf_rec_thread("erardy2", adapter->dbf);
 }
 
@@ -212,8 +213,7 @@ static int zfcp_erp_action_enqueue(int want, struct zfcp_adapter *adapter,
         int retval = 1, need;
         struct zfcp_erp_action *act = NULL;
 
-        if (!(atomic_read(&adapter->status) &
-              ZFCP_STATUS_ADAPTER_ERP_THREAD_UP))
+        if (!adapter->erp_thread)
                 return -EIO;
 
         need = zfcp_erp_required_act(want, adapter, port, unit);
@@ -226,7 +226,7 @@ static int zfcp_erp_action_enqueue(int want, struct zfcp_adapter *adapter,
                 goto out;
         ++adapter->erp_total_count;
         list_add_tail(&act->list, &adapter->erp_ready_head);
-        up(&adapter->erp_ready_sem);
+        wake_up(&adapter->erp_ready_wq);
         zfcp_dbf_rec_thread("eracte1", adapter->dbf);
         retval = 0;
  out:
@@ -641,7 +641,8 @@ static int zfcp_erp_adapter_strat_fsf_xconf(struct zfcp_erp_action *erp_action)
                 }
 
                 zfcp_dbf_rec_thread_lock("erasfx1", adapter->dbf);
-                down(&adapter->erp_ready_sem);
+                wait_event(adapter->erp_ready_wq,
+                           !list_empty(&adapter->erp_ready_head));
                 zfcp_dbf_rec_thread_lock("erasfx2", adapter->dbf);
                 if (erp_action->status & ZFCP_STATUS_ERP_TIMEDOUT)
                         break;
@@ -682,7 +683,8 @@ static int zfcp_erp_adapter_strategy_open_fsf_xport(struct zfcp_erp_action *act)
                 return ZFCP_ERP_FAILED;
 
         zfcp_dbf_rec_thread_lock("erasox1", adapter->dbf);
-        down(&adapter->erp_ready_sem);
+        wait_event(adapter->erp_ready_wq,
+                   !list_empty(&adapter->erp_ready_head));
         zfcp_dbf_rec_thread_lock("erasox2", adapter->dbf);
         if (act->status & ZFCP_STATUS_ERP_TIMEDOUT)
                 return ZFCP_ERP_FAILED;
@@ -1285,21 +1287,17 @@ static int zfcp_erp_thread(void *data)
         struct list_head *next;
         struct zfcp_erp_action *act;
         unsigned long flags;
-        int ignore;
-
-        daemonize("zfcperp%s", dev_name(&adapter->ccw_device->dev));
-        /* Block all signals */
-        siginitsetinv(&current->blocked, 0);
-        atomic_set_mask(ZFCP_STATUS_ADAPTER_ERP_THREAD_UP, &adapter->status);
-        wake_up(&adapter->erp_thread_wqh);
-
-        while (!(atomic_read(&adapter->status) &
-                 ZFCP_STATUS_ADAPTER_ERP_THREAD_KILL)) {
 
+        for (;;) {
                 zfcp_dbf_rec_thread_lock("erthrd1", adapter->dbf);
-                ignore = down_interruptible(&adapter->erp_ready_sem);
+                wait_event_interruptible(adapter->erp_ready_wq,
+                           !list_empty(&adapter->erp_ready_head) ||
+                           kthread_should_stop());
                 zfcp_dbf_rec_thread_lock("erthrd2", adapter->dbf);
 
+                if (kthread_should_stop())
+                        break;
+
                 write_lock_irqsave(&adapter->erp_lock, flags);
                 next = adapter->erp_ready_head.next;
                 write_unlock_irqrestore(&adapter->erp_lock, flags);
@@ -1313,9 +1311,6 @@ static int zfcp_erp_thread(void *data)
                 }
         }
 
-        atomic_clear_mask(ZFCP_STATUS_ADAPTER_ERP_THREAD_UP, &adapter->status);
-        wake_up(&adapter->erp_thread_wqh);
-
         return 0;
 }
 
@@ -1327,18 +1322,17 @@ static int zfcp_erp_thread(void *data)
  */
 int zfcp_erp_thread_setup(struct zfcp_adapter *adapter)
 {
-        int retval;
+        struct task_struct *thread;
 
-        atomic_clear_mask(ZFCP_STATUS_ADAPTER_ERP_THREAD_UP, &adapter->status);
-        retval = kernel_thread(zfcp_erp_thread, adapter, SIGCHLD);
-        if (retval < 0) {
+        thread = kthread_run(zfcp_erp_thread, adapter, "zfcperp%s",
+                             dev_name(&adapter->ccw_device->dev));
+        if (IS_ERR(thread)) {
                 dev_err(&adapter->ccw_device->dev,
                         "Creating an ERP thread for the FCP device failed.\n");
-                return retval;
+                return PTR_ERR(thread);
         }
-        wait_event(adapter->erp_thread_wqh,
-                   atomic_read(&adapter->status) &
-                        ZFCP_STATUS_ADAPTER_ERP_THREAD_UP);
+
+        adapter->erp_thread = thread;
         return 0;
 }
 
@@ -1353,16 +1347,8 @@ int zfcp_erp_thread_setup(struct zfcp_adapter *adapter)
  */
 void zfcp_erp_thread_kill(struct zfcp_adapter *adapter)
 {
-        atomic_set_mask(ZFCP_STATUS_ADAPTER_ERP_THREAD_KILL, &adapter->status);
-        up(&adapter->erp_ready_sem);
-        zfcp_dbf_rec_thread_lock("erthrk1", adapter->dbf);
-
-        wait_event(adapter->erp_thread_wqh,
-                   !(atomic_read(&adapter->status) &
-                                ZFCP_STATUS_ADAPTER_ERP_THREAD_UP));
-
-        atomic_clear_mask(ZFCP_STATUS_ADAPTER_ERP_THREAD_KILL,
-                          &adapter->status);
+        kthread_stop(adapter->erp_thread);
+        adapter->erp_thread = NULL;
 }
 
 /**