[S390] cio async subchannel reprobe.

Changes in the DASD driver require an asynchronous implementation of the
subchannel reprobe loop. This loop was so far only used by the blacklisting
mechanism but is now available to all CCW device drivers.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 74ea8aac4b7d..1d3be80797f8 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -19,9 +19,11 @@
 #include "cio_debug.h"
 #include "ioasm.h"
 #include "chsc.h"
+#include "device.h"
 
 int need_rescan = 0;
 int css_init_done = 0;
+static int need_reprobe = 0;
 static int max_ssid = 0;
 
 struct channel_subsystem *css[__MAX_CSSID + 1];
@@ -339,6 +341,67 @@ typedef void (*workfunc)(void *);
 DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
 struct workqueue_struct *slow_path_wq;
 
+/* Reprobe subchannel if unregistered. */
+static int reprobe_subchannel(struct subchannel_id schid, void *data)
+{
+        struct subchannel *sch;
+        int ret;
+
+        CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
+                  schid.ssid, schid.sch_no);
+        if (need_reprobe)
+                return -EAGAIN;
+
+        sch = get_subchannel_by_schid(schid);
+        if (sch) {
+                /* Already known. */
+                put_device(&sch->dev);
+                return 0;
+        }
+
+        ret = css_probe_device(schid);
+        switch (ret) {
+        case 0:
+                break;
+        case -ENXIO:
+        case -ENOMEM:
+                /* These should abort looping */
+                break;
+        default:
+                ret = 0;
+        }
+
+        return ret;
+}
+
+/* Work function used to reprobe all unregistered subchannels. */
+static void reprobe_all(void *data)
+{
+        int ret;
+
+        CIO_MSG_EVENT(2, "reprobe start\n");
+
+        need_reprobe = 0;
+        /* Make sure initial subchannel scan is done. */
+        wait_event(ccw_device_init_wq,
+                   atomic_read(&ccw_device_init_count) == 0);
+        ret = for_each_subchannel(reprobe_subchannel, NULL);
+
+        CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
+                      need_reprobe);
+}
+
+DECLARE_WORK(css_reprobe_work, reprobe_all, NULL);
+
+/* Schedule reprobing of all unregistered subchannels. */
+void css_schedule_reprobe(void)
+{
+        need_reprobe = 1;
+        queue_work(ccw_device_work, &css_reprobe_work);
+}
+
+EXPORT_SYMBOL_GPL(css_schedule_reprobe);
+
 /*
  * Rescan for new devices. FIXME: This is slow.
  * This function is called when we have lost CRWs due to overflows and we have