s390/css: reduce stsch calls

Both css_evaluate_new_subchannel and cio_validate_subchannel used
stsch and css_sch_is_valid to check for a valid device.

Reduce stsch calls during subchannel evaluation by re-using schib
data. Also the type/devno valid information is only checked once.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 4b8f29f..de744ca 100644 (file)
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -526,64 +526,6 @@ int cio_disable_subchannel(struct subchannel *sch)
 }
 EXPORT_SYMBOL_GPL(cio_disable_subchannel);
 
-/**
- * cio_validate_subchannel - basic validation of subchannel
- * @schid: subchannel id
- * @schib: subchannel information block to be filled out
- *
- * Check if subchannel is valid and should be used.
- * Return codes:
- *   0 on success
- *   -ENXIO for non-defined subchannels
- *   -ENODEV for invalid subchannels or blacklisted devices
- *   -EIO for subchannels in an invalid subchannel set
- */
-int cio_validate_subchannel(struct subchannel_id schid, struct schib *schib)
-{
-       char dbf_txt[15];
-       int ccode;
-       int err;
-
-       sprintf(dbf_txt, "valsch%x", schid.sch_no);
-       CIO_TRACE_EVENT(4, dbf_txt);
-
-       /*
-        * The first subchannel that is not-operational (ccode==3)
-        * indicates that there aren't any more devices available.
-        * If stsch gets an exception, it means the current subchannel set
-        * is not valid.
-        */
-       ccode = stsch(schid, schib);
-       if (ccode) {
-               err = (ccode == 3) ? -ENXIO : ccode;
-               goto out;
-       }
-
-       switch (schib->pmcw.st) {
-       case SUBCHANNEL_TYPE_IO:
-       case SUBCHANNEL_TYPE_MSG:
-               if (!css_sch_is_valid(schib))
-                       err = -ENODEV;
-               else if (is_blacklisted(schid.ssid, schib->pmcw.dev)) {
-                       CIO_MSG_EVENT(6, "Blacklisted device detected "
-                                     "at devno %04X, subchannel set %x\n",
-                                     schib->pmcw.dev, schid.ssid);
-                       err = -ENODEV;
-               } else
-                       err = 0;
-               break;
-       default:
-               err = 0;
-       }
-       if (err)
-               goto out;
-
-       CIO_MSG_EVENT(4, "Subchannel 0.%x.%04x reports subchannel type %04X\n",
-                     schid.ssid, schid.sch_no, schib->pmcw.st);
-out:
-       return err;
-}
-
 /*
  * do_cio_interrupt() handles all normal I/O device IRQ's
  */
@@ -707,6 +649,7 @@ struct subchannel *cio_probe_console(void)
 {
        struct subchannel_id schid;
        struct subchannel *sch;
+       struct schib schib;
        int sch_no, ret;
 
        sch_no = cio_get_console_sch_no();
@@ -716,7 +659,11 @@ struct subchannel *cio_probe_console(void)
        }
        init_subchannel_id(&schid);
        schid.sch_no = sch_no;
-       sch = css_alloc_subchannel(schid);
+       ret = stsch(schid, &schib);
+       if (ret)
+               return ERR_PTR(-ENODEV);
+
+       sch = css_alloc_subchannel(schid, &schib);
        if (IS_ERR(sch))
                return sch;
 

diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 234aa06..9811fd8 100644 (file)
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -119,7 +119,6 @@ DECLARE_PER_CPU(struct irb, cio_irb);
 
 #define to_subchannel(n) container_of(n, struct subchannel, dev)
 
-extern int cio_validate_subchannel(struct subchannel_id, struct schib *);
 extern int cio_enable_subchannel(struct subchannel *, u32);
 extern int cio_disable_subchannel (struct subchannel *);
 extern int cio_cancel (struct subchannel *);

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index e4d6537..aea5029 100644 (file)
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -25,6 +25,7 @@
 
 #include "css.h"
 #include "cio.h"
+#include "blacklist.h"
 #include "cio_debug.h"
 #include "ioasm.h"
 #include "chsc.h"
@@ -168,13 +169,43 @@ static void css_subchannel_release(struct device *dev)
        kfree(sch);
 }
 
-struct subchannel *css_alloc_subchannel(struct subchannel_id schid)
+static int css_validate_subchannel(struct subchannel_id schid,
+                                  struct schib *schib)
+{
+       int err;
+
+       switch (schib->pmcw.st) {
+       case SUBCHANNEL_TYPE_IO:
+       case SUBCHANNEL_TYPE_MSG:
+               if (!css_sch_is_valid(schib))
+                       err = -ENODEV;
+               else if (is_blacklisted(schid.ssid, schib->pmcw.dev)) {
+                       CIO_MSG_EVENT(6, "Blacklisted device detected "
+                                     "at devno %04X, subchannel set %x\n",
+                                     schib->pmcw.dev, schid.ssid);
+                       err = -ENODEV;
+               } else
+                       err = 0;
+               break;
+       default:
+               err = 0;
+       }
+       if (err)
+               goto out;
+
+       CIO_MSG_EVENT(4, "Subchannel 0.%x.%04x reports subchannel type %04X\n",
+                     schid.ssid, schid.sch_no, schib->pmcw.st);
+out:
+       return err;
+}
+
+struct subchannel *css_alloc_subchannel(struct subchannel_id schid,
+                                       struct schib *schib)
 {
        struct subchannel *sch;
-       struct schib schib;
        int ret;
 
-       ret = cio_validate_subchannel(schid, &schib);
+       ret = css_validate_subchannel(schid, schib);
        if (ret < 0)
                return ERR_PTR(ret);
 
@@ -183,8 +214,8 @@ struct subchannel *css_alloc_subchannel(struct subchannel_id schid)
                return ERR_PTR(-ENOMEM);
 
        sch->schid = schid;
-       sch->schib = schib;
-       sch->st = schib.pmcw.st;
+       sch->schib = *schib;
+       sch->st = schib->pmcw.st;
 
        ret = css_sch_create_locks(sch);
        if (ret)
@@ -386,12 +417,12 @@ int css_register_subchannel(struct subchannel *sch)
        return ret;
 }
 
-static int css_probe_device(struct subchannel_id schid)
+static int css_probe_device(struct subchannel_id schid, struct schib *schib)
 {
        struct subchannel *sch;
        int ret;
 
-       sch = css_alloc_subchannel(schid);
+       sch = css_alloc_subchannel(schid, schib);
        if (IS_ERR(sch))
                return PTR_ERR(sch);
 
@@ -440,23 +471,23 @@ EXPORT_SYMBOL_GPL(css_sch_is_valid);
 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 {
        struct schib schib;
+       int ccode;
 
        if (!slow) {
                /* Will be done on the slow path. */
                return -EAGAIN;
        }
-       if (stsch(schid, &schib)) {
-               /* Subchannel is not provided. */
-               return -ENXIO;
-       }
-       if (!css_sch_is_valid(&schib)) {
-               /* Unusable - ignore. */
-               return 0;
-       }
-       CIO_MSG_EVENT(4, "event: sch 0.%x.%04x, new\n", schid.ssid,
-                     schid.sch_no);
+       /*
+        * The first subchannel that is not-operational (ccode==3)
+        * indicates that there aren't any more devices available.
+        * If stsch gets an exception, it means the current subchannel set
+        * is not valid.
+        */
+       ccode = stsch(schid, &schib);
+       if (ccode)
+               return (ccode == 3) ? -ENXIO : ccode;
 
-       return css_probe_device(schid);
+       return css_probe_device(schid, &schib);
 }
 
 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)

diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h
index 30357cb..8d83290 100644 (file)
--- a/drivers/s390/cio/css.h
+++ b/drivers/s390/cio/css.h
@@ -103,7 +103,8 @@ extern void css_driver_unregister(struct css_driver *);
 
 extern void css_sch_device_unregister(struct subchannel *);
 extern int css_register_subchannel(struct subchannel *);
-extern struct subchannel *css_alloc_subchannel(struct subchannel_id);
+extern struct subchannel *css_alloc_subchannel(struct subchannel_id,
+                                              struct schib *schib);
 extern struct subchannel *get_subchannel_by_schid(struct subchannel_id);
 extern int css_init_done;
 extern int max_ssid;