[S390] chsc: use the global page to determine the chp desriptor

chsc_determine_channel_path_desc is called by a wrapper
who allocates a response struct. The response data
is then memcpy'ed to this response struct by
chsc_determine_channel_path_desc.

Change chsc_determine_base_channel_path_desc to use the
global chsc_page and deliver it to the function doing
the actual chsc call. The channel path desriptor is
then directly read from the response data.

As a result we get rid of the additional allocation
for the response struct.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 15 insertions, 39 deletions

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index d12c152cb691..27aca3906a53 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -639,36 +639,18 @@ chsc_secm(struct channel_subsystem *css, int enable)
 }
 
 int chsc_determine_channel_path_desc(struct chp_id chpid, int fmt, int rfmt,
-                                     int c, int m,
-                                     struct chsc_response_struct *resp)
+                                     int c, int m, void *page)
 {
+        struct chsc_scpd *scpd_area;
         int ccode, ret;
 
-        struct {
-                struct chsc_header request;
-                u32 : 2;
-                u32 m : 1;
-                u32 c : 1;
-                u32 fmt : 4;
-                u32 cssid : 8;
-                u32 : 4;
-                u32 rfmt : 4;
-                u32 first_chpid : 8;
-                u32 : 24;
-                u32 last_chpid : 8;
-                u32 zeroes1;
-                struct chsc_header response;
-                u8 data[PAGE_SIZE - 20];
-        } __attribute__ ((packed)) *scpd_area;
-
         if ((rfmt == 1) && !css_general_characteristics.fcs)
                 return -EINVAL;
         if ((rfmt == 2) && !css_general_characteristics.cib)
                 return -EINVAL;
 
-        spin_lock_irq(&chsc_page_lock);
-        memset(chsc_page, 0, PAGE_SIZE);
-        scpd_area = chsc_page;
+        memset(page, 0, PAGE_SIZE);
+        scpd_area = page;
         scpd_area->request.length = 0x0010;
         scpd_area->request.code = 0x0002;
         scpd_area->cssid = chpid.cssid;
@@ -680,20 +662,13 @@ int chsc_determine_channel_path_desc(struct chp_id chpid, int fmt, int rfmt,
         scpd_area->rfmt = rfmt;
 
         ccode = chsc(scpd_area);
-        if (ccode > 0) {
-                ret = (ccode == 3) ? -ENODEV : -EBUSY;
-                goto out;
-        }
+        if (ccode > 0)
+                return (ccode == 3) ? -ENODEV : -EBUSY;
 
         ret = chsc_error_from_response(scpd_area->response.code);
-        if (ret == 0)
-                /* Success. */
-                memcpy(resp, &scpd_area->response, scpd_area->response.length);
-        else
+        if (ret)
                 CIO_CRW_EVENT(2, "chsc: scpd failed (rc=%04x)\n",
                               scpd_area->response.code);
-out:
-        spin_unlock_irq(&chsc_page_lock);
         return ret;
 }
 EXPORT_SYMBOL_GPL(chsc_determine_channel_path_desc);
@@ -702,17 +677,18 @@ int chsc_determine_base_channel_path_desc(struct chp_id chpid,
                                           struct channel_path_desc *desc)
 {
         struct chsc_response_struct *chsc_resp;
+        struct chsc_scpd *scpd_area;
         int ret;
 
-        chsc_resp = kzalloc(sizeof(*chsc_resp), GFP_KERNEL);
-        if (!chsc_resp)
-                return -ENOMEM;
-        ret = chsc_determine_channel_path_desc(chpid, 0, 0, 0, 0, chsc_resp);
+        spin_lock_irq(&chsc_page_lock);
+        scpd_area = chsc_page;
+        ret = chsc_determine_channel_path_desc(chpid, 0, 0, 0, 0, scpd_area);
         if (ret)
-                goto out_free;
+                goto out;
+        chsc_resp = (void *)&scpd_area->response;
         memcpy(desc, &chsc_resp->data, sizeof(*desc));
-out_free:
-        kfree(chsc_resp);
+out:
+        spin_unlock_irq(&chsc_page_lock);
         return ret;
 }