[S390] cio: allow enable_facility from outside init functions

Prepare chsc_enable_facility to be used from outside init functions.
Use static memory for the chsc call and protect its access by a
spinlock (although there is no concurrent usage).

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

2 files changed, 17 insertions, 23 deletions

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index 4038f5b4f144..ce7cb87479fe 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -29,6 +29,7 @@
 #include "chsc.h"
 
 static void *sei_page;
+static DEFINE_SPINLOCK(sda_lock);
 
 /**
  * chsc_error_from_response() - convert a chsc response to an error
@@ -832,11 +833,10 @@ void __init chsc_free_sei_area(void)
         kfree(sei_page);
 }
 
-int __init
-chsc_enable_facility(int operation_code)
+int chsc_enable_facility(int operation_code)
 {
         int ret;
-        struct {
+        static struct {
                 struct chsc_header request;
                 u8 reserved1:4;
                 u8 format:4;
@@ -849,33 +849,32 @@ chsc_enable_facility(int operation_code)
                 u32 reserved5:4;
                 u32 format2:4;
                 u32 reserved6:24;
-        } __attribute__ ((packed)) *sda_area;
+        } __attribute__ ((packed, aligned(4096))) sda_area;
 
-        sda_area = (void *)get_zeroed_page(GFP_KERNEL|GFP_DMA);
-        if (!sda_area)
-                return -ENOMEM;
-        sda_area->request.length = 0x0400;
-        sda_area->request.code = 0x0031;
-        sda_area->operation_code = operation_code;
+        spin_lock(&sda_lock);
+        memset(&sda_area, 0, sizeof(sda_area));
+        sda_area.request.length = 0x0400;
+        sda_area.request.code = 0x0031;
+        sda_area.operation_code = operation_code;
 
-        ret = chsc(sda_area);
+        ret = chsc(&sda_area);
         if (ret > 0) {
                 ret = (ret == 3) ? -ENODEV : -EBUSY;
                 goto out;
         }
 
-        switch (sda_area->response.code) {
+        switch (sda_area.response.code) {
         case 0x0101:
                 ret = -EOPNOTSUPP;
                 break;
         default:
-                ret = chsc_error_from_response(sda_area->response.code);
+                ret = chsc_error_from_response(sda_area.response.code);
         }
         if (ret != 0)
                 CIO_CRW_EVENT(2, "chsc: sda (oc=%x) failed (rc=%04x)\n",
-                              operation_code, sda_area->response.code);
+                              operation_code, sda_area.response.code);
  out:
-        free_page((unsigned long)sda_area);
+        spin_unlock(&sda_lock);
         return ret;
 }
 
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 2769da54f2b9..19635d47dede 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -870,15 +870,10 @@ static int __init css_bus_init(void)
 
         /* Try to enable MSS. */
         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
-        switch (ret) {
-        case 0: /* Success. */
-                max_ssid = __MAX_SSID;
-                break;
-        case -ENOMEM:
-                goto out;
-        default:
+        if (ret)
                 max_ssid = 0;
-        }
+        else /* Success. */
+                max_ssid = __MAX_SSID;
 
         ret = slow_subchannel_init();
         if (ret)