[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>

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;
 }
 

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)