[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>

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;
 }
 

drivers/s390/cio/chsc.h

@@ -57,6 +57,25 @@ struct chsc_ssd_info {
 	struct chp_id chpid[8];
 	u16 fla[8];
 };
+
+struct chsc_scpd {
+	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));
+
+
 extern int chsc_get_ssd_info(struct subchannel_id schid,
 			     struct chsc_ssd_info *ssd);
 extern int chsc_determine_css_characteristics(void);
@@ -70,8 +89,7 @@ int __chsc_do_secm(struct channel_subsystem *css, int enable);
 
 int chsc_chp_vary(struct chp_id chpid, int on);
 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);
 int chsc_determine_base_channel_path_desc(struct chp_id chpid,
 					  struct channel_path_desc *desc);
 void chsc_chp_online(struct chp_id chpid);

drivers/s390/cio/chsc_sch.c

@@ -688,25 +688,31 @@ out_free:
 
 static int chsc_ioctl_chpd(void __user *user_chpd)
 {
+	struct chsc_scpd *scpd_area;
 	struct chsc_cpd_info *chpd;
 	int ret;
 
 	chpd = kzalloc(sizeof(*chpd), GFP_KERNEL);
-	if (!chpd)
-		return -ENOMEM;
+	scpd_area = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!scpd_area || !chpd) {
+		ret = -ENOMEM;
+		goto out_free;
+	}
 	if (copy_from_user(chpd, user_chpd, sizeof(*chpd))) {
 		ret = -EFAULT;
 		goto out_free;
 	}
 	ret = chsc_determine_channel_path_desc(chpd->chpid, chpd->fmt,
 					       chpd->rfmt, chpd->c, chpd->m,
-					       &chpd->chpdb);
+					       scpd_area);
 	if (ret)
 		goto out_free;
+	memcpy(&chpd->chpdb, &scpd_area->response, scpd_area->response.length);
 	if (copy_to_user(user_chpd, chpd, sizeof(*chpd)))
 		ret = -EFAULT;
 out_free:
 	kfree(chpd);
+	free_page((unsigned long)scpd_area);
 	return ret;
 }