[PATCH] s390: multiple subchannel sets support

Add support for multiple subchannel sets.  Works with arbitrary devices in
subchannel set 1 and is transparent to device drivers.  Although currently
only two subchannel sets are available, this will work with the architectured
maximum number of subchannel sets as well.

Signed-off-by: Cornelia Huck <cohuck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 42 insertions, 14 deletions

diff --git a/drivers/s390/s390mach.c b/drivers/s390/s390mach.c
index 4191fd9d4d11..7dad597ff86e 100644
--- a/drivers/s390/s390mach.c
+++ b/drivers/s390/s390mach.c
@@ -23,7 +23,7 @@
 
 static struct semaphore m_sem;
 
-extern int css_process_crw(int);
+extern int css_process_crw(int, int);
 extern int chsc_process_crw(void);
 extern int chp_process_crw(int, int);
 extern void css_reiterate_subchannels(void);
@@ -49,9 +49,10 @@ s390_handle_damage(char *msg)
 static int
 s390_collect_crw_info(void *param)
 {
-        struct crw crw;
+        struct crw crw[2];
         int ccode, ret, slow;
         struct semaphore *sem;
+        unsigned int chain;
 
         sem = (struct semaphore *)param;
         /* Set a nice name. */
@@ -59,25 +60,50 @@ s390_collect_crw_info(void *param)
 repeat:
         down_interruptible(sem);
         slow = 0;
+        chain = 0;
         while (1) {
-                ccode = stcrw(&crw);
+                if (unlikely(chain > 1)) {
+                        struct crw tmp_crw;
+
+                        printk(KERN_WARNING"%s: Code does not support more "
+                               "than two chained crws; please report to "
+                               "linux390@de.ibm.com!\n", __FUNCTION__);
+                        ccode = stcrw(&tmp_crw);
+                        printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
+                               "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
+                               __FUNCTION__, tmp_crw.slct, tmp_crw.oflw,
+                               tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
+                               tmp_crw.erc, tmp_crw.rsid);
+                        printk(KERN_WARNING"%s: This was crw number %x in the "
+                               "chain\n", __FUNCTION__, chain);
+                        if (ccode != 0)
+                                break;
+                        chain = tmp_crw.chn ? chain + 1 : 0;
+                        continue;
+                }
+                ccode = stcrw(&crw[chain]);
                 if (ccode != 0)
                         break;
                 DBG(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
                     "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
-                    crw.slct, crw.oflw, crw.chn, crw.rsc, crw.anc,
-                    crw.erc, crw.rsid);
+                    crw[chain].slct, crw[chain].oflw, crw[chain].chn,
+                    crw[chain].rsc, crw[chain].anc, crw[chain].erc,
+                    crw[chain].rsid);
                 /* Check for overflows. */
-                if (crw.oflw) {
+                if (crw[chain].oflw) {
                         pr_debug("%s: crw overflow detected!\n", __FUNCTION__);
                         css_reiterate_subchannels();
+                        chain = 0;
                         slow = 1;
                         continue;
                 }
-                switch (crw.rsc) {
+                switch (crw[chain].rsc) {
                 case CRW_RSC_SCH:
-                        pr_debug("source is subchannel %04X\n", crw.rsid);
-                        ret = css_process_crw (crw.rsid);
+                        if (crw[0].chn && !chain)
+                                break;
+                        pr_debug("source is subchannel %04X\n", crw[0].rsid);
+                        ret = css_process_crw (crw[0].rsid,
+                                               chain ? crw[1].rsid : 0);
                         if (ret == -EAGAIN)
                                 slow = 1;
                         break;
@@ -85,18 +111,18 @@ repeat:
                         pr_debug("source is monitoring facility\n");
                         break;
                 case CRW_RSC_CPATH:
-                        pr_debug("source is channel path %02X\n", crw.rsid);
-                        switch (crw.erc) {
+                        pr_debug("source is channel path %02X\n", crw[0].rsid);
+                        switch (crw[0].erc) {
                         case CRW_ERC_IPARM: /* Path has come. */
-                                ret = chp_process_crw(crw.rsid, 1);
+                                ret = chp_process_crw(crw[0].rsid, 1);
                                 break;
                         case CRW_ERC_PERRI: /* Path has gone. */
                         case CRW_ERC_PERRN:
-                                ret = chp_process_crw(crw.rsid, 0);
+                                ret = chp_process_crw(crw[0].rsid, 0);
                                 break;
                         default:
                                 pr_debug("Don't know how to handle erc=%x\n",
-                                         crw.erc);
+                                         crw[0].erc);
                                 ret = 0;
                         }
                         if (ret == -EAGAIN)
@@ -115,6 +141,8 @@ repeat:
                         pr_debug("unknown source\n");
                         break;
                 }
+                /* chain is always 0 or 1 here. */
+                chain = crw[chain].chn ? chain + 1 : 0;
         }
         if (slow)
                 queue_work(slow_path_wq, &slow_path_work);