[S390] cio: replace subchannel evaluation queue with bitmap

Use a bitmap for indicating which subchannels require evaluation
instead of allocating memory for each evaluation request. This
approach reduces memory consumption during recovery in case of
massive evaluation request occurrence and removes the need for
memory allocation failure handling.

Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 112 insertions, 0 deletions

diff --git a/drivers/s390/cio/idset.c b/drivers/s390/cio/idset.c
new file mode 100644
index 000000000000..16ea828e99f7
--- /dev/null
+++ b/drivers/s390/cio/idset.c
@@ -0,0 +1,112 @@
+/*
+ *  drivers/s390/cio/idset.c
+ *
+ *    Copyright IBM Corp. 2007
+ *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
+ */
+
+#include <linux/slab.h>
+#include <asm/bitops.h>
+#include "idset.h"
+#include "css.h"
+
+struct idset {
+        int num_ssid;
+        int num_id;
+        unsigned long bitmap[0];
+};
+
+static inline unsigned long bitmap_size(int num_ssid, int num_id)
+{
+        return __BITOPS_WORDS(num_ssid * num_id) * sizeof(unsigned long);
+}
+
+static struct idset *idset_new(int num_ssid, int num_id)
+{
+        struct idset *set;
+
+        set = kzalloc(sizeof(struct idset) + bitmap_size(num_ssid, num_id),
+                      GFP_KERNEL);
+        if (set) {
+                set->num_ssid = num_ssid;
+                set->num_id = num_id;
+        }
+        return set;
+}
+
+void idset_free(struct idset *set)
+{
+        kfree(set);
+}
+
+void idset_clear(struct idset *set)
+{
+        memset(set->bitmap, 0, bitmap_size(set->num_ssid, set->num_id));
+}
+
+void idset_fill(struct idset *set)
+{
+        memset(set->bitmap, 0xff, bitmap_size(set->num_ssid, set->num_id));
+}
+
+static inline void idset_add(struct idset *set, int ssid, int id)
+{
+        set_bit(ssid * set->num_id + id, set->bitmap);
+}
+
+static inline void idset_del(struct idset *set, int ssid, int id)
+{
+        clear_bit(ssid * set->num_id + id, set->bitmap);
+}
+
+static inline int idset_contains(struct idset *set, int ssid, int id)
+{
+        return test_bit(ssid * set->num_id + id, set->bitmap);
+}
+
+static inline int idset_get_first(struct idset *set, int *ssid, int *id)
+{
+        int bitnum;
+
+        bitnum = find_first_bit(set->bitmap, set->num_ssid * set->num_id);
+        if (bitnum >= set->num_ssid * set->num_id)
+                return 0;
+        *ssid = bitnum / set->num_id;
+        *id = bitnum % set->num_id;
+        return 1;
+}
+
+struct idset *idset_sch_new(void)
+{
+        return idset_new(__MAX_SSID + 1, __MAX_SUBCHANNEL + 1);
+}
+
+void idset_sch_add(struct idset *set, struct subchannel_id schid)
+{
+        idset_add(set, schid.ssid, schid.sch_no);
+}
+
+void idset_sch_del(struct idset *set, struct subchannel_id schid)
+{
+        idset_del(set, schid.ssid, schid.sch_no);
+}
+
+int idset_sch_contains(struct idset *set, struct subchannel_id schid)
+{
+        return idset_contains(set, schid.ssid, schid.sch_no);
+}
+
+int idset_sch_get_first(struct idset *set, struct subchannel_id *schid)
+{
+        int ssid = 0;
+        int id = 0;
+        int rc;
+
+        rc = idset_get_first(set, &ssid, &id);
+        if (rc) {
+                init_subchannel_id(schid);
+                schid->ssid = ssid;
+                schid->sch_no = id;
+        }
+        return rc;
+}