ieee1394: shrink tlabel pools, remove tpool semaphores

This patch reduces the size of struct hpsb_host and also removes
semaphores from ieee1394_transactions.c.  On i386, struct hpsb_host
shrinks from 10656 bytes to 6688 bytes.  This is accomplished by
 - using a single wait_queue for hpsb_get_tlabel instead of many
   instances of semaphores,
 - using a single lock to serialize access to all tlabel pools (the
   protected code regions are small, i.e. lock contention very low),
 - omitting the sysfs attribute tlabels_allocations.

Drawback:  In the rare case that a process needs to sleep because all
transaction labels for the node are temporarily exhausted, it is also
woken up if a tlabel for a different node became free, checks for an
available tlabel, and is put to sleep again.  The check is not costly
and the situation occurs extremely rarely.  (Tlabels are typically
only exhausted if there was no context switch to the khpsbpkt thread
which recycles tlables.)  Therefore the benefit of reduced tpool size
outweighs this drawback.

The sysfs attributes tlabels_free and tlabels_mask are not compiled
anymore unless CONFIG_IEEE1394_VERBOSEDEBUG is set.

The by far biggest member of struct hpsb_host, the struct csr_control
csr (5272 bytes on i386), is now placed at the end of struct hpsb_host.

Note, hpsb_get_tlabel calls the macro wait_event_interruptible with a
condition argument which has a side effect (allocation of a tlabel and
manipulation of the packet).  This side effect happens only if the
condition is true.  The patch relies on wait_event_interruptible not
evaluating the condition again after it became true.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 26 insertions, 17 deletions

diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index f8f6079cc48c..eabc51b23c0b 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/drivers/ieee1394/nodemgr.c
@@ -327,34 +327,44 @@ static ssize_t fw_show_ne_bus_options(struct device *dev, struct device_attribut
 static DEVICE_ATTR(bus_options,S_IRUGO,fw_show_ne_bus_options,NULL);
 
 
-/* tlabels_free, tlabels_allocations, tlabels_mask are read non-atomically
- * here, therefore displayed values may be occasionally wrong. */
-static ssize_t fw_show_ne_tlabels_free(struct device *dev, struct device_attribute *attr, char *buf)
+#ifdef HPSB_DEBUG_TLABELS
+static ssize_t fw_show_ne_tlabels_free(struct device *dev,
+                                       struct device_attribute *attr, char *buf)
 {
         struct node_entry *ne = container_of(dev, struct node_entry, device);
-        return sprintf(buf, "%d\n", 64 - bitmap_weight(ne->tpool->pool, 64));
-}
-static DEVICE_ATTR(tlabels_free,S_IRUGO,fw_show_ne_tlabels_free,NULL);
+        unsigned long flags;
+        unsigned long *tp = ne->host->tl_pool[NODEID_TO_NODE(ne->nodeid)].map;
+        int tf;
 
+        spin_lock_irqsave(&hpsb_tlabel_lock, flags);
+        tf = 64 - bitmap_weight(tp, 64);
+        spin_unlock_irqrestore(&hpsb_tlabel_lock, flags);
 
-static ssize_t fw_show_ne_tlabels_allocations(struct device *dev, struct device_attribute *attr, char *buf)
-{
-        struct node_entry *ne = container_of(dev, struct node_entry, device);
-        return sprintf(buf, "%u\n", ne->tpool->allocations);
+        return sprintf(buf, "%d\n", tf);
 }
-static DEVICE_ATTR(tlabels_allocations,S_IRUGO,fw_show_ne_tlabels_allocations,NULL);
+static DEVICE_ATTR(tlabels_free,S_IRUGO,fw_show_ne_tlabels_free,NULL);
 
 
-static ssize_t fw_show_ne_tlabels_mask(struct device *dev, struct device_attribute *attr, char *buf)
+static ssize_t fw_show_ne_tlabels_mask(struct device *dev,
+                                       struct device_attribute *attr, char *buf)
 {
         struct node_entry *ne = container_of(dev, struct node_entry, device);
+        unsigned long flags;
+        unsigned long *tp = ne->host->tl_pool[NODEID_TO_NODE(ne->nodeid)].map;
+        u64 tm;
+
+        spin_lock_irqsave(&hpsb_tlabel_lock, flags);
 #if (BITS_PER_LONG <= 32)
-        return sprintf(buf, "0x%08lx%08lx\n", ne->tpool->pool[0], ne->tpool->pool[1]);
+        tm = ((u64)tp[0] << 32) + tp[1];
 #else
-        return sprintf(buf, "0x%016lx\n", ne->tpool->pool[0]);
+        tm = tp[0];
 #endif
+        spin_unlock_irqrestore(&hpsb_tlabel_lock, flags);
+
+        return sprintf(buf, "0x%016llx\n", tm);
 }
 static DEVICE_ATTR(tlabels_mask, S_IRUGO, fw_show_ne_tlabels_mask, NULL);
+#endif /* HPSB_DEBUG_TLABELS */
 
 
 static ssize_t fw_set_ignore_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
@@ -461,9 +471,10 @@ static struct device_attribute *const fw_ne_attrs[] = {
         &dev_attr_ne_vendor_id,
         &dev_attr_ne_nodeid,
         &dev_attr_bus_options,
+#ifdef HPSB_DEBUG_TLABELS
         &dev_attr_tlabels_free,
-        &dev_attr_tlabels_allocations,
         &dev_attr_tlabels_mask,
+#endif
 };
 
 
@@ -782,8 +793,6 @@ static struct node_entry *nodemgr_create_node(octlet_t guid, struct csr1212_csr
         if (!ne)
                 return NULL;
 
-        ne->tpool = &host->tpool[nodeid & NODE_MASK];
-
         ne->host = host;
         ne->nodeid = nodeid;
         ne->generation = generation;