[PATCH] Add find_domain_rcu_lock() and domain_rcu_unlock functions

* [PATCH] Add find_domain_rcu_lock() and domain_rcu_unlock functions
@ 2007-02-09 19:29 Santos, Jose Renato G
  2007-02-21 16:33 ` Keir Fraser
  0 siblings, 1 reply; 4+ messages in thread
From: Santos, Jose Renato G @ 2007-02-09 19:29 UTC (permalink / raw)
  To: Keir Fraser, xen-devel

[-- Attachment #1: Type: text/plain, Size: 476 bytes --]

Sorry,
Forgot to attach the file in previous message

Renato 

> -----Original Message-----
> From: Santos, Jose Renato G 
> Sent: Friday, February 09, 2007 11:28 AM
> To: Keir Fraser; xen-devel@lists.xensource.com
> Subject: [PATCH] Add find_domain_rcu_lock() and 
> domain_rcu_unlock functions
> 
> 
> Keir,
> 
> This patch adds find_domain_rcu_lock() and 
> domain_rcu_unlock() functions that we have discussed before.
> 
> Thanks 
> 
> Renato
> 
> 

[-- Attachment #2: find_domain_rcu.patch --]
[-- Type: application/octet-stream, Size: 2353 bytes --]

Signed-off-by: Jose Renato Santos <jsantos@hpl.hp.com>

# HG changeset patch
# User root@lsnpsvr3.hpl.hp.com
# Date 1170878467 28800
# Node ID c768b2d65ef5f8da47826c3ebe236b49acff97a9
# Parent  d5d00004a11e8ce494aea869ebf3c23fd9f87e38
[XEN] add find_domain_rcu_lock() and domain_rcu_unlock()

diff -r d5d00004a11e -r c768b2d65ef5 xen/common/domain.c

--- a/xen/common/domain.c	Wed Feb 07 09:48:39 2007 -0800
+++ b/xen/common/domain.c	Wed Feb 07 12:01:07 2007 -0800
@@ -233,6 +233,30 @@ struct domain *get_domain_by_id(domid_t 
     return d;
 }
 
+/* find_domain_rcu_lock() is more efficient than get_domain_by_id()
+ * This is the preferred function if the returned domain reference
+ * is short lived,  but it cannot be used if the domain reference needs 
+ * to be kept beyond the current xen invocation.
+ * It is good practice to call domain_rcu_unlock() when the returned
+ * domain reference is no longer needed. 
+ */
+struct domain *find_domain_rcu_lock(domid_t dom)
+{
+    struct domain *d;
+
+    rcu_read_lock();
+    d = rcu_dereference(domain_hash[DOMAIN_HASH(dom)]);
+    while ( d != NULL )
+    {
+        if ( d->domain_id == dom )
+            return d;
+        d = rcu_dereference(d->next_in_hashbucket);
+    }
+    rcu_read_unlock();
+
+    return NULL;
+}
+
 
 void domain_kill(struct domain *d)
 {
diff -r d5d00004a11e -r c768b2d65ef5 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h	Wed Feb 07 09:48:39 2007 -0800
+++ b/xen/include/xen/sched.h	Wed Feb 07 12:01:07 2007 -0800
@@ -278,6 +278,21 @@ int construct_dom0(
     unsigned long image_start, unsigned long image_len, 
     unsigned long initrd_start, unsigned long initrd_len,
     char *cmdline);
+
+/* find_domain_rcu_lock() is more efficient than get_domain_by_id()
+ * This is the preferred function if the returned domain reference
+ * is short lived,  but it cannot be used if the domain reference needs 
+ * to be kept beyond the current xen invocation.
+ * It is good practice to call domain_rcu_unlock() when the returned
+ * domain reference is no longer needed.
+ */
+struct domain *find_domain_rcu_lock(domid_t dom);
+
+/* unlock rcu reader side section locked by find_domain_rcu_lock() */ 
+static inline void domain_rcu_unlock(void)
+{
+    rcu_read_unlock();
+}
 
 struct domain *get_domain_by_id(domid_t dom);
 void domain_destroy(struct domain *d);

[-- Attachment #3: Type: text/plain, Size: 138 bytes --]

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

^ permalink raw reply	[flat|nested] 4+ messages in thread