linux-kernel - [PATCH] Sort module list - use ppos instead of m->private

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Date:	Fri, 24 Aug 2007 11:39:33 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Al Viro <viro@....linux.org.uk>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Randy Dunlap <rddunlap@...l.org>,
	Martin Bligh <mbligh@...gle.com>
Subject: [PATCH] Sort module list - use ppos instead of m->private

Sort modules list - use ppos instead of m->private

When reading the data by small chunks (i.e. byte by byte), the index (ppos) is
incremented by seq_read() directly and no "next" callback is called when going
to the next module.

Therefore, use ppos instead of m->private to deal with the fact that this index
is incremented directly to pass to the next module in seq_read() after the
buffer has been emptied.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
---
 fs/seq_file.c            |   17 +++++++++--------
 include/linux/seq_file.h |    4 ++--
 kernel/module.c          |    6 ++----
 3 files changed, 13 insertions(+), 14 deletions(-)

Index: linux-2.6-lttng/kernel/module.c
===================================================================
--- linux-2.6-lttng.orig/kernel/module.c	2007-08-24 11:34:36.000000000 -0400
+++ linux-2.6-lttng/kernel/module.c	2007-08-24 11:35:40.000000000 -0400
@@ -2418,14 +2418,12 @@ unsigned long module_kallsyms_lookup_nam
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
 	mutex_lock(&module_mutex);
-	if (!*pos)
-		m->private = NULL;
-	return seq_sorted_list_start(&modules, m->private);
+	return seq_sorted_list_start(&modules, (void*)(long)pos);
 }
 
 static void *m_next(struct seq_file *m, void *p, loff_t *pos)
 {
-	return seq_sorted_list_next(p, &modules, &m->private);
+	return seq_sorted_list_next(p, &modules, (void**)pos);
 }
 
 static void m_stop(struct seq_file *m, void *p)
Index: linux-2.6-lttng/include/linux/seq_file.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/seq_file.h	2007-08-24 11:34:01.000000000 -0400
+++ linux-2.6-lttng/include/linux/seq_file.h	2007-08-24 11:34:59.000000000 -0400
@@ -73,9 +73,9 @@ extern struct list_head *seq_list_next(v
  * seq_sorted_list_start_head().
  */
 extern struct list_head *seq_sorted_list_start(struct list_head *head,
-		void *pos);
+		void **ppos);
 extern struct list_head *seq_sorted_list_start_head(struct list_head *head,
-		void *pos);
+		void **ppos);
 /*
  * next must be called with an existing p node
  */
Index: linux-2.6-lttng/fs/seq_file.c
===================================================================
--- linux-2.6-lttng.orig/fs/seq_file.c	2007-08-24 11:34:01.000000000 -0400
+++ linux-2.6-lttng/fs/seq_file.c	2007-08-24 11:34:59.000000000 -0400
@@ -501,27 +501,28 @@ struct list_head *seq_list_next(void *v,
 
 EXPORT_SYMBOL(seq_list_next);
 
-struct list_head *seq_sorted_list_start(struct list_head *head, void *pos)
+struct list_head *seq_sorted_list_start(struct list_head *head, void **ppos)
 {
 	struct list_head *lh;
 
 	list_for_each(lh, head)
-		if ((void*)lh >= pos)
-			return lh;
+		if ((void*)lh >= *ppos)
+			return *ppos = lh;
 	return NULL;
 }
 
 EXPORT_SYMBOL(seq_sorted_list_start);
 
-struct list_head *seq_sorted_list_start_head(struct list_head *head, void *pos)
+struct list_head *seq_sorted_list_start_head(struct list_head *head,
+		void **ppos)
 {
 	struct list_head *lh;
 
-	if (!pos)
-		return head;
+	if (!ppos)
+		return *ppos = head;
 	list_for_each(lh, head)
-		if ((void*)lh >= pos)
-			return lh->prev;
+		if ((void*)lh >= *ppos)
+			return *ppos = lh->prev;
 	return NULL;
 }
 
-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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