linux-kernel - [PATCH 13/33 replaces 14/35 and 15/35] W1: w1_slave_read

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Message-ID: <20080413231537.GF15213@spacedout.fries.net>
Date:	Sun, 13 Apr 2008 18:15:37 -0500
From:	David Fries <david@...es.net>
To:	Evgeniy Polyakov <johnpol@....mipt.ru>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 13/33 replaces 14/35 and 15/35] W1: w1_slave_read_id multiple short read bug

===================================================================
This is an update to the previous set of patches, don't merge them
yet.  Some of the context was messed up and I don't expect patch to
apply the updates with the previous set cleanly.  I'll resubmit the
entire set if these updates look good.
===================================================================

This is more to point out the bug in w1_slave_read_id, the next patch
rewrites the routine.

w1.c 1.15
Reading at an offset other than zero, ie reading less than 8 bytes at
a time would result in reading the first bytes over and over until 8
bytes were returned.  Added the offset to the buffer.
- memcpy(buf, (u8 *)&sl->reg_num, count);
+ memcpy(buf, (u8 *)&sl->reg_num+off, count);
But there is a better way...

w1.c 1.16
Switching w1_slave_read_id from being a bin_attribute to a
device_attribute.  It only has to return 8 bytes per read and lets
kobject handle the buffering.  That simplifies the logic in
w1_slave_read_id.

Signed-off-by: David Fries <david@...es.net>
---
 drivers/w1/w1.c |   35 ++++++++++-------------------------
 1 files changed, 10 insertions(+), 25 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 5053bc8..c008493 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -104,35 +104,20 @@ static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *a
 	return sprintf(buf, "%s\n", sl->name);
 }
 
-static ssize_t w1_slave_read_id(struct kobject *kobj,
-				struct bin_attribute *bin_attr,
-				char *buf, loff_t off, size_t count)
+static ssize_t w1_slave_read_id(struct device *dev,
+	struct device_attribute *attr, char *buf)
 {
-	struct w1_slave *sl = kobj_to_w1_slave(kobj);
-
-	if (off > 8) {
-		count = 0;
-	} else {
-		if (off + count > 8)
-			count = 8 - off;
-
-		memcpy(buf, (u8 *)&sl->reg_num, count);
-	}
+	struct w1_slave *sl = dev_to_w1_slave(dev);
+	ssize_t count=sizeof(sl->reg_num);
 
+	memcpy(buf, (u8 *)&sl->reg_num, count);
 	return count;
 }
 
 static struct device_attribute w1_slave_attr_name =
 	__ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
-
-static struct bin_attribute w1_slave_attr_bin_id = {
-      .attr = {
-              .name = "id",
-              .mode = S_IRUGO,
-      },
-      .size = 8,
-      .read = w1_slave_read_id,
-};
+static struct device_attribute w1_slave_attr_id =
+	__ATTR(id, S_IRUGO, w1_slave_read_id, NULL);
 
 /* Default family */
 
@@ -642,7 +627,7 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
 	}
 
 	/* Create "id" entry */
-	err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
+	err = device_create_file(&sl->dev, &w1_slave_attr_id);
 	if (err < 0) {
 		dev_err(&sl->dev,
 			"sysfs file creation for [%s] failed. err=%d\n",
@@ -664,7 +649,7 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
 	return 0;
 
 out_rem2:
-	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
+	device_remove_file(&sl->dev, &w1_slave_attr_id);
 out_rem1:
 	device_remove_file(&sl->dev, &w1_slave_attr_name);
 out_unreg:
@@ -746,7 +731,7 @@ void w1_slave_detach(struct w1_slave *sl)
 	msg.type = W1_SLAVE_REMOVE;
 	w1_netlink_send(sl->master, &msg);
 
-	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
+	device_remove_file(&sl->dev, &w1_slave_attr_id);
 	device_remove_file(&sl->dev, &w1_slave_attr_name);
 	device_unregister(&sl->dev);
 
-- 
1.4.4.4

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