driver core: debug for bad dev_attr_show() return value.

Try to find the culprit who caused
http://bugzilla.kernel.org/show_bug.cgi?id=10150

Cc: <balajirrao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 12 insertions, 1 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 7de543d1d0b4..24198ad01976 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -19,6 +19,7 @@
 #include <linux/kdev_t.h>
 #include <linux/notifier.h>
 #include <linux/genhd.h>
+#include <linux/kallsyms.h>
 #include <asm/semaphore.h>
 
 #include "base.h"
@@ -68,6 +69,10 @@ static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
 
         if (dev_attr->show)
                 ret = dev_attr->show(dev, dev_attr, buf);
+        if (ret >= (ssize_t)PAGE_SIZE) {
+                print_symbol("dev_attr_show: %s returned bad count\n",
+                                (unsigned long)dev_attr->show);
+        }
         return ret;
 }
 
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index a271c87c4472..baa663e69388 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -12,6 +12,7 @@
 
 #include <linux/module.h>
 #include <linux/kobject.h>
+#include <linux/kallsyms.h>
 #include <linux/namei.h>
 #include <linux/poll.h>
 #include <linux/list.h>
@@ -86,7 +87,12 @@ static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer
          * The code works fine with PAGE_SIZE return but it's likely to
          * indicate truncated result or overflow in normal use cases.
          */
-        BUG_ON(count >= (ssize_t)PAGE_SIZE);
+        if (count >= (ssize_t)PAGE_SIZE) {
+                print_symbol("fill_read_buffer: %s returned bad count\n",
+                        (unsigned long)ops->show);
+                /* Try to struggle along */
+                count = PAGE_SIZE - 1;
+        }
         if (count >= 0) {
                 buffer->needs_read_fill = 0;
                 buffer->count = count;