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Date: Tue, 7 Jul 2020 14:24:26 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, saeedm@...lanox.com,
michael.chan@...adcom.com, edwin.peer@...adcom.com,
emil.s.tantilov@...el.com, alexander.h.duyck@...ux.intel.com,
jeffrey.t.kirsher@...el.com, tariqt@...lanox.com, mkubecek@...e.cz,
Jakub Kicinski <kuba@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Chucheng Luo <luochucheng@...o.com>
Subject: [PATCH net-next 1/9] debugfs: make sure we can remove u32_array files cleanly
debugfs_create_u32_array() allocates a small structure to wrap
the data and size information about the array. If users ever
try to remove the file this leads to a leak since nothing ever
frees this wrapper.
That said there are no upstream users of debugfs_create_u32_array()
that'd remove a u32 array file (we only have one u32 array user in
CMA), so there is no real bug here.
Make callers pass a wrapper they allocated. This way the lifetime
management of the wrapper is on the caller, and we can avoid the
potential leak in debugfs.
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC: Marek Szyprowski <m.szyprowski@...sung.com>
CC: Chucheng Luo <luochucheng@...o.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
Documentation/filesystems/debugfs.rst | 12 ++++++++----
fs/debugfs/file.c | 27 +++++++--------------------
include/linux/debugfs.h | 12 +++++++++---
mm/cma.h | 3 +++
mm/cma_debug.c | 7 ++++---
5 files changed, 31 insertions(+), 30 deletions(-)
diff --git a/Documentation/filesystems/debugfs.rst b/Documentation/filesystems/debugfs.rst
index 1da7a4b7383d..728ab57a611a 100644
--- a/Documentation/filesystems/debugfs.rst
+++ b/Documentation/filesystems/debugfs.rst
@@ -185,13 +185,17 @@ byte offsets over a base for the register block.
If you want to dump an u32 array in debugfs, you can create file with::
+ struct debugfs_u32_array {
+ u32 *array;
+ u32 n_elements;
+ };
+
void debugfs_create_u32_array(const char *name, umode_t mode,
struct dentry *parent,
- u32 *array, u32 elements);
+ struct debugfs_u32_array *array);
-The "array" argument provides data, and the "elements" argument is
-the number of elements in the array. Note: Once array is created its
-size can not be changed.
+The "array" argument wraps a pointer to the array's data and the number
+of its elements. Note: Once array is created its size can not be changed.
There is a helper function to create device related seq_file::
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index ae49a55bda00..d0ed71f37511 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -918,11 +918,6 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode,
}
EXPORT_SYMBOL_GPL(debugfs_create_blob);
-struct array_data {
- void *array;
- u32 elements;
-};
-
static size_t u32_format_array(char *buf, size_t bufsize,
u32 *array, int array_size)
{
@@ -943,8 +938,8 @@ static size_t u32_format_array(char *buf, size_t bufsize,
static int u32_array_open(struct inode *inode, struct file *file)
{
- struct array_data *data = inode->i_private;
- int size, elements = data->elements;
+ struct debugfs_u32_array *data = inode->i_private;
+ int size, elements = data->n_elements;
char *buf;
/*
@@ -959,7 +954,7 @@ static int u32_array_open(struct inode *inode, struct file *file)
buf[size] = 0;
file->private_data = buf;
- u32_format_array(buf, size, data->array, data->elements);
+ u32_format_array(buf, size, data->array, data->n_elements);
return nonseekable_open(inode, file);
}
@@ -996,8 +991,7 @@ static const struct file_operations u32_array_fops = {
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
- * @array: u32 array that provides data.
- * @elements: total number of elements in the array.
+ * @array: wrapper struct containing data pointer and size of the array.
*
* This function creates a file in debugfs with the given name that exports
* @array as data. If the @mode variable is so set it can be read from.
@@ -1005,17 +999,10 @@ static const struct file_operations u32_array_fops = {
* Once array is created its size can not be changed.
*/
void debugfs_create_u32_array(const char *name, umode_t mode,
- struct dentry *parent, u32 *array, u32 elements)
+ struct dentry *parent,
+ struct debugfs_u32_array *array)
{
- struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL);
-
- if (data == NULL)
- return;
-
- data->array = array;
- data->elements = elements;
-
- debugfs_create_file_unsafe(name, mode, parent, data, &u32_array_fops);
+ debugfs_create_file_unsafe(name, mode, parent, array, &u32_array_fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32_array);
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index 63cb3606dea7..851dd1f9a8a5 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -38,6 +38,11 @@ struct debugfs_regset32 {
struct device *dev; /* Optional device for Runtime PM */
};
+struct debugfs_u32_array {
+ u32 *array;
+ u32 n_elements;
+};
+
extern struct dentry *arch_debugfs_dir;
#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
@@ -136,7 +141,8 @@ void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
int nregs, void __iomem *base, char *prefix);
void debugfs_create_u32_array(const char *name, umode_t mode,
- struct dentry *parent, u32 *array, u32 elements);
+ struct dentry *parent,
+ struct debugfs_u32_array *array);
struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,
struct dentry *parent,
@@ -316,8 +322,8 @@ static inline bool debugfs_initialized(void)
}
static inline void debugfs_create_u32_array(const char *name, umode_t mode,
- struct dentry *parent, u32 *array,
- u32 elements)
+ struct dentry *parent,
+ struct debugfs_u32_array *array)
{
}
diff --git a/mm/cma.h b/mm/cma.h
index 33c0b517733c..6698fa63279b 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -2,6 +2,8 @@
#ifndef __MM_CMA_H__
#define __MM_CMA_H__
+#include <linux/debugfs.h>
+
struct cma {
unsigned long base_pfn;
unsigned long count;
@@ -11,6 +13,7 @@ struct cma {
#ifdef CONFIG_CMA_DEBUGFS
struct hlist_head mem_head;
spinlock_t mem_head_lock;
+ struct debugfs_u32_array dfs_bitmap;
#endif
const char *name;
};
diff --git a/mm/cma_debug.c b/mm/cma_debug.c
index 4e6cbe2f586e..d5bf8aa34fdc 100644
--- a/mm/cma_debug.c
+++ b/mm/cma_debug.c
@@ -164,7 +164,6 @@ static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry)
{
struct dentry *tmp;
char name[16];
- int u32s;
scnprintf(name, sizeof(name), "cma-%s", cma->name);
@@ -180,8 +179,10 @@ static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry)
debugfs_create_file("used", 0444, tmp, cma, &cma_used_fops);
debugfs_create_file("maxchunk", 0444, tmp, cma, &cma_maxchunk_fops);
- u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32));
- debugfs_create_u32_array("bitmap", 0444, tmp, (u32 *)cma->bitmap, u32s);
+ cma->dfs_bitmap.array = (u32 *)cma->bitmap;
+ cma->dfs_bitmap.n_elements = DIV_ROUND_UP(cma_bitmap_maxno(cma),
+ BITS_PER_BYTE * sizeof(u32));
+ debugfs_create_u32_array("bitmap", 0444, tmp, &cma->dfs_bitmap);
}
static int __init cma_debugfs_init(void)
--
2.26.2
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