[llvmlinux] Fwd: Patch 'usb: gadget: FunctionFS: Remove VLAIS usage from gadget code' applied to my tree

Behan Webster behanw at converseincode.com
Wed Dec 18 18:31:37 UTC 2013


Just FYI

Behan

-------- Original Message --------
Subject: 	Patch 'usb: gadget: FunctionFS: Remove VLAIS usage from gadget
code' applied to my tree
Date: 	Wed, 18 Dec 2013 09:28:59 -0600
From: 	<balbi at ti.com>
To: 	<andrzej.p at samsung.com>
CC: 	<charlebm at gmail.com>, <behanw at converseincode.com>,
<andrzej.p at samsung.com>, <kyungmin.park at samsung.com>,
<mina86 at mina86.com>, <balbi at ti.com>, <balbi at ti.com>



Hi,

This is a note to let you know that the patch:

	usb: gadget: FunctionFS: Remove VLAIS usage from gadget code

has been applied to my tree and can be found at:

	http://bit.ly/19kVW3d

a snapshot of the tree can be downloaded from:

	http://bit.ly/1fazUAx

Note that it might take up to 20 minutes for kernel.org to synchronize
the changes to its frontend servers.

If you have any concerns, please let me know by replying to this mail.

>From e6f3862fa1ecea6579dd1727869655e88be7a5ef Mon Sep 17 00:00:00 2001
From: Andrzej Pietrasiewicz <andrzej.p at samsung.com>
Date: Tue, 3 Dec 2013 15:15:30 +0100
Subject: [PATCH] usb: gadget: FunctionFS: Remove VLAIS usage from gadget code

The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). This alternate patch calculates offsets into the kmalloc-ed
memory buffer using macros. The previous patch required multiple kmalloc and
kfree calls. This version uses "group" vs "struct" since it really is not a
struct and is essentially a group of VLA in a common allocated block. This
version also fixes the issues pointed out by Andrzej Pietrasiewicz and
Michal Nazarewicz.

Signed-off-by: Mark Charlebois <charlebm at gmail.com>
Signed-off-by: Behan Webster <behanw at converseincode.com>

[elimination of miexed declaration and code, checkpatch cleanup]
[fixes after Michal's review]
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p at samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
Acked-by: Michal Nazarewicz <mina86 at mina86.com>
Signed-off-by: Felipe Balbi <balbi at ti.com>
---
 drivers/usb/gadget/f_fs.c | 116 ++++++++++++++++++++++++++++++----------------
 1 file changed, 76 insertions(+), 40 deletions(-)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 3494043..91b94b1 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -30,6 +30,31 @@
 
 #define FUNCTIONFS_MAGIC	0xa647361 /* Chosen by a honest dice roll ;) */
 
+/* Variable Length Array Macros **********************************************/
+#define vla_group(groupname) size_t groupname##__next = 0
+#define vla_group_size(groupname) groupname##__next
+
+#define vla_item(groupname, type, name, n) \
+	size_t groupname##_##name##__offset = ({			       \
+		size_t align_mask = __alignof__(type) - 1;		       \
+		size_t offset = (groupname##__next + align_mask) & ~align_mask;\
+		size_t size = (n) * sizeof(type);			       \
+		groupname##__next = offset + size;			       \
+		offset;							       \
+	})
+
+#define vla_item_with_sz(groupname, type, name, n) \
+	size_t groupname##_##name##__sz = (n) * sizeof(type);		       \
+	size_t groupname##_##name##__offset = ({			       \
+		size_t align_mask = __alignof__(type) - 1;		       \
+		size_t offset = (groupname##__next + align_mask) & ~align_mask;\
+		size_t size = groupname##_##name##__sz;			       \
+		groupname##__next = offset + size;			       \
+		offset;							       \
+	})
+
+#define vla_ptr(ptr, groupname, name) \
+	((void *) ((char *)ptr + groupname##_##name##__offset))
 
 /* Debugging ****************************************************************/
 
@@ -1902,30 +1927,34 @@ static int __ffs_data_got_strings(struct ffs_data *ffs,
 
 	/* Allocate everything in one chunk so there's less maintenance. */
 	{
-		struct {
-			struct usb_gadget_strings *stringtabs[lang_count + 1];
-			struct usb_gadget_strings stringtab[lang_count];
-			struct usb_string strings[lang_count*(needed_count+1)];
-		} *d;
 		unsigned i = 0;
+		vla_group(d);
+		vla_item(d, struct usb_gadget_strings *, stringtabs,
+			lang_count + 1);
+		vla_item(d, struct usb_gadget_strings, stringtab, lang_count);
+		vla_item(d, struct usb_string, strings,
+			lang_count*(needed_count+1));
 
-		d = kmalloc(sizeof *d, GFP_KERNEL);
-		if (unlikely(!d)) {
+		char *vlabuf = kmalloc(vla_group_size(d), GFP_KERNEL);
+
+		if (unlikely(!vlabuf)) {
 			kfree(_data);
 			return -ENOMEM;
 		}
 
-		stringtabs = d->stringtabs;
-		t = d->stringtab;
+		/* Initialize the VLA pointers */
+		stringtabs = vla_ptr(vlabuf, d, stringtabs);
+		t = vla_ptr(vlabuf, d, stringtab);
 		i = lang_count;
 		do {
 			*stringtabs++ = t++;
 		} while (--i);
 		*stringtabs = NULL;
 
-		stringtabs = d->stringtabs;
-		t = d->stringtab;
-		s = d->strings;
+		/* stringtabs = vlabuf = d_stringtabs for later kfree */
+		stringtabs = vla_ptr(vlabuf, d, stringtabs);
+		t = vla_ptr(vlabuf, d, stringtab);
+		s = vla_ptr(vlabuf, d, strings);
 		strings = s;
 	}
 
@@ -2201,16 +2230,16 @@ static int ffs_func_bind(struct usb_configuration *c,
 	int ret;
 
 	/* Make it a single chunk, less management later on */
-	struct {
-		struct ffs_ep eps[ffs->eps_count];
-		struct usb_descriptor_header
-			*fs_descs[full ? ffs->fs_descs_count + 1 : 0];
-		struct usb_descriptor_header
-			*hs_descs[high ? ffs->hs_descs_count + 1 : 0];
-		short inums[ffs->interfaces_count];
-		char raw_descs[high ? ffs->raw_descs_length
-				    : ffs->raw_fs_descs_length];
-	} *data;
+	vla_group(d);
+	vla_item_with_sz(d, struct ffs_ep, eps, ffs->eps_count);
+	vla_item_with_sz(d, struct usb_descriptor_header *, fs_descs,
+		full ? ffs->fs_descs_count + 1 : 0);
+	vla_item_with_sz(d, struct usb_descriptor_header *, hs_descs,
+		high ? ffs->hs_descs_count + 1 : 0);
+	vla_item_with_sz(d, short, inums, ffs->interfaces_count);
+	vla_item_with_sz(d, char, raw_descs,
+		high ? ffs->raw_descs_length : ffs->raw_fs_descs_length);
+	char *vlabuf;
 
 	ENTER();
 
@@ -2218,21 +2247,28 @@ static int ffs_func_bind(struct usb_configuration *c,
 	if (unlikely(!(full | high)))
 		return -ENOTSUPP;
 
-	/* Allocate */
-	data = kmalloc(sizeof *data, GFP_KERNEL);
-	if (unlikely(!data))
+	/* Allocate a single chunk, less management later on */
+	vlabuf = kmalloc(vla_group_size(d), GFP_KERNEL);
+	if (unlikely(!vlabuf))
 		return -ENOMEM;
 
 	/* Zero */
-	memset(data->eps, 0, sizeof data->eps);
-	memcpy(data->raw_descs, ffs->raw_descs + 16, sizeof data->raw_descs);
-	memset(data->inums, 0xff, sizeof data->inums);
-	for (ret = ffs->eps_count; ret; --ret)
-		data->eps[ret].num = -1;
+	memset(vla_ptr(vlabuf, d, eps), 0, d_eps__sz);
+	memcpy(vla_ptr(vlabuf, d, raw_descs), ffs->raw_descs + 16,
+	       d_raw_descs__sz);
+	memset(vla_ptr(vlabuf, d, inums), 0xff, d_inums__sz);
+	for (ret = ffs->eps_count; ret; --ret) {
+		struct ffs_ep *ptr;
+
+		ptr = vla_ptr(vlabuf, d, eps);
+		ptr[ret].num = -1;
+	}
 
-	/* Save pointers */
-	func->eps             = data->eps;
-	func->interfaces_nums = data->inums;
+	/* Save pointers
+	 * d_eps == vlabuf, func->eps used to kfree vlabuf later
+	*/
+	func->eps             = vla_ptr(vlabuf, d, eps);
+	func->interfaces_nums = vla_ptr(vlabuf, d, inums);
 
 	/*
 	 * Go through all the endpoint descriptors and allocate
@@ -2240,10 +2276,10 @@ static int ffs_func_bind(struct usb_configuration *c,
 	 * numbers without worrying that it may be described later on.
 	 */
 	if (likely(full)) {
-		func->function.fs_descriptors = data->fs_descs;
+		func->function.fs_descriptors = vla_ptr(vlabuf, d, fs_descs);
 		ret = ffs_do_descs(ffs->fs_descs_count,
-				   data->raw_descs,
-				   sizeof data->raw_descs,
+				   vla_ptr(vlabuf, d, raw_descs),
+				   d_raw_descs__sz,
 				   __ffs_func_bind_do_descs, func);
 		if (unlikely(ret < 0))
 			goto error;
@@ -2252,10 +2288,10 @@ static int ffs_func_bind(struct usb_configuration *c,
 	}
 
 	if (likely(high)) {
-		func->function.hs_descriptors = data->hs_descs;
+		func->function.hs_descriptors = vla_ptr(vlabuf, d, hs_descs);
 		ret = ffs_do_descs(ffs->hs_descs_count,
-				   data->raw_descs + ret,
-				   (sizeof data->raw_descs) - ret,
+				   vla_ptr(vlabuf, d, raw_descs) + ret,
+				   d_raw_descs__sz - ret,
 				   __ffs_func_bind_do_descs, func);
 		if (unlikely(ret < 0))
 			goto error;
@@ -2268,7 +2304,7 @@ static int ffs_func_bind(struct usb_configuration *c,
 	 */
 	ret = ffs_do_descs(ffs->fs_descs_count +
 			   (high ? ffs->hs_descs_count : 0),
-			   data->raw_descs, sizeof data->raw_descs,
+			   vla_ptr(vlabuf, d, raw_descs), d_raw_descs__sz,
 			   __ffs_func_bind_do_nums, func);
 	if (unlikely(ret < 0))
 		goto error;
-- 
1.8.4.GIT



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