[PATCH] USB: Removing the use of VLAIS from the gadget driver

[behanw]

From: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>

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 patch removes the use of VLAIS in the gadget driver.

Signed-off-by: Mark Charlebois <charlebm@xxxxxxxxx>
Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
---
 drivers/usb/gadget/f_fs.c | 128 +++++++++++++++++++++++++++-------------------
 1 file changed, 76 insertions(+), 52 deletions(-)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index f394f29..4b872c4 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -30,7 +30,6 @@
 
 #define FUNCTIONFS_MAGIC	0xa647361 /* Chosen by a honest dice roll ;) */
 
-
 /* Debugging ****************************************************************/
 
 #ifdef VERBOSE_DEBUG
@@ -214,6 +213,8 @@ struct ffs_data {
 	/* ids in stringtabs are set in functionfs_bind() */
 	const void			*raw_strings;
 	struct usb_gadget_strings	**stringtabs;
+	struct usb_gadget_strings	*stringtab;
+	struct usb_string		*strings;
 
 	/*
 	 * File system's super block, write once when file system is
@@ -263,7 +264,10 @@ struct ffs_function {
 
 	struct ffs_ep			*eps;
 	u8				eps_revmap[16];
+	struct usb_descriptor_header	**fs_descs;
+	struct usb_descriptor_header	**hs_descs;
 	short				*interfaces_nums;
+	char				*raw_descs;
 
 	struct usb_function		function;
 };
@@ -1345,6 +1349,8 @@ static void ffs_data_clear(struct ffs_data *ffs)
 	kfree(ffs->raw_descs);
 	kfree(ffs->raw_strings);
 	kfree(ffs->stringtabs);
+	kfree(ffs->stringtab);
+	kfree(ffs->strings);
 }
 
 static void ffs_data_reset(struct ffs_data *ffs)
@@ -1357,6 +1363,8 @@ static void ffs_data_reset(struct ffs_data *ffs)
 	ffs->raw_descs = NULL;
 	ffs->raw_strings = NULL;
 	ffs->stringtabs = NULL;
+	ffs->stringtab = NULL;
+	ffs->strings = NULL;
 
 	ffs->raw_descs_length = 0;
 	ffs->raw_fs_descs_length = 0;
@@ -1528,12 +1536,10 @@ static void ffs_func_free(struct ffs_function *func)
 	ffs_data_put(func->ffs);
 
 	kfree(func->eps);
-	/*
-	 * eps and interfaces_nums are allocated in the same chunk so
-	 * only one free is required.  Descriptors are also allocated
-	 * in the same chunk.
-	 */
-
+	kfree(func->fs_descs);
+	kfree(func->hs_descs);
+	kfree(func->interfaces_nums);
+	kfree(func->raw_descs);
 	kfree(func);
 }
 
@@ -1907,33 +1913,35 @@ static int __ffs_data_got_strings(struct ffs_data *ffs,
 		return 0;
 	}
 
-	/* 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;
-
-		d = kmalloc(sizeof *d, GFP_KERNEL);
-		if (unlikely(!d)) {
+		usb_gadget_strings **stringtabs = NULL;
+		usb_gadget_strings *stringtab = NULL;
+		usb_string *strings = NULL;
+
+		stringtabs = kmalloc(sizeof(*stringtabs)*(lang_count + 1),
+			GFP_KERNEL);
+		stringtab = kmalloc(sizeof(*stringtab)*(lang_count),
+			GFP_KERNEL);
+		strings = kmalloc(sizeof(*strings)
+			* (lang_count * (needed_count + 1)), GFP_KERNEL);
+		if (unlikely(!stringtabs || !stringtab || !strings)) {
+			kfree(stringtabs);
+			kfree(stringtab);
+			kfree(strings);
 			kfree(_data);
 			return -ENOMEM;
 		}
-
-		stringtabs = d->stringtabs;
-		t = d->stringtab;
+		b = stringtabs;
+		t = stringtab;
 		i = lang_count;
 		do {
-			*stringtabs++ = t++;
+			*b++ = t++;
 		} while (--i);
-		*stringtabs = NULL;
+		*b = NULL;
 
-		stringtabs = d->stringtabs;
-		t = d->stringtab;
-		s = d->strings;
-		strings = s;
+		t = stringtab;
+		s = strings;
 	}
 
 	/* For each language */
@@ -1991,12 +1999,16 @@ static int __ffs_data_got_strings(struct ffs_data *ffs,
 
 	/* Done! */
 	ffs->stringtabs = stringtabs;
+	ffs->stringtab = stringtab;
+	ffs->strings = strings;
 	ffs->raw_strings = _data;
 
 	return 0;
 
 error_free:
 	kfree(stringtabs);
+	kfree(stringtab);
+	kfree(strings);
 error:
 	kfree(_data);
 	return -EINVAL;
@@ -2207,17 +2219,12 @@ 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;
+	struct ffs_ep *eps = NULL;
+	struct usb_descriptor_header **fs_descs = NULL;
+	struct usb_descriptor_header **hs_descs = NULL;
+	short *inums = NULL;
+	char *raw_descs = NULL;
+
 
 	ENTER();
 
@@ -2225,21 +2232,40 @@ 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))
+	size_t eps_sz = sizeof(*eps)*ffs->eps_count;
+	eps = kmalloc(eps_sz, GFP_KERNEL);
+	fs_descs = kmalloc(sizeof(*fs_descs)*
+			   (full ? ffs->fs_descs_count + 1 : 0), GFP_KERNEL);
+	hs_descs = kmalloc(sizeof(*hs_descs)*
+			   (high ? ffs->hs_descs_count + 1 : 0), GFP_KERNEL);
+	size_t inums_sz = sizeof(*inums)*ffs->interfaces_count;
+	inums = kmalloc(inums_sz, GFP_KERNEL);
+	size_t raw_descs_sz = sizeof(*raw_descs)*(high ? ffs->raw_descs_length :
+					ffs->raw_fs_descs_length);
+	raw_descs = kmalloc(raw_descs_sz, , GFP_KERNEL);
+
+	if (unlikely(!eps || !fs_descs || !hs_descs || !inums || !raw_descs)) {
+		kfree(eps);
+		kfree(fs_descs);
+		kfree(hs_descs);
+		kfree(inums);
+		kfree(raw_descs);
 		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);
+	memset(eps, 0, eps_sz);
+	memcpy(raw_descs, ffs->raw_descs + 16, raw_descs_sz);
+	memset(inums, 0xff, inums_sz);
 	for (ret = ffs->eps_count; ret; --ret)
-		data->eps[ret].num = -1;
+		eps[ret].num = -1;
 
 	/* Save pointers */
-	func->eps             = data->eps;
-	func->interfaces_nums = data->inums;
+	func->eps             = eps;
+	func->fs_descs        = fs_descs;
+	func->hs_descs        = hs_descs;
+	func->interfaces_nums = inums;
+	func->raw_descs       = raw_descs;
 
 	/*
 	 * Go through all the endpoint descriptors and allocate
@@ -2247,10 +2273,9 @@ 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 = fs_descs;
 		ret = ffs_do_descs(ffs->fs_descs_count,
-				   data->raw_descs,
-				   sizeof data->raw_descs,
+				   raw_descs, raw_descs_sz,
 				   __ffs_func_bind_do_descs, func);
 		if (unlikely(ret < 0))
 			goto error;
@@ -2259,10 +2284,9 @@ static int ffs_func_bind(struct usb_configuration *c,
 	}
 
 	if (likely(high)) {
-		func->function.hs_descriptors = data->hs_descs;
+		func->function.hs_descriptors = hs_descs;
 		ret = ffs_do_descs(ffs->hs_descs_count,
-				   data->raw_descs + ret,
-				   (sizeof data->raw_descs) - ret,
+				   raw_descs + ret, raw_descs_sz - ret,
 				   __ffs_func_bind_do_descs, func);
 	}
 
@@ -2273,7 +2297,7 @@ 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,
+			   raw_descs, raw_descs_sz,
 			   __ffs_func_bind_do_nums, func);
 	if (unlikely(ret < 0))
 		goto error;
-- 
1.8.1.2

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