Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755788Ab3IYVYd (ORCPT ); Wed, 25 Sep 2013 17:24:33 -0400 Received: from mail-pa0-f53.google.com ([209.85.220.53]:56659 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754993Ab3IYVYb (ORCPT ); Wed, 25 Sep 2013 17:24:31 -0400 From: charlebm@gmail.com To: balbi@ti.com Cc: Mark Charlebois , Behan Webster , Linus Torvalds , Greg Kroah-Hartman , USB list , Linux Kernel Mailing List , Andrzej Pietrasiewicz Subject: [PATCH] Remove VLAIS usage from gadget code - alternate patch Date: Wed, 25 Sep 2013 14:23:37 -0700 Message-Id: <1380144217-17015-1-git-send-email-charlebm@gmail.com> X-Mailer: git-send-email 1.8.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6408 Lines: 198 From: Mark Charlebois 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. Signed-off-by: Mark Charlebois Signed-off-by: Behan Webster --- --- linux.orig/drivers/usb/gadget/f_fs.c +++ linux/drivers/usb/gadget/f_fs.c @@ -30,6 +30,21 @@ #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 = \ + (groupname##__##next + __alignof__(type) - 1) & \ + ~(__alignof__(type) - 1); \ + size_t groupname##_##name##__##sz = (n) * sizeof(type); \ + type * groupname##_##name = ({ \ + groupname##__##next = groupname##_##name##__##offset + \ + groupname##_##name##__##sz; NULL;}) + +#define vla_ptr(ptr,groupname,name) groupname##_##name = \ + (__typeof__(groupname##_##name))&ptr[groupname##_##name##__##offset] /* Debugging ****************************************************************/ @@ -1909,30 +1924,38 @@ /* 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)); + + char *vlabuf = kmalloc(vla_group_size(d), GFP_KERNEL); - d = kmalloc(sizeof *d, GFP_KERNEL); - if (unlikely(!d)) { + if (unlikely(!vlabuf)) { kfree(_data); return -ENOMEM; } - stringtabs = d->stringtabs; - t = d->stringtab; + /* Initialize the VLA pointers */ + vla_ptr(vlabuf, d, stringtabs); + vla_ptr(vlabuf, d, stringtab); + vla_ptr(vlabuf, d, strings); + + stringtabs = d_stringtabs; + t = 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 = d_stringtabs; + t = d_stringtab; + s = d_strings; strings = s; } @@ -2208,16 +2231,15 @@ 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(d, struct ffs_ep, eps, ffs->eps_count); + vla_item(d, struct usb_descriptor_header *, fs_descs, + full ? ffs->fs_descs_count + 1 : 0); + vla_item(d, struct usb_descriptor_header *, hs_descs, + high ? ffs->hs_descs_count + 1 : 0); + vla_item(d, short, inums, ffs->interfaces_count); + vla_item(d, char, raw_descs, + high ? ffs->raw_descs_length : ffs->raw_fs_descs_length); ENTER(); @@ -2225,21 +2247,30 @@ if (unlikely(!(full | high))) return -ENOTSUPP; - /* Allocate */ - data = kmalloc(sizeof *data, GFP_KERNEL); - if (unlikely(!data)) + /* Allocate a single chunk, less management later on */ + char *vlabuf = kmalloc(vla_group_size(d), GFP_KERNEL); + if (unlikely(!vlabuf)) return -ENOMEM; + /* Initialize each struct member pointer in the allocated memory */ + vla_ptr(vlabuf, d, eps); + vla_ptr(vlabuf, d, fs_descs); + vla_ptr(vlabuf, d, hs_descs); + vla_ptr(vlabuf, d, inums); + vla_ptr(vlabuf, d, raw_descs); + /* 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(d_eps, 0, d_eps__sz); + memcpy(d_raw_descs, ffs->raw_descs + 16, d_raw_descs__sz); + memset(d_inums, 0xff, d_inums__sz); for (ret = ffs->eps_count; ret; --ret) - data->eps[ret].num = -1; + d_eps[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 = d_eps; + func->interfaces_nums = d_inums; /* * Go through all the endpoint descriptors and allocate @@ -2247,10 +2278,10 @@ * numbers without worrying that it may be described later on. */ if (likely(full)) { - func->function.fs_descriptors = data->fs_descs; + func->function.fs_descriptors = d_fs_descs; ret = ffs_do_descs(ffs->fs_descs_count, - data->raw_descs, - sizeof data->raw_descs, + d_raw_descs, + d_raw_descs__sz, __ffs_func_bind_do_descs, func); if (unlikely(ret < 0)) goto error; @@ -2259,10 +2290,10 @@ } if (likely(high)) { - func->function.hs_descriptors = data->hs_descs; + func->function.hs_descriptors = d_hs_descs; ret = ffs_do_descs(ffs->hs_descs_count, - data->raw_descs + ret, - (sizeof data->raw_descs) - ret, + d_raw_descs + ret, + d_raw_descs__sz - ret, __ffs_func_bind_do_descs, func); } @@ -2273,7 +2304,7 @@ */ ret = ffs_do_descs(ffs->fs_descs_count + (high ? ffs->hs_descs_count : 0), - data->raw_descs, sizeof data->raw_descs, + d_raw_descs, d_raw_descs__sz, __ffs_func_bind_do_nums, func); if (unlikely(ret < 0)) goto error; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/