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Date: Mon, 29 Mar 2021 17:20:18 -0400
From: Gabriel Krisman Bertazi <krisman@...labora.com>
To: Shreeya Patel <shreeya.patel@...labora.com>
Cc: tytso@....edu, adilger.kernel@...ger.ca, jaegeuk@...nel.org,
chao@...nel.org, ebiggers@...gle.com, drosen@...gle.com,
ebiggers@...nel.org, yuchao0@...wei.com,
linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net,
linux-fsdevel@...r.kernel.org, kernel@...labora.com,
andre.almeida@...labora.com
Subject: Re: [PATCH v5 4/4] fs: unicode: Add utf8 module and a unicode layer
Shreeya Patel <shreeya.patel@...labora.com> writes:
> utf8data.h_shipped has a large database table which is an auto-generated
> decodification trie for the unicode normalization functions.
> It is not necessary to load this large table in the kernel if no
> filesystem is using it, hence make UTF-8 encoding loadable by converting
> it into a module.
> Modify the file called unicode-core which will act as a layer for
> unicode subsystem. It will load the UTF-8 module and access it's functions
> whenever any filesystem that needs unicode is mounted.
> Also, indirect calls using function pointers are slow, use static calls to
> avoid overhead caused in case of repeated indirect calls. Static calls
> improves the performance by directly calling the functions as opposed to
> indirect calls.
>
> Signed-off-by: Shreeya Patel <shreeya.patel@...labora.com>
> ---
> Changes in v5
> - Rename global variables and default static call functions for better
> understanding
> - Make only config UNICODE_UTF8 visible and config UNICODE to be always
> enabled provided UNICODE_UTF8 is enabled.
> - Improve the documentation for Kconfig
> - Improve the commit message.
>
> Changes in v4
> - Return error from the static calls instead of doing nothing and
> succeeding even without loading the module.
> - Remove the complete usage of utf8_ops and use static calls at all
> places.
> - Restore the static calls to default values when module is unloaded.
> - Decrement the reference of module after calling the unload function.
> - Remove spinlock as there will be no race conditions after removing
> utf8_ops.
>
> Changes in v3
> - Add a patch which checks if utf8 is loaded before calling utf8_unload()
> in ext4 and f2fs filesystems
> - Return error if strscpy() returns value < 0
> - Correct the conditions to prevent NULL pointer dereference while
> accessing functions via utf8_ops variable.
> - Add spinlock to avoid race conditions.
> - Use static_call() for preventing speculative execution attacks.
>
> Changes in v2
> - Remove the duplicate file from the last patch.
> - Make the wrapper functions inline.
> - Remove msleep and use try_module_get() and module_put()
> for ensuring that module is loaded correctly and also
> doesn't get unloaded while in use.
> - Resolve the warning reported by kernel test robot.
> - Resolve all the checkpatch.pl warnings.
>
>
> fs/unicode/Kconfig | 17 ++-
> fs/unicode/Makefile | 5 +-
> fs/unicode/unicode-core.c | 241 +++++++----------------------------
> fs/unicode/unicode-utf8.c | 256 ++++++++++++++++++++++++++++++++++++++
> include/linux/unicode.h | 123 +++++++++++++++---
> 5 files changed, 426 insertions(+), 216 deletions(-)
> create mode 100644 fs/unicode/unicode-utf8.c
>
> diff --git a/fs/unicode/Kconfig b/fs/unicode/Kconfig
> index 2c27b9a5cd6c..ad4b837f2eb2 100644
> --- a/fs/unicode/Kconfig
> +++ b/fs/unicode/Kconfig
> @@ -2,13 +2,26 @@
> #
> # UTF-8 normalization
> #
> +# CONFIG_UNICODE will be automatically enabled if CONFIG_UNICODE_UTF8
> +# is enabled. This config option adds the unicode subsystem layer which loads
> +# the UTF-8 module whenever any filesystem needs it.
> config UNICODE
> - bool "UTF-8 normalization and casefolding support"
> + bool
> +
> +# utf8data.h_shipped has a large database table which is an auto-generated
> +# decodification trie for the unicode normalization functions and it is not
> +# necessary to carry this large table in the kernel.
> +# Enabling UNICODE_UTF8 option will allow UTF-8 encoding to be built as a
> +# module and this module will be loaded by the unicode subsystem layer only
> +# when any filesystem needs it.
> +config UNICODE_UTF8
> + tristate "UTF-8 module"
> help
> Say Y here to enable UTF-8 NFD normalization and NFD+CF casefolding
> support.
> + select UNICODE
>
> config UNICODE_NORMALIZATION_SELFTEST
> tristate "Test UTF-8 normalization support"
> - depends on UNICODE
> + depends on UNICODE_UTF8
> default n
> diff --git a/fs/unicode/Makefile b/fs/unicode/Makefile
> index fbf9a629ed0d..49d50083e6ee 100644
> --- a/fs/unicode/Makefile
> +++ b/fs/unicode/Makefile
> @@ -1,11 +1,14 @@
> # SPDX-License-Identifier: GPL-2.0
>
> obj-$(CONFIG_UNICODE) += unicode.o
> +obj-$(CONFIG_UNICODE_UTF8) += utf8.o
> obj-$(CONFIG_UNICODE_NORMALIZATION_SELFTEST) += utf8-selftest.o
>
> -unicode-y := utf8-norm.o unicode-core.o
> +unicode-y := unicode-core.o
> +utf8-y := unicode-utf8.o utf8-norm.o
>
> $(obj)/utf8-norm.o: $(obj)/utf8data.h
> +$(obj)/unicode-utf8.o: $(obj)/utf8-norm.o
>
> # In the normal build, the checked-in utf8data.h is just shipped.
> #
> diff --git a/fs/unicode/unicode-core.c b/fs/unicode/unicode-core.c
> index 730dbaedf593..07d42f471e42 100644
> --- a/fs/unicode/unicode-core.c
> +++ b/fs/unicode/unicode-core.c
> @@ -1,237 +1,80 @@
> /* SPDX-License-Identifier: GPL-2.0 */
> #include <linux/module.h>
> #include <linux/kernel.h>
> -#include <linux/string.h>
> #include <linux/slab.h>
> -#include <linux/parser.h>
> #include <linux/errno.h>
> #include <linux/unicode.h>
> -#include <linux/stringhash.h>
>
> -#include "utf8n.h"
> +static struct module *utf8mod;
>
> -int unicode_validate(const struct unicode_map *um, const struct qstr *str)
> -{
> - const struct utf8data *data = utf8nfdi(um->version);
> +DEFINE_STATIC_CALL(_unicode_validate, unicode_validate_default);
> +EXPORT_STATIC_CALL(_unicode_validate);
>
> - if (utf8nlen(data, str->name, str->len) < 0)
> - return -1;
> - return 0;
> -}
> -EXPORT_SYMBOL(unicode_validate);
> +DEFINE_STATIC_CALL(_unicode_strncmp, unicode_strncmp_default);
> +EXPORT_STATIC_CALL(_unicode_strncmp);
>
> -int unicode_strncmp(const struct unicode_map *um,
> - const struct qstr *s1, const struct qstr *s2)
> -{
> - const struct utf8data *data = utf8nfdi(um->version);
> - struct utf8cursor cur1, cur2;
> - int c1, c2;
> +DEFINE_STATIC_CALL(_unicode_strncasecmp, unicode_strncasecmp_default);
> +EXPORT_STATIC_CALL(_unicode_strncasecmp);
Why are these here if the _default functions are defined in the header
file? I think the definitions could be in this file. No?
> - if (utf8ncursor(&cur1, data, s1->name, s1->len) < 0)
> - return -EINVAL;
> +DEFINE_STATIC_CALL(_unicode_strncasecmp_folded, unicode_strncasecmp_folded_default);
> +EXPORT_STATIC_CALL(_unicode_strncasecmp_folded);
>
> - if (utf8ncursor(&cur2, data, s2->name, s2->len) < 0)
> - return -EINVAL;
> +DEFINE_STATIC_CALL(_unicode_normalize, unicode_normalize_default);
> +EXPORT_STATIC_CALL(_unicode_normalize);
>
> - do {
> - c1 = utf8byte(&cur1);
> - c2 = utf8byte(&cur2);
> +DEFINE_STATIC_CALL(_unicode_casefold, unicode_casefold_default);
> +EXPORT_STATIC_CALL(_unicode_casefold);
>
> - if (c1 < 0 || c2 < 0)
> - return -EINVAL;
> - if (c1 != c2)
> - return 1;
> - } while (c1);
> +DEFINE_STATIC_CALL(_unicode_casefold_hash, unicode_casefold_hash_default);
> +EXPORT_STATIC_CALL(_unicode_casefold_hash);
>
> - return 0;
> -}
> -EXPORT_SYMBOL(unicode_strncmp);
> +DEFINE_STATIC_CALL(_unicode_load, unicode_load_default);
> +EXPORT_STATIC_CALL(_unicode_load);
>
> -int unicode_strncasecmp(const struct unicode_map *um,
> - const struct qstr *s1, const struct qstr *s2)
> +static int unicode_load_module(void)
> {
> - const struct utf8data *data = utf8nfdicf(um->version);
> - struct utf8cursor cur1, cur2;
> - int c1, c2;
> -
> - if (utf8ncursor(&cur1, data, s1->name, s1->len) < 0)
> - return -EINVAL;
> -
> - if (utf8ncursor(&cur2, data, s2->name, s2->len) < 0)
> - return -EINVAL;
> -
> - do {
> - c1 = utf8byte(&cur1);
> - c2 = utf8byte(&cur2);
> -
> - if (c1 < 0 || c2 < 0)
> - return -EINVAL;
> - if (c1 != c2)
> - return 1;
> - } while (c1);
> -
> - return 0;
> -}
> -EXPORT_SYMBOL(unicode_strncasecmp);
> -
> -/* String cf is expected to be a valid UTF-8 casefolded
> - * string.
> - */
> -int unicode_strncasecmp_folded(const struct unicode_map *um,
> - const struct qstr *cf,
> - const struct qstr *s1)
> -{
> - const struct utf8data *data = utf8nfdicf(um->version);
> - struct utf8cursor cur1;
> - int c1, c2;
> - int i = 0;
> -
> - if (utf8ncursor(&cur1, data, s1->name, s1->len) < 0)
> - return -EINVAL;
> -
> - do {
> - c1 = utf8byte(&cur1);
> - c2 = cf->name[i++];
> - if (c1 < 0)
> - return -EINVAL;
> - if (c1 != c2)
> - return 1;
> - } while (c1);
> -
> - return 0;
> -}
> -EXPORT_SYMBOL(unicode_strncasecmp_folded);
> -
> -int unicode_casefold(const struct unicode_map *um, const struct qstr *str,
> - unsigned char *dest, size_t dlen)
> -{
> - const struct utf8data *data = utf8nfdicf(um->version);
> - struct utf8cursor cur;
> - size_t nlen = 0;
> -
> - if (utf8ncursor(&cur, data, str->name, str->len) < 0)
> - return -EINVAL;
> -
> - for (nlen = 0; nlen < dlen; nlen++) {
> - int c = utf8byte(&cur);
> -
> - dest[nlen] = c;
> - if (!c)
> - return nlen;
> - if (c == -1)
> - break;
> - }
> - return -EINVAL;
> -}
> -EXPORT_SYMBOL(unicode_casefold);
> + int ret = request_module("utf8");
>
> -int unicode_casefold_hash(const struct unicode_map *um, const void *salt,
> - struct qstr *str)
> -{
> - const struct utf8data *data = utf8nfdicf(um->version);
> - struct utf8cursor cur;
> - int c;
> - unsigned long hash = init_name_hash(salt);
> -
> - if (utf8ncursor(&cur, data, str->name, str->len) < 0)
> - return -EINVAL;
> -
> - while ((c = utf8byte(&cur))) {
> - if (c < 0)
> - return -EINVAL;
> - hash = partial_name_hash((unsigned char)c, hash);
> + if (ret) {
> + pr_err("Failed to load UTF-8 module\n");
> + return ret;
> }
> - str->hash = end_name_hash(hash);
> return 0;
> }
> -EXPORT_SYMBOL(unicode_casefold_hash);
>
> -int unicode_normalize(const struct unicode_map *um, const struct qstr *str,
> - unsigned char *dest, size_t dlen)
> +struct unicode_map *unicode_load(const char *version)
> {
> - const struct utf8data *data = utf8nfdi(um->version);
> - struct utf8cursor cur;
> - ssize_t nlen = 0;
> -
> - if (utf8ncursor(&cur, data, str->name, str->len) < 0)
> - return -EINVAL;
> + int ret = unicode_load_module();
Splitting this in two functions sound unnecessary, since the other
function just calls request_module. By the way, is there any protection
against calling request_module if the module is already loaded? Surely
that's not necessary, perhaps try_then_request_module(utf8mod, "utf8")?
> - for (nlen = 0; nlen < dlen; nlen++) {
> - int c = utf8byte(&cur);
> + if (ret)
> + return ERR_PTR(ret);
>
> - dest[nlen] = c;
> - if (!c)
> - return nlen;
> - if (c == -1)
> - break;
> - }
> - return -EINVAL;
> + if (!try_module_get(utf8mod))
Can't module_unregister be called in between the register_module and
here, and then you have a bogus utf8mod pointer? true, try_module_get
checks for NULL, but if you are unlucky module_is_live will it breaks.
I still think utf8mod needs to be protected while you don't have a
reference to the module.
> + return ERR_PTR(-ENODEV);
> + else
> + return static_call(_unicode_load)(version);
> }
> -EXPORT_SYMBOL(unicode_normalize);
> +EXPORT_SYMBOL(unicode_load);
>
> -static int unicode_parse_version(const char *version, unsigned int *maj,
> - unsigned int *min, unsigned int *rev)
> +void unicode_unload(struct unicode_map *um)
> {
> - substring_t args[3];
> - char version_string[12];
> - static const struct match_token token[] = {
> - {1, "%d.%d.%d"},
> - {0, NULL}
> - };
> - int ret = strscpy(version_string, version, sizeof(version_string));
> -
> - if (ret < 0)
> - return ret;
> -
> - if (match_token(version_string, token, args) != 1)
> - return -EINVAL;
> -
> - if (match_int(&args[0], maj) || match_int(&args[1], min) ||
> - match_int(&args[2], rev))
> - return -EINVAL;
> + kfree(um);
>
> - return 0;
> + if (utf8mod)
> + module_put(utf8mod);
> }
> +EXPORT_SYMBOL(unicode_unload);
>
> -struct unicode_map *unicode_load(const char *version)
> +void unicode_register(struct module *owner)
> {
> - struct unicode_map *um = NULL;
> - int unicode_version;
> -
> - if (version) {
> - unsigned int maj, min, rev;
> -
> - if (unicode_parse_version(version, &maj, &min, &rev) < 0)
> - return ERR_PTR(-EINVAL);
> -
> - if (!utf8version_is_supported(maj, min, rev))
> - return ERR_PTR(-EINVAL);
> -
> - unicode_version = UNICODE_AGE(maj, min, rev);
> - } else {
> - unicode_version = utf8version_latest();
> - printk(KERN_WARNING"UTF-8 version not specified. "
> - "Assuming latest supported version (%d.%d.%d).",
> - (unicode_version >> 16) & 0xff,
> - (unicode_version >> 8) & 0xff,
> - (unicode_version & 0xff));
> - }
> -
> - um = kzalloc(sizeof(struct unicode_map), GFP_KERNEL);
> - if (!um)
> - return ERR_PTR(-ENOMEM);
> -
> - um->charset = "UTF-8";
> - um->version = unicode_version;
> -
> - return um;
> + utf8mod = owner;
> }
> -EXPORT_SYMBOL(unicode_load);
> +EXPORT_SYMBOL(unicode_register);
>
> -void unicode_unload(struct unicode_map *um)
> +void unicode_unregister(void)
> {
> - kfree(um);
> + utf8mod = NULL;
> }
> -EXPORT_SYMBOL(unicode_unload);
> +EXPORT_SYMBOL(unicode_unregister);
>
> MODULE_LICENSE("GPL v2");
> diff --git a/fs/unicode/unicode-utf8.c b/fs/unicode/unicode-utf8.c
> new file mode 100644
> index 000000000000..9c6b58239067
> --- /dev/null
> +++ b/fs/unicode/unicode-utf8.c
> @@ -0,0 +1,256 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/string.h>
> +#include <linux/slab.h>
> +#include <linux/parser.h>
> +#include <linux/errno.h>
> +#include <linux/unicode.h>
> +#include <linux/stringhash.h>
> +#include <linux/static_call.h>
> +
> +#include "utf8n.h"
> +
> +static int utf8_validate(const struct unicode_map *um, const struct qstr *str)
> +{
> + const struct utf8data *data = utf8nfdi(um->version);
> +
> + if (utf8nlen(data, str->name, str->len) < 0)
> + return -1;
> + return 0;
> +}
> +
> +static int utf8_strncmp(const struct unicode_map *um,
> + const struct qstr *s1, const struct qstr *s2)
> +{
> + const struct utf8data *data = utf8nfdi(um->version);
> + struct utf8cursor cur1, cur2;
> + int c1, c2;
> +
> + if (utf8ncursor(&cur1, data, s1->name, s1->len) < 0)
> + return -EINVAL;
> +
> + if (utf8ncursor(&cur2, data, s2->name, s2->len) < 0)
> + return -EINVAL;
> +
> + do {
> + c1 = utf8byte(&cur1);
> + c2 = utf8byte(&cur2);
> +
> + if (c1 < 0 || c2 < 0)
> + return -EINVAL;
> + if (c1 != c2)
> + return 1;
> + } while (c1);
> +
> + return 0;
> +}
> +
> +static int utf8_strncasecmp(const struct unicode_map *um,
> + const struct qstr *s1, const struct qstr *s2)
> +{
> + const struct utf8data *data = utf8nfdicf(um->version);
> + struct utf8cursor cur1, cur2;
> + int c1, c2;
> +
> + if (utf8ncursor(&cur1, data, s1->name, s1->len) < 0)
> + return -EINVAL;
> +
> + if (utf8ncursor(&cur2, data, s2->name, s2->len) < 0)
> + return -EINVAL;
> +
> + do {
> + c1 = utf8byte(&cur1);
> + c2 = utf8byte(&cur2);
> +
> + if (c1 < 0 || c2 < 0)
> + return -EINVAL;
> + if (c1 != c2)
> + return 1;
> + } while (c1);
> +
> + return 0;
> +}
> +
> +/* String cf is expected to be a valid UTF-8 casefolded
> + * string.
> + */
> +static int utf8_strncasecmp_folded(const struct unicode_map *um,
> + const struct qstr *cf,
> + const struct qstr *s1)
> +{
> + const struct utf8data *data = utf8nfdicf(um->version);
> + struct utf8cursor cur1;
> + int c1, c2;
> + int i = 0;
> +
> + if (utf8ncursor(&cur1, data, s1->name, s1->len) < 0)
> + return -EINVAL;
> +
> + do {
> + c1 = utf8byte(&cur1);
> + c2 = cf->name[i++];
> + if (c1 < 0)
> + return -EINVAL;
> + if (c1 != c2)
> + return 1;
> + } while (c1);
> +
> + return 0;
> +}
> +
> +static int utf8_casefold(const struct unicode_map *um, const struct qstr *str,
> + unsigned char *dest, size_t dlen)
> +{
> + const struct utf8data *data = utf8nfdicf(um->version);
> + struct utf8cursor cur;
> + size_t nlen = 0;
> +
> + if (utf8ncursor(&cur, data, str->name, str->len) < 0)
> + return -EINVAL;
> +
> + for (nlen = 0; nlen < dlen; nlen++) {
> + int c = utf8byte(&cur);
> +
> + dest[nlen] = c;
> + if (!c)
> + return nlen;
> + if (c == -1)
> + break;
> + }
> + return -EINVAL;
> +}
> +
> +static int utf8_casefold_hash(const struct unicode_map *um, const void *salt,
> + struct qstr *str)
> +{
> + const struct utf8data *data = utf8nfdicf(um->version);
> + struct utf8cursor cur;
> + int c;
> + unsigned long hash = init_name_hash(salt);
> +
> + if (utf8ncursor(&cur, data, str->name, str->len) < 0)
> + return -EINVAL;
> +
> + while ((c = utf8byte(&cur))) {
> + if (c < 0)
> + return -EINVAL;
> + hash = partial_name_hash((unsigned char)c, hash);
> + }
> + str->hash = end_name_hash(hash);
> + return 0;
> +}
> +
> +static int utf8_normalize(const struct unicode_map *um, const struct qstr *str,
> + unsigned char *dest, size_t dlen)
> +{
> + const struct utf8data *data = utf8nfdi(um->version);
> + struct utf8cursor cur;
> + ssize_t nlen = 0;
> +
> + if (utf8ncursor(&cur, data, str->name, str->len) < 0)
> + return -EINVAL;
> +
> + for (nlen = 0; nlen < dlen; nlen++) {
> + int c = utf8byte(&cur);
> +
> + dest[nlen] = c;
> + if (!c)
> + return nlen;
> + if (c == -1)
> + break;
> + }
> + return -EINVAL;
> +}
> +
> +static int utf8_parse_version(const char *version, unsigned int *maj,
> + unsigned int *min, unsigned int *rev)
> +{
> + substring_t args[3];
> + char version_string[12];
> + static const struct match_token token[] = {
> + {1, "%d.%d.%d"},
> + {0, NULL}
> + };
> +
> + int ret = strscpy(version_string, version, sizeof(version_string));
> +
> + if (ret < 0)
> + return ret;
> +
> + if (match_token(version_string, token, args) != 1)
> + return -EINVAL;
> +
> + if (match_int(&args[0], maj) || match_int(&args[1], min) ||
> + match_int(&args[2], rev))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static struct unicode_map *utf8_load(const char *version)
> +{
> + struct unicode_map *um = NULL;
> + int unicode_version;
> +
> + if (version) {
> + unsigned int maj, min, rev;
> +
> + if (utf8_parse_version(version, &maj, &min, &rev) < 0)
> + return ERR_PTR(-EINVAL);
> +
> + if (!utf8version_is_supported(maj, min, rev))
> + return ERR_PTR(-EINVAL);
> +
> + unicode_version = UNICODE_AGE(maj, min, rev);
> + } else {
> + unicode_version = utf8version_latest();
> + pr_warn("UTF-8 version not specified. Assuming latest supported version (%d.%d.%d).",
> + (unicode_version >> 16) & 0xff,
> + (unicode_version >> 8) & 0xff,
> + (unicode_version & 0xfe));
> + }
> +
> + um = kzalloc(sizeof(*um), GFP_KERNEL);
> + if (!um)
> + return ERR_PTR(-ENOMEM);
> +
> + um->charset = "UTF-8";
> + um->version = unicode_version;
> +
> + return um;
> +}
> +
> +static int __init utf8_init(void)
> +{
> + static_call_update(_unicode_validate, utf8_validate);
> + static_call_update(_unicode_strncmp, utf8_strncmp);
> + static_call_update(_unicode_strncasecmp, utf8_strncasecmp);
> + static_call_update(_unicode_strncasecmp_folded, utf8_strncasecmp_folded);
> + static_call_update(_unicode_normalize, utf8_normalize);
> + static_call_update(_unicode_casefold, utf8_casefold);
> + static_call_update(_unicode_casefold_hash, utf8_casefold_hash);
> + static_call_update(_unicode_load, utf8_load);
> +
> + unicode_register(THIS_MODULE);
> + return 0;
> +}
> +
> +static void __exit utf8_exit(void)
> +{
> + static_call_update(_unicode_validate, unicode_validate_default);
> + static_call_update(_unicode_strncmp, unicode_strncmp_default);
> + static_call_update(_unicode_strncasecmp, unicode_strncasecmp_default);
> + static_call_update(_unicode_strncasecmp_folded, unicode_strncasecmp_folded_default);
> + static_call_update(_unicode_normalize, unicode_normalize_default);
> + static_call_update(_unicode_casefold, unicode_casefold_default);
> + static_call_update(_unicode_casefold_hash, unicode_casefold_hash_default);
> + static_call_update(_unicode_load, unicode_load_default);
> +
> + unicode_unregister();
> +}
> +
> +module_init(utf8_init);
> +module_exit(utf8_exit);
> +
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/unicode.h b/include/linux/unicode.h
> index de23f9ee720b..18a1d3db9de5 100644
> --- a/include/linux/unicode.h
> +++ b/include/linux/unicode.h
> @@ -4,33 +4,128 @@
>
> #include <linux/init.h>
> #include <linux/dcache.h>
> +#include <linux/static_call.h>
> +
>
> struct unicode_map {
> const char *charset;
> int version;
> };
>
> -int unicode_validate(const struct unicode_map *um, const struct qstr *str);
> +static int unicode_warn_on(void)
> +{
> + WARN_ON(1);
> + return -EIO;
> +}
Creating this extra function adds the same number of lines than if you
write `WARN_ON(1); return -EIO;` in each of the few handlers below, but
the later would be more clear, and you already do it for
unicode_load_default anyway. :)
> +
> +static int unicode_validate_default(const struct unicode_map *um,
> + const struct qstr *str)
> +{
> + return unicode_warn_on();
> +}
> +
> +static int unicode_strncmp_default(const struct unicode_map *um,
> + const struct qstr *s1,
> + const struct qstr *s2)
> +{
> + return unicode_warn_on();
> +}
> +
> +static int unicode_strncasecmp_default(const struct unicode_map *um,
> + const struct qstr *s1,
> + const struct qstr *s2)
> +{
> + return unicode_warn_on();
> +}
> +
> +static int unicode_strncasecmp_folded_default(const struct unicode_map *um,
> + const struct qstr *cf,
> + const struct qstr *s1)
> +{
> + return unicode_warn_on();
> +}
> +
> +static int unicode_normalize_default(const struct unicode_map *um,
> + const struct qstr *str,
> + unsigned char *dest, size_t dlen)
> +{
> + return unicode_warn_on();
> +}
> +
> +static int unicode_casefold_default(const struct unicode_map *um,
> + const struct qstr *str,
> + unsigned char *dest, size_t dlen)
> +{
> + return unicode_warn_on();
> +}
>
> -int unicode_strncmp(const struct unicode_map *um,
> - const struct qstr *s1, const struct qstr *s2);
> +static int unicode_casefold_hash_default(const struct unicode_map *um,
> + const void *salt, struct qstr *str)
> +{
> + return unicode_warn_on();
> +}
Again, why isn't this in a .c ? Does it need to be here?
>
> -int unicode_strncasecmp(const struct unicode_map *um,
> - const struct qstr *s1, const struct qstr *s2);
> -int unicode_strncasecmp_folded(const struct unicode_map *um,
> - const struct qstr *cf,
> - const struct qstr *s1);
> +static struct unicode_map *unicode_load_default(const char *version)
> +{
> + unicode_warn_on();
> + return ERR_PTR(-EIO);
> +}
>
> -int unicode_normalize(const struct unicode_map *um, const struct qstr *str,
> - unsigned char *dest, size_t dlen);
> +DECLARE_STATIC_CALL(_unicode_validate, unicode_validate_default);
> +DECLARE_STATIC_CALL(_unicode_strncmp, unicode_strncmp_default);
> +DECLARE_STATIC_CALL(_unicode_strncasecmp, unicode_strncasecmp_default);
> +DECLARE_STATIC_CALL(_unicode_strncasecmp_folded, unicode_strncasecmp_folded_default);
> +DECLARE_STATIC_CALL(_unicode_normalize, unicode_normalize_default);
> +DECLARE_STATIC_CALL(_unicode_casefold, unicode_casefold_default);
> +DECLARE_STATIC_CALL(_unicode_casefold_hash, unicode_casefold_hash_default);
> +DECLARE_STATIC_CALL(_unicode_load, unicode_load_default);
nit: I hate this functions starting with a single _ . they are not common in the
rest of the kernel either.
> -int unicode_casefold(const struct unicode_map *um, const struct qstr *str,
> - unsigned char *dest, size_t dlen);
> +static inline int unicode_validate(const struct unicode_map *um, const struct qstr *str)
> +{
> + return static_call(_unicode_validate)(um, str);
> +}
>
> -int unicode_casefold_hash(const struct unicode_map *um, const void *salt,
> - struct qstr *str);
> +static inline int unicode_strncmp(const struct unicode_map *um,
> + const struct qstr *s1, const struct qstr *s2)
> +{
> + return static_call(_unicode_strncmp)(um, s1, s2);
> +}
> +
> +static inline int unicode_strncasecmp(const struct unicode_map *um,
> + const struct qstr *s1, const struct qstr *s2)
> +{
> + return static_call(_unicode_strncasecmp)(um, s1, s2);
> +}
> +
> +static inline int unicode_strncasecmp_folded(const struct unicode_map *um,
> + const struct qstr *cf,
> + const struct qstr *s1)
> +{
> + return static_call(_unicode_strncasecmp_folded)(um, cf, s1);
> +}
> +
> +static inline int unicode_normalize(const struct unicode_map *um, const struct qstr *str,
> + unsigned char *dest, size_t dlen)
> +{
> + return static_call(_unicode_normalize)(um, str, dest, dlen);
> +}
> +
> +static inline int unicode_casefold(const struct unicode_map *um, const struct qstr *str,
> + unsigned char *dest, size_t dlen)
> +{
> + return static_call(_unicode_casefold)(um, str, dest, dlen);
> +}
> +
> +static inline int unicode_casefold_hash(const struct unicode_map *um, const void *salt,
> + struct qstr *str)
> +{
> + return static_call(_unicode_casefold_hash)(um, salt, str);
> +}
>
> struct unicode_map *unicode_load(const char *version);
> void unicode_unload(struct unicode_map *um);
>
> +void unicode_register(struct module *owner);
> +void unicode_unregister(void);
> +
> #endif /* _LINUX_UNICODE_H */
--
Gabriel Krisman Bertazi
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