These patches change zswap to use charp type params instead of the
existing fixed length char[] buffers for the zpool and compressor params.
This saves memory and simplifies the param setting function.
Dan Streetman (2):
module: export param_free_charp()
zswap: use charp for zswap param strings
include/linux/moduleparam.h | 1 +
kernel/params.c | 3 +-
mm/zswap.c | 80 ++++++++++++++++++++++-----------------------
3 files changed, 43 insertions(+), 41 deletions(-)
--
2.1.0
Change the param_free_charp() function from static to exported.
It is used by zswap in the next patch.
Signed-off-by: Dan Streetman <[email protected]>
---
include/linux/moduleparam.h | 1 +
kernel/params.c | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index c12f214..52666d9 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -386,6 +386,7 @@ extern int param_get_ullong(char *buffer, const struct kernel_param *kp);
extern const struct kernel_param_ops param_ops_charp;
extern int param_set_charp(const char *val, const struct kernel_param *kp);
extern int param_get_charp(char *buffer, const struct kernel_param *kp);
+extern void param_free_charp(void *arg);
#define param_check_charp(name, p) __param_check(name, p, char *)
/* We used to allow int as well as bool. We're taking that away! */
diff --git a/kernel/params.c b/kernel/params.c
index b6554aa..93a380a 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -325,10 +325,11 @@ int param_get_charp(char *buffer, const struct kernel_param *kp)
}
EXPORT_SYMBOL(param_get_charp);
-static void param_free_charp(void *arg)
+void param_free_charp(void *arg)
{
maybe_kfree_parameter(*((char **)arg));
}
+EXPORT_SYMBOL(param_free_charp);
const struct kernel_param_ops param_ops_charp = {
.set = param_set_charp,
--
2.1.0
Instead of using a fixed-length string for the zswap params, use charp.
This simplifies the code and uses less memory, as most zswap param
strings will be less than the current maximum length.
Signed-off-by: Dan Streetman <[email protected]>
---
mm/zswap.c | 80 +++++++++++++++++++++++++++++++-------------------------------
1 file changed, 40 insertions(+), 40 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index 4043df7..3ff012f 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -82,33 +82,27 @@ module_param_named(enabled, zswap_enabled, bool, 0644);
/* Crypto compressor to use */
#define ZSWAP_COMPRESSOR_DEFAULT "lzo"
-static char zswap_compressor[CRYPTO_MAX_ALG_NAME] = ZSWAP_COMPRESSOR_DEFAULT;
-static struct kparam_string zswap_compressor_kparam = {
- .string = zswap_compressor,
- .maxlen = sizeof(zswap_compressor),
-};
+static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
static int zswap_compressor_param_set(const char *,
const struct kernel_param *);
static struct kernel_param_ops zswap_compressor_param_ops = {
.set = zswap_compressor_param_set,
- .get = param_get_string,
+ .get = param_get_charp,
+ .free = param_free_charp,
};
module_param_cb(compressor, &zswap_compressor_param_ops,
- &zswap_compressor_kparam, 0644);
+ &zswap_compressor, 0644);
/* Compressed storage zpool to use */
#define ZSWAP_ZPOOL_DEFAULT "zbud"
-static char zswap_zpool_type[32 /* arbitrary */] = ZSWAP_ZPOOL_DEFAULT;
-static struct kparam_string zswap_zpool_kparam = {
- .string = zswap_zpool_type,
- .maxlen = sizeof(zswap_zpool_type),
-};
+static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
static int zswap_zpool_param_set(const char *, const struct kernel_param *);
static struct kernel_param_ops zswap_zpool_param_ops = {
- .set = zswap_zpool_param_set,
- .get = param_get_string,
+ .set = zswap_zpool_param_set,
+ .get = param_get_charp,
+ .free = param_free_charp,
};
-module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_kparam, 0644);
+module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644);
/* The maximum percentage of memory that the compressed pool can occupy */
static unsigned int zswap_max_pool_percent = 20;
@@ -615,19 +609,29 @@ error:
return NULL;
}
-static struct zswap_pool *__zswap_pool_create_fallback(void)
+static __init struct zswap_pool *__zswap_pool_create_fallback(void)
{
if (!crypto_has_comp(zswap_compressor, 0, 0)) {
+ if (!strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) {
+ pr_err("default compressor %s not available\n",
+ zswap_compressor);
+ return NULL;
+ }
pr_err("compressor %s not available, using default %s\n",
zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT);
- strncpy(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT,
- sizeof(zswap_compressor));
+ param_free_charp(&zswap_compressor);
+ zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
}
if (!zpool_has_pool(zswap_zpool_type)) {
+ if (!strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
+ pr_err("default zpool %s not available\n",
+ zswap_zpool_type);
+ return NULL;
+ }
pr_err("zpool %s not available, using default %s\n",
zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT);
- strncpy(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT,
- sizeof(zswap_zpool_type));
+ param_free_charp(&zswap_zpool_type);
+ zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
}
return zswap_pool_create(zswap_zpool_type, zswap_compressor);
@@ -684,43 +688,39 @@ static void zswap_pool_put(struct zswap_pool *pool)
* param callbacks
**********************************/
+/* val must be a null-terminated string */
static int __zswap_param_set(const char *val, const struct kernel_param *kp,
char *type, char *compressor)
{
struct zswap_pool *pool, *put_pool = NULL;
- char str[kp->str->maxlen], *s;
+ char *s = strstrip((char *)val);
int ret;
- /*
- * kp is either zswap_zpool_kparam or zswap_compressor_kparam, defined
- * at the top of this file, so maxlen is CRYPTO_MAX_ALG_NAME (64) or
- * 32 (arbitrary).
- */
- strlcpy(str, val, kp->str->maxlen);
- s = strim(str);
+ /* no change required */
+ if (!strcmp(s, *(char **)kp->arg))
+ return 0;
/* if this is load-time (pre-init) param setting,
* don't create a pool; that's done during init.
*/
if (!zswap_init_started)
- return param_set_copystring(s, kp);
-
- /* no change required */
- if (!strncmp(kp->str->string, s, kp->str->maxlen))
- return 0;
+ return param_set_charp(s, kp);
if (!type) {
- type = s;
- if (!zpool_has_pool(type)) {
- pr_err("zpool %s not available\n", type);
+ if (!zpool_has_pool(s)) {
+ pr_err("zpool %s not available\n", s);
return -ENOENT;
}
+ type = s;
} else if (!compressor) {
- compressor = s;
- if (!crypto_has_comp(compressor, 0, 0)) {
- pr_err("compressor %s not available\n", compressor);
+ if (!crypto_has_comp(s, 0, 0)) {
+ pr_err("compressor %s not available\n", s);
return -ENOENT;
}
+ compressor = s;
+ } else {
+ WARN_ON(1);
+ return -EINVAL;
}
spin_lock(&zswap_pools_lock);
@@ -736,7 +736,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
}
if (pool)
- ret = param_set_copystring(s, kp);
+ ret = param_set_charp(s, kp);
else
ret = -EINVAL;
--
2.1.0
Dan Streetman <[email protected]> writes:
> Change the param_free_charp() function from static to exported.
>
> It is used by zswap in the next patch.
>
> Signed-off-by: Dan Streetman <[email protected]>
Acked-by: Rusty Russell <[email protected]>
Thanks!
Rusty.
> ---
> include/linux/moduleparam.h | 1 +
> kernel/params.c | 3 ++-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> index c12f214..52666d9 100644
> --- a/include/linux/moduleparam.h
> +++ b/include/linux/moduleparam.h
> @@ -386,6 +386,7 @@ extern int param_get_ullong(char *buffer, const struct kernel_param *kp);
> extern const struct kernel_param_ops param_ops_charp;
> extern int param_set_charp(const char *val, const struct kernel_param *kp);
> extern int param_get_charp(char *buffer, const struct kernel_param *kp);
> +extern void param_free_charp(void *arg);
> #define param_check_charp(name, p) __param_check(name, p, char *)
>
> /* We used to allow int as well as bool. We're taking that away! */
> diff --git a/kernel/params.c b/kernel/params.c
> index b6554aa..93a380a 100644
> --- a/kernel/params.c
> +++ b/kernel/params.c
> @@ -325,10 +325,11 @@ int param_get_charp(char *buffer, const struct kernel_param *kp)
> }
> EXPORT_SYMBOL(param_get_charp);
>
> -static void param_free_charp(void *arg)
> +void param_free_charp(void *arg)
> {
> maybe_kfree_parameter(*((char **)arg));
> }
> +EXPORT_SYMBOL(param_free_charp);
>
> const struct kernel_param_ops param_ops_charp = {
> .set = param_set_charp,
> --
> 2.1.0