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zram: use statically allocated compression algorithm names

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Currently, zram dynamically allocates memory for compressor algorithm
names when they are set by the user.  This requires careful memory
management, including explicit `kfree` calls and special handling to avoid
freeing statically defined default compressor names.

This patch refactors the way zram handles compression algorithm names. 
Instead of storing dynamically allocated copies, `zram->comp_algs` will
now store pointers directly to the static name strings defined within the
`zcomp_ops` backend structures, thereby removing the need for conditional
`kfree` calls.

Link: https://lkml.kernel.org/r/5bb2e9318d124dbcb2b743dcdce6a950@honor.com
Signed-off-by: gao xu <gaoxu2@honor.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
gao xu
2026-02-26 12:37:22 +00:00
committed by Andrew Morton
parent 511f04aac4
commit c09fb53d29
3 changed files with 13 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/block/zram/zcomp.c
View File

@@ -84,9 +84,14 @@ static const struct zcomp_ops *lookup_backend_ops(const char *comp)
return backends[i];
}
bool zcomp_available_algorithm(const char *comp)
const char *zcomp_lookup_backend_name(const char *comp)
{
return lookup_backend_ops(comp) != NULL;
const struct zcomp_ops *backend = lookup_backend_ops(comp);
if (backend)
return backend->name;
return NULL;
}
/* show available compressors */

2
drivers/block/zram/zcomp.h
View File

@@ -80,7 +80,7 @@ struct zcomp {
int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node);
int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node);
ssize_t zcomp_available_show(const char *comp, char *buf, ssize_t at);
bool zcomp_available_algorithm(const char *comp);
const char *zcomp_lookup_backend_name(const char *comp);
struct zcomp *zcomp_create(const char *alg, struct zcomp_params *params);
void zcomp_destroy(struct zcomp *comp);

28
drivers/block/zram/zram_drv.c
View File

@@ -1621,43 +1621,29 @@ static void zram_debugfs_unregister(struct zram *zram) {};
static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg)
{
/* Do not free statically defined compression algorithms */
if (zram->comp_algs[prio] != default_compressor)
kfree(zram->comp_algs[prio]);
zram->comp_algs[prio] = alg;
}
static int __comp_algorithm_store(struct zram *zram, u32 prio, const char *buf)
{
char *compressor;
const char *alg;
size_t sz;
sz = strlen(buf);
if (sz >= ZRAM_MAX_ALGO_NAME_SZ)
return -E2BIG;
compressor = kstrdup(buf, GFP_KERNEL);
if (!compressor)
return -ENOMEM;
/* ignore trailing newline */
if (sz > 0 && compressor[sz - 1] == '\n')
compressor[sz - 1] = 0x00;
if (!zcomp_available_algorithm(compressor)) {
kfree(compressor);
alg = zcomp_lookup_backend_name(buf);
if (!alg)
return -EINVAL;
}
guard(rwsem_write)(&zram->dev_lock);
if (init_done(zram)) {
kfree(compressor);
pr_info("Can't change algorithm for initialized device\n");
return -EBUSY;
}
comp_algorithm_set(zram, prio, compressor);
comp_algorithm_set(zram, prio, alg);
return 0;
}
@@ -2840,12 +2826,8 @@ static void zram_destroy_comps(struct zram *zram)
zram->num_active_comps--;
}
for (prio = ZRAM_PRIMARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {
/* Do not free statically defined compression algorithms */
if (zram->comp_algs[prio] != default_compressor)
kfree(zram->comp_algs[prio]);
for (prio = ZRAM_PRIMARY_COMP; prio < ZRAM_MAX_COMPS; prio++)
zram->comp_algs[prio] = NULL;
}
zram_comp_params_reset(zram);
}