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zram: use statically allocated compression algorithm names #598

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9 changes: 7 additions & 2 deletions drivers/block/zram/zcomp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
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2 changes: 1 addition & 1 deletion drivers/block/zram/zcomp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
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28 changes: 5 additions & 23 deletions drivers/block/zram/zram_drv.c
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Expand Up @@ -1637,43 +1637,29 @@ 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;
}

Expand Down Expand Up @@ -2851,12 +2837,8 @@ 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);
}
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