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Threaded depmod, take 2 #425

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31aa4c8
tools/depmod: return error on array_append failure
evelikov Feb 12, 2026
42c6708
tools/depmod: split depmod_symbol_{create,add}
evelikov Feb 12, 2026
179b6c0
tools/depmod: factor out module symbol resolution
evelikov Feb 12, 2026
f65443f
tools/depmod: Parallelize module loading
evelikov Feb 13, 2026
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73 changes: 50 additions & 23 deletions tools/depmod.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1548,11 +1548,11 @@ static void depmod_modules_sort(struct depmod *depmod)
fclose(fp);
}

static int depmod_symbol_add(struct depmod *depmod, const char *name, bool prefix_skipped,
uint64_t crc, const struct mod *owner)
static struct symbol *depmod_symbol_create(struct depmod *depmod, const char *name,
bool prefix_skipped, uint64_t crc,
const struct mod *owner)
{
size_t namelen;
int err;
struct symbol *sym;

if (!prefix_skipped && (name[0] == depmod->cfg->sym_prefix))
Expand All @@ -1561,20 +1561,22 @@ static int depmod_symbol_add(struct depmod *depmod, const char *name, bool prefi
namelen = strlen(name) + 1;
sym = malloc(sizeof(struct symbol) + namelen);
if (sym == NULL)
return -ENOMEM;
return NULL;

sym->owner = (struct mod *)owner;
sym->crc = crc;
memcpy(sym->name, name, namelen);
return sym;
}

err = hash_add(depmod->symbols, sym->name, sym);
if (err < 0) {
free(sym);
static int depmod_symbol_add(struct depmod *depmod, struct symbol *sym)
{
int err = hash_add(depmod->symbols, sym->name, sym);
if (err < 0)

@lucasdemarchi lucasdemarchi May 7, 2026

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should we keep the free(sym) here to avoid leaking it?

@evelikov evelikov May 31, 2026

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The commit introducing the split tries to highlight that we have a (somewhat) serious issue with missing error handling - admittedly this isn't making it better. A free here, seems to mess up with the ownership model IMHO.

Perhaps the better options is to use the split API only as needed and have a wrapper (depmod_symbol_create_n_add?) for the rest - preserving the current state.

return err;
}

DBG("add %p sym=%s, owner=%p %s\n", sym, sym->name, owner,
owner != NULL ? owner->path : "");
DBG("add %p sym=%s, owner=%p %s\n", sym, sym->name, sym->owner,
sym->owner != NULL ? sym->owner->path : "");

return 0;
}
Expand Down Expand Up @@ -1611,7 +1613,11 @@ static int depmod_load_modules(struct depmod *depmod)
kmod_list_foreach(l, list) {
const char *name = kmod_module_symbol_get_symbol(l);
uint64_t crc = kmod_module_symbol_get_crc(l);
depmod_symbol_add(depmod, name, false, crc, mod);
struct symbol *sym;

sym = depmod_symbol_create(depmod, name, false, crc, mod);
if (sym)
depmod_symbol_add(depmod, sym);
}
kmod_module_symbols_free_list(list);

Expand All @@ -1623,22 +1629,25 @@ static int depmod_load_modules(struct depmod *depmod)
if (streq(key, "alias")) {
const char *value = kmod_module_info_get_value(l);

if (array_append(&mod->alias_values, value) < 0)
return 0;
err = array_append(&mod->alias_values, value);
if (err < 0)
return err;
continue;
}
if (streq(key, "softdep")) {
const char *value = kmod_module_info_get_value(l);

if (array_append(&mod->softdep_values, value) < 0)
return 0;
err = array_append(&mod->softdep_values, value);
if (err < 0)
return err;
continue;
}
if (streq(key, "weakdep")) {
const char *value = kmod_module_info_get_value(l);

if (array_append(&mod->weakdep_values, value) < 0)
return 0;
err = array_append(&mod->weakdep_values, value);
if (err < 0)
return err;
continue;
}
}
Expand Down Expand Up @@ -2642,13 +2651,24 @@ static int depmod_output(struct depmod *depmod, FILE *out)

static void depmod_add_fake_syms(struct depmod *depmod)
{
struct symbol *sym;

/* __this_module is magically inserted by kernel loader. */
depmod_symbol_add(depmod, "__this_module", true, 0, NULL);
sym = depmod_symbol_create(depmod, "__this_module", true, 0, NULL);
if (sym)
depmod_symbol_add(depmod, sym);

/* On S390, this is faked up too */
depmod_symbol_add(depmod, "_GLOBAL_OFFSET_TABLE_", true, 0, NULL);
sym = depmod_symbol_create(depmod, "_GLOBAL_OFFSET_TABLE_", true, 0, NULL);
if (sym)
depmod_symbol_add(depmod, sym);

/* On PowerPC64 ABIv2, .TOC. is more or less _GLOBAL_OFFSET_TABLE_ */
if (!depmod_symbol_find(depmod, "TOC."))
depmod_symbol_add(depmod, "TOC.", true, 0, NULL);
if (!depmod_symbol_find(depmod, "TOC.")) {
sym = depmod_symbol_create(depmod, "TOC.", true, 0, NULL);
if (sym)
depmod_symbol_add(depmod, sym);
}
}

static int depmod_load_symvers(struct depmod *depmod, const char *filename)
Expand All @@ -2667,6 +2687,7 @@ static int depmod_load_symvers(struct depmod *depmod, const char *filename)

/* eg. "0xb352177e\tfind_first_bit\tvmlinux\tEXPORT_SYMBOL" */
while (fgets(line, sizeof(line), fp) != NULL) {
struct symbol *symbol;
const char *ver, *sym, *where;
char *verend;
uint64_t crc;
Expand All @@ -2690,7 +2711,9 @@ static int depmod_load_symvers(struct depmod *depmod, const char *filename)
continue;
}

depmod_symbol_add(depmod, sym, false, crc, NULL);
symbol = depmod_symbol_create(depmod, sym, false, crc, NULL);
if (symbol)
depmod_symbol_add(depmod, symbol);
}
depmod_add_fake_syms(depmod);

Expand Down Expand Up @@ -2718,6 +2741,7 @@ static int depmod_load_system_map(struct depmod *depmod, const char *filename)

/* eg. c0294200 R __ksymtab_devfs_alloc_devnum */
while (fgets(line, sizeof(line), fp) != NULL) {
struct symbol *sym;
char *p, *end;

linenum++;
Expand All @@ -2743,7 +2767,10 @@ static int depmod_load_system_map(struct depmod *depmod, const char *filename)
if (end != NULL)
*end = '\0';

depmod_symbol_add(depmod, p + ksymstr_len, true, 0, NULL);
sym = depmod_symbol_create(depmod, p + ksymstr_len, true, 0, NULL);
if (sym)
depmod_symbol_add(depmod, sym);

continue;

invalid_syntax:
Expand Down