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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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3 changes: 3 additions & 0 deletions meson.build
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Original file line number Diff line number Diff line change
Expand Up @@ -444,10 +444,13 @@ if get_option('tools')
'tools/static-nodes.c',
)

pthread_dep = dependency('threads', required : true)

kmod = executable(
'kmod',
kmod_sources,
link_with : [libshared, libkmod_internal],
dependencies : pthread_dep,
gnu_symbol_visibility : 'hidden',
install : true,
)
Expand Down
190 changes: 160 additions & 30 deletions tools/depmod.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include <errno.h>
#include <getopt.h>
#include <limits.h>
#include <pthread.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
Expand Down Expand Up @@ -1548,11 +1549,11 @@
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 +1562,22 @@
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)
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 All @@ -1588,16 +1591,21 @@
return hash_find(depmod->symbols, name);
}

static int depmod_load_modules(struct depmod *depmod)
struct module_symbols {
struct depmod *depmod;
struct mod **modules;
size_t modules_count;
struct array symbols; /* struct symbol */
};

static void *resolve_module_symbols(void *arg)
{
struct mod **itr, **itr_end;
struct module_symbols *mod_syms = arg;

DBG("load symbols (%zu modules)\n", depmod->modules.count);
array_init(&mod_syms->symbols, 128);

itr = (struct mod **)depmod->modules.array;
itr_end = itr + depmod->modules.count;
for (; itr < itr_end; itr++) {
struct mod *mod = *itr;
for (size_t i = 0; i < mod_syms->modules_count; i++) {
struct mod *mod = mod_syms->modules[i];
struct kmod_list *l, *list = NULL;
int err = kmod_module_get_symbols(mod->kmod, &list);
if (err < 0) {
Expand All @@ -1611,7 +1619,21 @@
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(mod_syms->depmod, name, false, crc,
mod);
if (sym == NULL) {
kmod_module_symbols_free_list(list);
return (void *)(intptr_t)-ENOMEM;
}

err = array_append(&mod_syms->symbols, sym);
if (err < 0) {
free(sym);
kmod_module_symbols_free_list(list);
return (void *)(intptr_t)-ENOMEM;
}
}
kmod_module_symbols_free_list(list);

Expand All @@ -1623,29 +1645,119 @@
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 (void *)(intptr_t)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 (void *)(intptr_t)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 (void *)(intptr_t)err;
continue;
}
}
kmod_module_get_dependency_symbols(mod->kmod, &mod->dep_sym_list);
kmod_module_unref(mod->kmod);
mod->kmod = NULL;
}
return (void *)(intptr_t)0;
}

static unsigned int get_cpu_count(void)
{
long nproc = sysconf(_SC_NPROCESSORS_ONLN);
return nproc > 0 ? (unsigned int)nproc : 1;
}

static int depmod_load_modules(struct depmod *depmod)
{
struct thread_info {
pthread_t tid;
struct module_symbols mod_syms;
} *tinfo;
unsigned int n_threads;
size_t modules_per_thread, last_modules_per_thread;
int err;

DBG("load symbols (%zu modules)\n", depmod->modules.count);

n_threads = get_cpu_count();
if (n_threads > depmod->modules.count)
n_threads = depmod->modules.count;

tinfo = calloc(n_threads, sizeof(*tinfo));
if (tinfo == NULL)
return -ENOMEM;

modules_per_thread = (depmod->modules.count + n_threads - 1) / n_threads;
last_modules_per_thread =
modules_per_thread - (depmod->modules.count % n_threads);

for (unsigned int i = 0; i < n_threads; i++) {
struct module_symbols *mod_syms = &tinfo[i].mod_syms;

mod_syms->depmod = depmod;
mod_syms->modules =
(struct mod **)depmod->modules.array + (i * modules_per_thread);
mod_syms->modules_count = modules_per_thread;
if (i + 1 == n_threads)
mod_syms->modules_count = last_modules_per_thread;

err = pthread_create(&tinfo[i].tid, NULL, &resolve_module_symbols,
mod_syms);
if (err != 0) {
err = -err; // Most/all pthread API returns positive error
n_threads = i;
break;
}
}

for (unsigned int i = 0; i < n_threads; i++) {
int local_err;
void *res;

local_err = pthread_join(tinfo[i].tid, &res);
if (err == 0) {
if (local_err != 0)
err = -local_err;
if ((int)(intptr_t)res != 0)
err = (int)(intptr_t)res;
}
}

if (err != 0) {
for (unsigned int i = 0; i < n_threads; i++) {
struct module_symbols *mod_syms = &tinfo[i].mod_syms;

for (size_t j = 0; j < mod_syms->symbols.count; j++)
free(mod_syms->symbols.array[j]);

array_free_array(&mod_syms->symbols);
}
free(tinfo);
return err;
}

for (unsigned int i = 0; i < n_threads; i++) {
struct module_symbols *mod_syms = &tinfo[i].mod_syms;

for (size_t j = 0; j < mod_syms->symbols.count; j++)
depmod_symbol_add(depmod, mod_syms->symbols.array[j]);

array_free_array(&mod_syms->symbols);
}
free(tinfo);

DBG("loaded symbols (%zu modules, %u symbols)\n", depmod->modules.count,
hash_get_count(depmod->symbols));
Expand Down Expand Up @@ -2642,13 +2754,24 @@

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 +2790,7 @@

/* 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 +2814,9 @@
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 +2844,7 @@

/* 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 +2870,10 @@
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
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