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module: Use RCU in find_module_all().

The modules list and module::kallsyms can be accessed under RCU assumption. Remove module_assert_mutex_or_preempt() from find_module_all() so it can be used under RCU protection without warnings. Update its callers to use RCU protection instead of preempt_disable().

Sebastian Andrzej Siewior committed 1 year ago

Commit febaa651 parent c4fadf35 files · +8 −14Browse files

Showing the changes to kernel/module (2 of 5 files). Show all

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2 files
  1. kernel/module/kallsyms.c +1 −0
  2. kernel/module/main.c +2 −4
kernel/module/kallsyms.c+1−0
@@ -450,6 +450,7 @@ unsigned long module_kallsyms_lookup_name(const char *name) · 449 unmodified lines
450 unsigned long ret;450 unsigned long ret;
451 451
452 /* Don't lock: we're in enough trouble already. */452 /* Don't lock: we're in enough trouble already. */
453 guard(rcu)();
453 preempt_disable();454 preempt_disable();
454 ret = __module_kallsyms_lookup_name(name);455 ret = __module_kallsyms_lookup_name(name);
455 preempt_enable();456 preempt_enable();
kernel/module/main.c+2−4
@@ -374,16 +374,14 @@ bool find_symbol(struct find_symbol_arg *fsa) · 373 unmodified lines
374}374}
375 375
376/*376/*
377 * Search for module by name: must hold module_mutex (or preempt disabled377 * Search for module by name: must hold module_mutex (or RCU for read-only
378 * for read-only access).378 * access).
379 */379 */
380struct module *find_module_all(const char *name, size_t len,380struct module *find_module_all(const char *name, size_t len,
381 bool even_unformed)381 bool even_unformed)
382{382{
383 struct module *mod;383 struct module *mod;
384 384
385 module_assert_mutex_or_preempt();
386
387 list_for_each_entry_rcu(mod, &modules, list,385 list_for_each_entry_rcu(mod, &modules, list,
388 lockdep_is_held(&module_mutex)) {386 lockdep_is_held(&module_mutex)) {
389 if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)387 if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)