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

kernel/module/kallsyms.c +1 −0
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	450	unsigned long ret;
451	451
452	452	/* Don't lock: we're in enough trouble already. */
	453	+ guard(rcu)();
453	454	preempt_disable();
454	455	ret = __module_kallsyms_lookup_name(name);
455	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 disabled
378		− * for read-only access).
	377	+ * Search for module by name: must hold module_mutex (or RCU for read-only
	378	+ * access).
379	379	*/
380	380	struct module find_module_all(const char name, size_t len,
381	381	bool even_unformed)
382	382	{
383	383	struct module *mod;
384	384
385		− module_assert_mutex_or_preempt();
386		−
387	385	list_for_each_entry_rcu(mod, &modules, list,
388	386	lockdep_is_held(&module_mutex)) {
389	387	if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)