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module: Use RCU in find_module_all().

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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().

Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-trace-kernel@vger.kernel.org
Cc: live-patching@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250108090457.512198-7-bigeasy@linutronix.de
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
This commit is contained in:
Sebastian Andrzej Siewior 2025-01-08 10:04:35 +01:00 committed by Petr Pavlu
parent c4fadf38de
commit febaa65c94
5 changed files with 8 additions and 14 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
include/linux/module.h
View file

@ -666,7 +666,7 @@ static inline bool within_module(unsigned long addr, const struct module *mod)
return within_module_init(addr, mod) || within_module_core(addr, mod);
}
/* Search for module by name: must be in a RCU-sched critical section. */
/* Search for module by name: must be in a RCU critical section. */
struct module *find_module(const char *name);
extern void __noreturn __module_put_and_kthread_exit(struct module *mod,

4
kernel/livepatch/core.c
View file

@ -59,7 +59,7 @@ static void klp_find_object_module(struct klp_object *obj)
if (!klp_is_module(obj))
return;
rcu_read_lock_sched();
guard(rcu)();
/*
* We do not want to block removal of patched modules and therefore
* we do not take a reference here. The patches are removed by
@ -75,8 +75,6 @@ static void klp_find_object_module(struct klp_object *obj)
*/
if (mod && mod->klp_alive)
obj->mod = mod;
rcu_read_unlock_sched();
}
static bool klp_initialized(void)

1
kernel/module/kallsyms.c
View file

@ -450,6 +450,7 @@ unsigned long module_kallsyms_lookup_name(const char *name)
unsigned long ret;
/* Don't lock: we're in enough trouble already. */
guard(rcu)();
preempt_disable();
ret = __module_kallsyms_lookup_name(name);
preempt_enable();

6
kernel/module/main.c
View file

@ -374,16 +374,14 @@ bool find_symbol(struct find_symbol_arg *fsa)
}
/*
* Search for module by name: must hold module_mutex (or preempt disabled
* for read-only access).
* Search for module by name: must hold module_mutex (or RCU for read-only
* access).
*/
struct module *find_module_all(const char *name, size_t len,
bool even_unformed)
{
struct module *mod;
module_assert_mutex_or_preempt();
list_for_each_entry_rcu(mod, &modules, list,
lockdep_is_held(&module_mutex)) {
if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)

7
kernel/trace/trace_kprobe.c
View file

@ -124,9 +124,8 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
if (!p)
return true;
*p = '\0';
rcu_read_lock_sched();
scoped_guard(rcu)
ret = !!find_module(tk->symbol);
rcu_read_unlock_sched();
*p = ':';
return ret;
@ -796,12 +795,10 @@ static struct module *try_module_get_by_name(const char *name)
{
struct module *mod;
rcu_read_lock_sched();
guard(rcu)();
mod = find_module(name);
if (mod && !try_module_get(mod))
mod = NULL;
rcu_read_unlock_sched();
return mod;
}
#else