module: Sanitize RCU usage and locking
Currently the RCU usage in module is an inconsistent mess of RCU and
RCU-sched, this is broken for CONFIG_PREEMPT where synchronize_rcu()
does not imply synchronize_sched().
Most usage sites use preempt_{dis,en}able() which is RCU-sched, but
(most of) the modification sites use synchronize_rcu(). With the
exception of the module bug list, which actually uses RCU.
Convert everything over to RCU-sched.
Furthermore add lockdep asserts to all sites, because it's not at all
clear to me the required locking is observed, esp. on exported
functions.
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/lib/bug.c b/lib/bug.c
index 0c3bd95..cff145f 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -66,7 +66,7 @@
struct module *mod;
const struct bug_entry *bug = NULL;
- rcu_read_lock();
+ rcu_read_lock_sched();
list_for_each_entry_rcu(mod, &module_bug_list, bug_list) {
unsigned i;
@@ -77,7 +77,7 @@
}
bug = NULL;
out:
- rcu_read_unlock();
+ rcu_read_unlock_sched();
return bug;
}
@@ -88,6 +88,8 @@
char *secstrings;
unsigned int i;
+ lockdep_assert_held(&module_mutex);
+
mod->bug_table = NULL;
mod->num_bugs = 0;
@@ -113,6 +115,7 @@
void module_bug_cleanup(struct module *mod)
{
+ lockdep_assert_held(&module_mutex);
list_del_rcu(&mod->bug_list);
}