[PATCH 3.16 10/86] module, jump_label: Fix module locking

Ben Hutchings
2019-05-16T16:05:13Z

From: Peter Zijlstra <peterz@infradead.org>

commit bed831f9a251968272dae10a83b512c7db256ef0 upstream.

As per the module core lockdep annotations in the coming patch:

[ 18.034047] ---[ end trace 9294429076a9c673 ]---
[ 18.047760] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
[ 18.059228] ffffffff817d8676 ffff880036683c38 ffffffff8157e98b 0000000000000001
[ 18.067541] 0000000000000000 ffff880036683c78 ffffffff8105fbc7 ffff880036683c68
[ 18.075851] ffffffffa0046b08 0000000000000000 ffffffffa0046d00 ffffffffa0046cc8
[ 18.084173] Call Trace:
[ 18.086906] [<ffffffff8157e98b>] dump_stack+0x4f/0x7b
[ 18.092649] [<ffffffff8105fbc7>] warn_slowpath_common+0x97/0xe0
[ 18.099361] [<ffffffff8105fc2a>] warn_slowpath_null+0x1a/0x20
[ 18.105880] [<ffffffff810ee502>] __module_address+0x1d2/0x1e0
[ 18.112400] [<ffffffff81161153>] jump_label_module_notify+0x143/0x1e0
[ 18.119710] [<ffffffff810814bf>] notifier_call_chain+0x4f/0x70
[ 18.126326] [<ffffffff8108160e>] __blocking_notifier_call_chain+0x5e/0x90
[ 18.134009] [<ffffffff81081656>] blocking_notifier_call_chain+0x16/0x20
[ 18.141490] [<ffffffff810f0f00>] load_module+0x1b50/0x2660
[ 18.147720] [<ffffffff810f1ade>] SyS_init_module+0xce/0x100
[ 18.154045] [<ffffffff81587429>] system_call_fastpath+0x12/0x17
[ 18.160748] ---[ end trace 9294429076a9c674 ]---

Jump labels is not doing it right; fix this.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jason Baron <jbaron@akamai.com>
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
kernel/jump_label.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -309,7 +309,7 @@ static int jump_label_add_module(struct
continue;

key = iterk;
- if (__module_address(iter->key) == mod) {
+ if (within_module(iter->key, mod)) {
/*
* Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
*/
@@ -346,7 +346,7 @@ static void jump_label_del_module(struct

key = (struct static_key *)(unsigned long)iter->key;

- if (__module_address(iter->key) == mod)
+ if (within_module(iter->key, mod))
continue;

prev = &key->next;
@@ -450,14 +450,16 @@ static void jump_label_update(struct sta
{
struct jump_entry *stop = __stop___jump_table;
struct jump_entry *entry = jump_label_get_entries(key);
-
#ifdef CONFIG_MODULES
- struct module *mod = __module_address((unsigned long)key);
+ struct module *mod;

__jump_label_mod_update(key, enable);

+ preempt_disable();
+ mod = __module_address((unsigned long)key);
if (mod)
stop = mod->jump_entries + mod->num_jump_entries;
+ preempt_enable();
#endif
/* if there are no users, entry can be NULL */
if (entry)