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client: fix race between callback and io list re-assignment

This commit is contained in:
Thomas Schoebel-Theuer 2021-04-16 12:16:09 +02:00
parent 320e9335c9
commit ef7936bd0d
1 changed files with 17 additions and 5 deletions
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22
kernel/mars_client.c
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@ -555,8 +555,6 @@ int receiver_thread(void *data)
while (brick->power.button && !brick_thread_should_stop()) {
struct mars_cmd cmd = {};
struct list_head *tmp;
struct client_mref_aspect *mref_a = NULL;
struct mref_object *mref = NULL;
if (ch->recv_error) {
/* The protocol may be out of sync.
@ -598,17 +596,29 @@ int receiver_thread(void *data)
break;
case CMD_CB:
{
struct mref_object *mref = NULL;
struct client_mref_aspect *mref_a = NULL;
unsigned long id = READ_ONCE(cmd.cmd_int1);
unsigned int hash_index = CLIENT_HASH_FN(id);
mutex_lock(&output->mutex);
for (tmp = output->hash_table[hash_index].next; tmp != &output->hash_table[hash_index]; tmp = tmp->next) {
struct mref_object *tmp_mref;
mref_a = container_of(tmp, struct client_mref_aspect, hash_head);
tmp_mref = mref_a->object;
struct client_mref_aspect *tmp_mref_a;
tmp_mref_a = container_of(tmp, struct client_mref_aspect, hash_head);
/* Treat any non-members of io lists as absent.
* This may happen during re-assignment to another io list.
*/
if (unlikely(list_empty(&tmp_mref_a->io_head)))
continue;
tmp_mref = tmp_mref_a->object;
CHECK_PTR(tmp_mref, err);
if (READ_ONCE(tmp_mref->ref_id) != cmd.cmd_int1)
continue;
mref_a = tmp_mref_a;
mref = tmp_mref;
list_del_init(&mref_a->hash_head);
list_del_init(&mref_a->io_head);
@ -621,7 +631,7 @@ int receiver_thread(void *data)
}
mutex_unlock(&output->mutex);
if (unlikely(!mref)) {
if (unlikely(!mref || !mref_a)) {
MARS_WRN("got unknown callback id %d on '%s' @%s\n",
cmd.cmd_int1,
output->bundle.path,
@ -1073,6 +1083,7 @@ void client_reset_statistics(struct client_brick *brick)
static int client_mref_aspect_init_fn(struct generic_aspect *_ini)
{
struct client_mref_aspect *ini = (void*)_ini;
INIT_LIST_HEAD(&ini->io_head);
INIT_LIST_HEAD(&ini->hash_head);
INIT_LIST_HEAD(&ini->tmp_head);
@ -1082,6 +1093,7 @@ static int client_mref_aspect_init_fn(struct generic_aspect *_ini)
static void client_mref_aspect_exit_fn(struct generic_aspect *_ini)
{
struct client_mref_aspect *ini = (void*)_ini;
CHECK_HEAD_EMPTY(&ini->io_head);
CHECK_HEAD_EMPTY(&ini->hash_head);
}