From 0b9902c1fcc59ba75268386c0420a554f8844168 Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Thu, 7 Jan 2021 18:24:40 +0100 Subject: s390/qeth: fix deadlock during recovery When qeth_dev_layer2_store() - holding the discipline_mutex - waits inside qeth_l*_remove_device() for a qeth_do_reset() thread to complete, we can hit a deadlock if qeth_do_reset() concurrently calls qeth_set_online() and thus tries to aquire the discipline_mutex. Move the discipline_mutex locking outside of qeth_set_online() and qeth_set_offline(), and turn the discipline into a parameter so that callers understand the dependency. To fix the deadlock, we can now relax the locking: As already established, qeth_l*_remove_device() waits for qeth_do_reset() to complete. So qeth_do_reset() itself is under no risk of having card->discipline ripped out while it's running, and thus doesn't need to take the discipline_mutex. Fixes: 9dc48ccc68b9 ("qeth: serialize sysfs-triggered device configurations") Signed-off-by: Julian Wiedmann Reviewed-by: Alexandra Winter Signed-off-by: Jakub Kicinski --- drivers/s390/net/qeth_core.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/s390/net/qeth_core.h') diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h index 6f5ddc3eab8c..28f637042d44 100644 --- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -1079,7 +1079,8 @@ struct qeth_card *qeth_get_card_by_busid(char *bus_id); void qeth_set_allowed_threads(struct qeth_card *card, unsigned long threads, int clear_start_mask); int qeth_threads_running(struct qeth_card *, unsigned long); -int qeth_set_offline(struct qeth_card *card, bool resetting); +int qeth_set_offline(struct qeth_card *card, const struct qeth_discipline *disc, + bool resetting); int qeth_send_ipa_cmd(struct qeth_card *, struct qeth_cmd_buffer *, int (*reply_cb) -- cgit