pespin has uploaded this change for review. ( https://gerrit.osmocom.org/c/libosmocore/+/41986?usp=email )

Change subject: logging: Also Avoid infinite loop/deadlock in log_check_level() ......................................................................

logging: Also Avoid infinite loop/deadlock in log_check_level()

A LOG() macro being called inside an already-logging path will first call log_check_level() before calling osmo_vlogp(). Since calling happens with the mutex hold, it has been seen to deadlock in eg. osmo-hnbgw.

Change-Id: I0098629b335b3aa174b49fd79c33d22b04bc4785 --- M src/core/logging.c 1 file changed, 9 insertions(+), 1 deletion(-)

git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/86/41986/1

diff --git a/src/core/logging.c b/src/core/logging.c index 60634af..db5433e 100644 --- a/src/core/logging.c +++ b/src/core/logging.c @@ -753,7 +753,8 @@ if (OSMO_UNLIKELY(log_thread_state.logging_active)) { /* Avoid re-entrant logging: If logging to log target generates * extra logging (eg. an error log line due to some wqueue being full), - * we may end up in an infinite loop. */ + * we may end up in an infinite loop, or deadlock trying to re-acquire + * this same lock. */ return; } log_thread_state.logging_active = true; @@ -1397,6 +1398,13 @@

/* TODO: The following could/should be cached (update on config) */

+ if (OSMO_UNLIKELY(log_thread_state.logging_active)) { + /* Avoid re-entrant logging: If logging to log target generates + * extra logging (eg. an error log line due to some wqueue being full), + * we may end up in an infinite loop, or deadlock trying to re-acquire + * this same lock. */ + return 0; + } log_tgt_mutex_lock();

llist_for_each_entry(tar, &osmo_log_target_list, entry) {