diff options
| author | Andy Zhou <azhou@von.org> | 2015-11-13 18:39:37 -0800 |
|---|---|---|
| committer | Andy Zhou <azhou@ovn.org> | 2015-11-19 13:13:20 -0800 |
| commit | e9d6808ca6bfeb6b8d1ca30113c186098e4d2d56 (patch) | |
| tree | 4f8c0c7024e1d5cb7d439cff6335a04e66126493 /lib/vlog.c | |
| parent | 10d8e9c6719530a317dfe657442b10023f2aec5d (diff) | |
| download | openvswitch-e9d6808ca6bfeb6b8d1ca30113c186098e4d2d56.tar.gz | |
vlog: Fix a deadlock bug.
Calling VLOG_FATAL() while holding the 'log_file_mutex" may lead to
deadlock since VLOG_FATAL() implementation tries to acquire the
same lock. Fix this by building the error message first, then
call VLOG_FATAL() after the 'log_file_mutex' has been released.
This bug is not likely show up in practice since chown() usually
won't fail. It is still better to have a correct implementation.
Reported-by: Daniele Di Proietto <ddiproietto@vmware.com>
Signed-off-by: Andy Zhou <azhou@ovn.org>
Acked-by: Daniele Di Proietto <ddiproietto@vmware.com>
Diffstat (limited to 'lib/vlog.c')
| -rw-r--r-- | lib/vlog.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/lib/vlog.c b/lib/vlog.c index a4aa2a090..28cea5ddb 100644 --- a/lib/vlog.c +++ b/lib/vlog.c @@ -438,15 +438,24 @@ vlog_reopen_log_file(void) void vlog_change_owner_unix(uid_t user, gid_t group) { - ovs_mutex_lock(&log_file_mutex); - int error = log_file_name ? chown(log_file_name, user, group) : 0; + struct ds err = DS_EMPTY_INITIALIZER; + int error; + ovs_mutex_lock(&log_file_mutex); + error = log_file_name ? chown(log_file_name, user, group) : 0; if (error) { - VLOG_FATAL("Failed to change %s ownership: %s.", - log_file_name, ovs_strerror(errno)); + /* Build the error message. We can not call VLOG_FATAL directly + * here because VLOG_FATAL() will try again to to acquire + * 'log_file_mutex' lock, causing deadlock. + */ + ds_put_format(&err, "Failed to change %s ownership: %s.", + log_file_name, ovs_strerror(errno)); } - ovs_mutex_unlock(&log_file_mutex); + + if (error) { + VLOG_FATAL("%s", ds_steal_cstr(&err)); + } } #endif |