From a47666eb763cc1b8b48bd88185ca56676f40ca89 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Thu, 27 Aug 2020 15:02:49 -0400 Subject: fs: dlm: make connection hash lockless There are some problems with the connections_lock. During my experiements I saw sometimes circular dependencies with sock_lock. The reason here might be code parts which runs nodeid2con() before or after sock_lock is acquired. Another issue are missing locks in for_conn() iteration. Maybe this works fine because for_conn() is running in a context where connection_hash cannot be manipulated by others anymore. However this patch changes the connection_hash to be protected by sleepable rcu. The hotpath function __find_con() is implemented lockless as it is only a reader of connection_hash and this hopefully fixes the circular locking dependencies. The iteration for_conn() will still call some sleepable functionality, that's why we use sleepable rcu in this case. This patch removes the kmemcache functionality as I think I need to make some free() functionality via call_rcu(). However allocation time isn't here an issue. The dlm_allow_con will not be protected by a lock anymore as I think it's enough to just set and flush workqueues afterwards. Signed-off-by: Alexander Aring Signed-off-by: David Teigland --- fs/dlm/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/dlm/Kconfig') diff --git a/fs/dlm/Kconfig b/fs/dlm/Kconfig index f82a4952769d..ee92634196a8 100644 --- a/fs/dlm/Kconfig +++ b/fs/dlm/Kconfig @@ -4,6 +4,7 @@ menuconfig DLM depends on INET depends on SYSFS && CONFIGFS_FS && (IPV6 || IPV6=n) select IP_SCTP + select SRCU help A general purpose distributed lock manager for kernel or userspace applications. -- cgit v1.2.3