linux-stable/fs/dlm/Kconfig
Alexander Aring a47666eb76 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 <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2020-08-27 15:59:09 -05:00

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# SPDX-License-Identifier: GPL-2.0-only
menuconfig DLM
tristate "Distributed Lock Manager (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.
config DLM_DEBUG
bool "DLM debugging"
depends on DLM
help
Under the debugfs mount point, the name of each lockspace will
appear as a file in the "dlm" directory. The output is the
list of resource and locks the local node knows about.