diff options
author | Matthew Sakai <msakai@redhat.com> | 2023-11-17 03:47:35 +0300 |
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committer | Mike Snitzer <snitzer@kernel.org> | 2024-02-20 21:43:13 +0300 |
commit | 89f9b701f5b800daa76506d5bba197624e97ee44 (patch) | |
tree | f05a29f7240ada9944228a8730f8ea65c3dacfc5 /drivers/md/dm-vdo/thread-registry.c | |
parent | 4fcb4290dfe303de048fe01968513da6f4512147 (diff) | |
download | linux-89f9b701f5b800daa76506d5bba197624e97ee44.tar.xz |
dm vdo: add thread and synchronization utilities
This patch adds utilities for managing and using named threads, as well as
several locking and synchronization utilities. These utilities help dm-vdo
minimize thread transitions and manage interactions between threads.
Co-developed-by: J. corwin Coburn <corwin@hurlbutnet.net>
Signed-off-by: J. corwin Coburn <corwin@hurlbutnet.net>
Co-developed-by: Michael Sclafani <dm-devel@lists.linux.dev>
Signed-off-by: Michael Sclafani <dm-devel@lists.linux.dev>
Co-developed-by: Thomas Jaskiewicz <tom@jaskiewicz.us>
Signed-off-by: Thomas Jaskiewicz <tom@jaskiewicz.us>
Co-developed-by: Bruce Johnston <bjohnsto@redhat.com>
Signed-off-by: Bruce Johnston <bjohnsto@redhat.com>
Co-developed-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to 'drivers/md/dm-vdo/thread-registry.c')
-rw-r--r-- | drivers/md/dm-vdo/thread-registry.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/thread-registry.c b/drivers/md/dm-vdo/thread-registry.c new file mode 100644 index 000000000000..8c887158c224 --- /dev/null +++ b/drivers/md/dm-vdo/thread-registry.c @@ -0,0 +1,92 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2023 Red Hat + */ + +#include "thread-registry.h" + +#include <linux/rculist.h> + +#include "permassert.h" + +/* + * We need to be careful when using other facilities that may use thread registry functions in + * their normal operation. For example, we do not want to invoke the logger while holding a lock. + */ + +void uds_initialize_thread_registry(struct thread_registry *registry) +{ + INIT_LIST_HEAD(®istry->links); + spin_lock_init(®istry->lock); +} + +/* Register the current thread and associate it with a data pointer. */ +void uds_register_thread(struct thread_registry *registry, + struct registered_thread *new_thread, const void *pointer) +{ + struct registered_thread *thread; + bool found_it = false; + + INIT_LIST_HEAD(&new_thread->links); + new_thread->pointer = pointer; + new_thread->task = current; + + spin_lock(®istry->lock); + list_for_each_entry(thread, ®istry->links, links) { + if (thread->task == current) { + /* There should be no existing entry. */ + list_del_rcu(&thread->links); + found_it = true; + break; + } + } + list_add_tail_rcu(&new_thread->links, ®istry->links); + spin_unlock(®istry->lock); + + ASSERT_LOG_ONLY(!found_it, "new thread not already in registry"); + if (found_it) { + /* Ensure no RCU iterators see it before re-initializing. */ + synchronize_rcu(); + INIT_LIST_HEAD(&thread->links); + } +} + +void uds_unregister_thread(struct thread_registry *registry) +{ + struct registered_thread *thread; + bool found_it = false; + + spin_lock(®istry->lock); + list_for_each_entry(thread, ®istry->links, links) { + if (thread->task == current) { + list_del_rcu(&thread->links); + found_it = true; + break; + } + } + spin_unlock(®istry->lock); + + ASSERT_LOG_ONLY(found_it, "thread found in registry"); + if (found_it) { + /* Ensure no RCU iterators see it before re-initializing. */ + synchronize_rcu(); + INIT_LIST_HEAD(&thread->links); + } +} + +const void *uds_lookup_thread(struct thread_registry *registry) +{ + struct registered_thread *thread; + const void *result = NULL; + + rcu_read_lock(); + list_for_each_entry_rcu(thread, ®istry->links, links) { + if (thread->task == current) { + result = thread->pointer; + break; + } + } + rcu_read_unlock(); + + return result; +} |