Changeset 3679f51a in mainline for uspace/lib/c/generic/rcu.c

Timestamp:

2018-06-25T20:41:09Z (6 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

95838f1

Parents:

d73d992

git-author:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-06-25 20:30:35)

git-committer:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-06-25 20:41:09)

Message:

Remove the option of RCU-upgradable futexes for now.
They complicate threading design too much.

File:

• uspace/lib/c/generic/rcu.c (modified) (10 diffs)

uspace/lib/c/generic/rcu.c

@@ -150 +150 @@
 
 
-static void wait_for_readers(size_t reader_group, blocking_mode_t blocking_mode);
+static void wait_for_readers(size_t reader_group);
 static void force_mb_in_all_threads(void);
 static bool is_preexisting_reader(const fibril_rcu_data_t *fib, size_t group);
 
-static void lock_sync(blocking_mode_t blocking_mode);
+static void lock_sync(void);
 static void unlock_sync(void);
-static void sync_sleep(blocking_mode_t blocking_mode);
+static void sync_sleep(void);
 
 static bool is_in_group(size_t nesting_cnt, size_t group);
@@ -242 +242 @@
 
 /** Blocks until all preexisting readers exit their critical sections. */
-void _rcu_synchronize(blocking_mode_t blocking_mode)
+void rcu_synchronize(void)
 {
         assert(!rcu_read_locked());
@@ -252 +252 @@
         size_t gp_in_progress = ACCESS_ONCE(rcu.cur_gp);
 
-        lock_sync(blocking_mode);
+        lock_sync();
 
         /*
@@ -300 +300 @@
 
         size_t new_reader_group = get_other_group(rcu.reader_group);
-        wait_for_readers(new_reader_group, blocking_mode);
+        wait_for_readers(new_reader_group);
 
         /* Separates waiting for readers in new_reader_group from group flip. */
@@ -312 +312 @@
         memory_barrier();
 
-        wait_for_readers(old_reader_group, blocking_mode);
+        wait_for_readers(old_reader_group);
 
         /* MB_FORCE_U  */
@@ -332 +332 @@
 
 /** Waits for readers of reader_group to exit their readers sections. */
-static void wait_for_readers(size_t reader_group, blocking_mode_t blocking_mode)
+static void wait_for_readers(size_t reader_group)
 {
         futex_down(&rcu.list_futex);
@@ -346 +346 @@
                         if (is_preexisting_reader(fib, reader_group)) {
                                 futex_up(&rcu.list_futex);
-                                sync_sleep(blocking_mode);
+                                sync_sleep();
                                 futex_down(&rcu.list_futex);
                                 /* Break to while loop. */
@@ -361 +361 @@
 }
 
-static void lock_sync(blocking_mode_t blocking_mode)
+static void lock_sync(void)
 {
         futex_down(&rcu.sync_lock.futex);
         if (rcu.sync_lock.locked) {
-                if (blocking_mode == BM_BLOCK_FIBRIL) {
-                        blocked_fibril_t blocked_fib;
-                        blocked_fib.id = fibril_get_id();
-
-                        list_append(&blocked_fib.link, &rcu.sync_lock.blocked_fibrils);
-
-                        do {
-                                blocked_fib.is_ready = false;
-                                futex_up(&rcu.sync_lock.futex);
-                                fibril_switch(FIBRIL_TO_MANAGER);
-                                futex_down(&rcu.sync_lock.futex);
-                        } while (rcu.sync_lock.locked);
-
-                        list_remove(&blocked_fib.link);
-                        rcu.sync_lock.locked = true;
-                } else {
-                        assert(blocking_mode == BM_BLOCK_THREAD);
-                        rcu.sync_lock.blocked_thread_cnt++;
+                blocked_fibril_t blocked_fib;
+                blocked_fib.id = fibril_get_id();
+
+                list_append(&blocked_fib.link, &rcu.sync_lock.blocked_fibrils);
+
+                do {
+                        blocked_fib.is_ready = false;
                         futex_up(&rcu.sync_lock.futex);
-                        futex_down(&rcu.sync_lock.futex_blocking_threads);
-                }
+                        fibril_switch(FIBRIL_TO_MANAGER);
+                        futex_down(&rcu.sync_lock.futex);
+                } while (rcu.sync_lock.locked);
+
+                list_remove(&blocked_fib.link);
+                rcu.sync_lock.locked = true;
         } else {
                 rcu.sync_lock.locked = true;
@@ -420 +413 @@
 }
 
-static void sync_sleep(blocking_mode_t blocking_mode)
+static void sync_sleep(void)
 {
         assert(rcu.sync_lock.locked);
@@ -428 +421 @@
          */
         futex_up(&rcu.sync_lock.futex);
-
-        if (blocking_mode == BM_BLOCK_FIBRIL) {
-                async_usleep(RCU_SLEEP_MS * 1000);
-        } else {
-                thread_usleep(RCU_SLEEP_MS * 1000);
-        }
-
+        async_usleep(RCU_SLEEP_MS * 1000);
         futex_down(&rcu.sync_lock.futex);
 }