path: root/kernel/Makefile
diff options
authorPaul E. McKenney <>2006-10-04 02:17:02 -0700
committerLinus Torvalds <>2006-10-04 07:55:30 -0700
commit621934ee7ed5b073c7fd638b347e632c53572761 (patch)
tree5722f9cda22c099ad60545f963410dcbc762ee65 /kernel/Makefile
parent95d77884c77beed676036d2f74d10b470a483c63 (diff)
[PATCH] srcu-3: RCU variant permitting read-side blocking
Updated patch adding a variant of RCU that permits sleeping in read-side critical sections. SRCU is as follows: o Each use of SRCU creates its own srcu_struct, and each srcu_struct has its own set of grace periods. This is critical, as it prevents one subsystem with a blocking reader from holding up SRCU grace periods for other subsystems. o The SRCU primitives (srcu_read_lock(), srcu_read_unlock(), and synchronize_srcu()) all take a pointer to a srcu_struct. o The SRCU primitives must be called from process context. o srcu_read_lock() returns an int that must be passed to the matching srcu_read_unlock(). Realtime RCU avoids the need for this by storing the state in the task struct, but SRCU needs to allow a given code path to pass through multiple SRCU domains -- storing state in the task struct would therefore require either arbitrary space in the task struct or arbitrary limits on SRCU nesting. So I kicked the state-storage problem up to the caller. Of course, it is not permitted to call synchronize_srcu() while in an SRCU read-side critical section. o There is no call_srcu(). It would not be hard to implement one, but it seems like too easy a way to OOM the system. (Hey, we have enough trouble with call_rcu(), which does -not- permit readers to sleep!!!) So, if you want it, please tell me why... [ sparse notation] Signed-off-by: Paul E. McKenney <> Signed-off-by: Josh Triplett <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'kernel/Makefile')
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index d948ca12acf0..5e3f3b75563a 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -8,7 +8,7 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
signal.o sys.o kmod.o workqueue.o pid.o \
rcupdate.o extable.o params.o posix-timers.o \
kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
- hrtimer.o rwsem.o latency.o nsproxy.o
+ hrtimer.o rwsem.o latency.o nsproxy.o srcu.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += time/