The patch titled
RCU: introduce rcu_needs_cpu() interface
has been added to the -mm tree. Its filename is
rcu-introduce-rcu_needs_cpu-interface.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>,
"Paul E. McKenney" <paulmck@xxxxxxxxxx>
Introduce rcu_needs_cpu() interface. This can be used to tell if there
will be a new rcu batch on a cpu soon by looking at the curlist pointer.
This can be used to avoid to enter a tickless idle state where the cpu
would miss that a new batch is ready when rcu_start_batch would be called
on a different cpu.
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/rcupdate.h | 1 +
kernel/rcupdate.c | 8 ++++++++
2 files changed, 9 insertions(+)
diff -puN include/linux/rcupdate.h~rcu-introduce-rcu_needs_cpu-interface include/linux/rcupdate.h
--- 25/include/linux/rcupdate.h~rcu-introduce-rcu_needs_cpu-interface Wed Apr 26 14:12:13 2006
+++ 25-akpm/include/linux/rcupdate.h Wed Apr 26 14:12:13 2006
@@ -132,6 +132,7 @@ static inline void rcu_bh_qsctr_inc(int
}
extern int rcu_pending(int cpu);
+extern int rcu_needs_cpu(int cpu);
/**
* rcu_read_lock - mark the beginning of an RCU read-side critical section.
diff -puN kernel/rcupdate.c~rcu-introduce-rcu_needs_cpu-interface kernel/rcupdate.c
--- 25/kernel/rcupdate.c~rcu-introduce-rcu_needs_cpu-interface Wed Apr 26 14:12:13 2006
+++ 25-akpm/kernel/rcupdate.c Wed Apr 26 14:12:13 2006
@@ -485,6 +485,14 @@ int rcu_pending(int cpu)
__rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu));
}
+int rcu_needs_cpu(int cpu)
+{
+ struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+ struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu);
+
+ return (!!rdp->curlist || !!rdp_bh->curlist || rcu_pending(cpu));
+}
+
void rcu_check_callbacks(int cpu, int user)
{
if (user ||
_
Patches currently in -mm which might be from heiko.carstens@xxxxxxxxxx are
s390-make-qeth-buildable.patch
ipv4-inet_init-fs_initcall.patch
s390-bug-in-setup_rt_frame.patch
s390-instruction-processing-damage-handling.patch
rcu-introduce-rcu_needs_cpu-interface.patch
s390-exploit-rcu_needs_cpu-interface.patch
-
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