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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-04-16 12:12:09 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-04-17 07:30:54 -0700
commit92c38702e98e58438c3760ebb279c40bbca8bd5f (patch)
tree775d0078f46b6d9f2fc4d4be83b80e8376a707ba /kernel
parent0034102808e0dbbf3a2394b82b1bb40b5778de9e (diff)
downloadlinux-92c38702e98e58438c3760ebb279c40bbca8bd5f.tar.gz
rcu: Permit call_rcu() from CPU_DYING notifiers
As of: 29494be71afe ("rcu,cleanup: simplify the code when cpu is dying") RCU adopts callbacks from the dying CPU in its CPU_DYING notifier, which means that any callbacks posted by later CPU_DYING notifiers are ignored until the CPU comes back online. A WARN_ON_ONCE() was added to __call_rcu() by: e56014000816 ("rcu: Simplify offline processing") to check for this condition. Although this condition did not trigger (at least as far as I know) during -next testing, it did recently trigger in mainline: https://lkml.org/lkml/2012/4/2/34 What is needed longer term is for RCU's CPU_DEAD notifier to adopt any callbacks that were posted by CPU_DYING notifiers, however, the Linux kernel has been running with this sort of thing happening for quite some time. So the only thing that qualifies as a regression is the WARN_ON_ONCE(), which this commit removes. Making RCU's CPU_DEAD notifier adopt callbacks posted by CPU_DYING notifiers is a topic for the 3.5 release of the Linux kernel. Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rcutree.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 1050d6d3922..d0c5baf1ab1 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1820,7 +1820,6 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
* a quiescent state betweentimes.
*/
local_irq_save(flags);
- WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
rdp = this_cpu_ptr(rsp->rda);
/* Add the callback to our list. */