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authorJoel Fernandes (Google) <joel@joelfernandes.org>2019-08-30 12:36:32 -0400
committerPaul E. McKenney <paulmck@kernel.org>2020-01-24 10:24:31 -0800
commit77a40f97030b27b3fc1640a3ed203870f0817f57 (patch)
tree5710fe4b845d8a0cf58e2906e82e1397f9261ecc /kernel/rcu/tiny.c
parente99637becb2e684bee2b9117f817f4d1346b8353 (diff)
rcu: Remove kfree_rcu() special casing and lazy-callback handling
This commit removes kfree_rcu() special-casing and the lazy-callback handling from Tree RCU. It moves some of this special casing to Tiny RCU, the removal of which will be the subject of later commits. This results in a nice negative delta. Suggested-by: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Add slab.h #include, thanks to kbuild test robot <lkp@intel.com>. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tiny.c')
-rw-r--r--kernel/rcu/tiny.c28
1 files changed, 27 insertions, 1 deletions
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 477b4eb44af5..dd572ce7c747 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -22,6 +22,7 @@
#include <linux/time.h>
#include <linux/cpu.h>
#include <linux/prefetch.h>
+#include <linux/slab.h>
#include "rcu.h"
@@ -73,6 +74,31 @@ void rcu_sched_clock_irq(int user)
}
}
+/*
+ * Reclaim the specified callback, either by invoking it for non-kfree cases or
+ * freeing it directly (for kfree). Return true if kfreeing, false otherwise.
+ */
+static inline bool rcu_reclaim_tiny(struct rcu_head *head)
+{
+ rcu_callback_t f;
+ unsigned long offset = (unsigned long)head->func;
+
+ rcu_lock_acquire(&rcu_callback_map);
+ if (__is_kfree_rcu_offset(offset)) {
+ trace_rcu_invoke_kfree_callback("", head, offset);
+ kfree((void *)head - offset);
+ rcu_lock_release(&rcu_callback_map);
+ return true;
+ }
+
+ trace_rcu_invoke_callback("", head);
+ f = head->func;
+ WRITE_ONCE(head->func, (rcu_callback_t)0L);
+ f(head);
+ rcu_lock_release(&rcu_callback_map);
+ return false;
+}
+
/* Invoke the RCU callbacks whose grace period has elapsed. */
static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
{
@@ -100,7 +126,7 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused
prefetch(next);
debug_rcu_head_unqueue(list);
local_bh_disable();
- __rcu_reclaim("", list);
+ rcu_reclaim_tiny(list);
local_bh_enable();
list = next;
}