From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
To: linux-kernel@vger.kernel.org
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>,
Josh Triplett <josh@joshtriplett.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
linux-mm@kvack.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
rcu@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 15/18] rcu: Support headless variant in the kvfree_rcu()
Date: Sun, 29 Mar 2020 22:32:45 -0400 [thread overview]
Message-ID: <20200330023248.164994-16-joel@joelfernandes.org> (raw)
In-Reply-To: <20200330023248.164994-1-joel@joelfernandes.org>
From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Make it possible to pass one or two arguments to the
kvfree_rcu() macro what corresponds to either headless
case or not, so it becomes a bit versatile.
As a result we obtain two ways of using that macro,
below are two examples:
a) kvfree_rcu(ptr, rhf);
struct X {
struct rcu_head rhf;
unsigned char data[100];
};
void *ptr = kvmalloc(sizeof(struct X), GFP_KERNEL);
if (ptr)
kvfree_rcu(ptr, rhf);
b) kvfree_rcu(ptr);
void *ptr = kvmalloc(some_bytes, GFP_KERNEL);
if (ptr)
kvfree_rcu(ptr);
Last one, we name it headless variant, only needs one
argument, means it does not require any rcu_head to be
present within the type of ptr.
There is a restriction the (b) context has to fall into
might_sleep() annotation. To check that, please activate
the CONFIG_DEBUG_ATOMIC_SLEEP option in your kernel.
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
include/linux/rcupdate.h | 38 ++++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index edb6eeba49f83..7d04bbeeeef14 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -872,12 +872,42 @@ do { \
/**
* kvfree_rcu() - kvfree an object after a grace period.
- * @ptr: pointer to kvfree
- * @rhf: the name of the struct rcu_head within the type of @ptr.
*
- * Same as kfree_rcu(), just simple alias.
+ * This macro consists of one or two arguments and it is
+ * based on whether an object is head-less or not. If it
+ * has a head then a semantic stays the same as it used
+ * to be before:
+ *
+ * kvfree_rcu(ptr, rhf);
+ *
+ * where @ptr is a pointer to kvfree(), @rhf is the name
+ * of the rcu_head structure within the type of @ptr.
+ *
+ * When it comes to head-less variant, only one argument
+ * is passed and that is just a pointer which has to be
+ * freed after a grace period. Therefore the semantic is
+ *
+ * kvfree_rcu(ptr);
+ *
+ * where @ptr is a pointer to kvfree().
+ *
+ * Please note, head-less way of freeing is permitted to
+ * use from a context that has to follow might_sleep()
+ * annotation. Otherwise, please switch and embed the
+ * rcu_head structure within the type of @ptr.
*/
-#define kvfree_rcu(ptr, rhf) kfree_rcu(ptr, rhf)
+#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__, \
+ kvfree_rcu_arg_2, kvfree_rcu_arg_1)(__VA_ARGS__)
+
+#define KVFREE_GET_MACRO(_1, _2, NAME, ...) NAME
+#define kvfree_rcu_arg_2(ptr, rhf) kfree_rcu(ptr, rhf)
+#define kvfree_rcu_arg_1(ptr) \
+do { \
+ typeof(ptr) ___p = (ptr); \
+ \
+ if (___p) \
+ kvfree_call_rcu(NULL, (rcu_callback_t) (___p)); \
+} while (0)
/*
* Place this after a lock-acquisition primitive to guarantee that
--
2.26.0.rc2.310.g2932bb562d-goog
next prev parent reply other threads:[~2020-03-30 2:34 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-30 2:32 [PATCH 00/18] kfree_rcu() improvements for -rcu dev Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 01/18] mm/list_lru.c: Rename kvfree_rcu() to local variant Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 02/18] rcu: Introduce kvfree_rcu() interface Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 03/18] rcu: Rename rcu_invoke_kfree_callback/rcu_kfree_callback Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 04/18] rcu: Rename __is_kfree_rcu_offset() macro Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 05/18] rcu: Rename kfree_call_rcu() to the kvfree_call_rcu() Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 06/18] mm/list_lru.c: Remove kvfree_rcu_local() function Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 07/18] rcu/tree: Simplify debug_objects handling Joel Fernandes (Google)
2020-03-30 7:00 ` kbuild test robot
2020-03-30 18:42 ` Joel Fernandes
2020-03-30 2:32 ` [PATCH 08/18] rcu/tree: Clarify emergency path comment better Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 09/18] rcu/tree: Simplify KFREE_BULK_MAX_ENTR macro Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 10/18] rcu/tree: Maintain separate array for vmalloc ptrs Joel Fernandes (Google)
2020-03-30 6:48 ` kbuild test robot
2020-03-30 9:10 ` kbuild test robot
2020-03-30 15:29 ` Uladzislau Rezki
2020-03-30 15:31 ` Matthew Wilcox
2020-03-30 15:37 ` Paul E. McKenney
2020-03-30 17:16 ` Joel Fernandes
2020-03-30 17:43 ` Uladzislau Rezki
2020-03-30 18:21 ` Paul E. McKenney
2020-03-30 2:32 ` [PATCH 11/18] rcu/tree: Introduce expedited_drain flag Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 12/18] rcu/tree: Support reclaim for head-less object Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 13/18] rcu/tiny: Move kvfree_call_rcu() out of header Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 14/18] rcu/tiny: Support reclaim for head-less object Joel Fernandes (Google)
2020-03-30 2:32 ` Joel Fernandes (Google) [this message]
2020-03-30 2:32 ` [PATCH 16/18] rcu/tree: Remove extra next variable in kfree worker function Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 17/18] rcu/tree: Simplify is_vmalloc_addr expression Joel Fernandes (Google)
2020-03-30 2:32 ` [PATCH 18/18] rcu/tree: Make kvfree_rcu() tolerate any alignment Joel Fernandes (Google)
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