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Date: Tue, 25 Oct 2022 16:46:12 +0200
From: "Uladzislau Rezki (Sony)" <urezki@...il.com>
To: LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
"Paul E . McKenney" <paulmck@...nel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>,
Neeraj Upadhyay <neeraj.iitr10@...il.com>,
Joel Fernandes <joel@...lfernandes.org>,
Uladzislau Rezki <urezki@...il.com>,
Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: [PATCH 1/1] rcu: Refactor kvfree_call_rcu() and high-level helpers
Currently a kvfree_call_rcu() takes an offset within a
structure as a second parameter, so a helper such as a
kvfree_rcu_arg_2() has to convert rcu_head and a freed
ptr to an offset in order to pass it. That leads to an
extra conversion on macro entry.
Instead of converting, refactor the code in way that a
pointer that has to be freed is passed directly to the
kvfree_call_rcu().
This patch does not make any functional change and is
transparent to all kvfree_rcu() users.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
include/linux/rcupdate.h | 5 ++---
include/linux/rcutiny.h | 12 ++++++------
include/linux/rcutree.h | 2 +-
kernel/rcu/tiny.c | 9 +++------
kernel/rcu/tree.c | 29 ++++++++++++-----------------
5 files changed, 24 insertions(+), 33 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 08605ce7379d..cbd34058fff1 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -985,8 +985,7 @@ do { \
\
if (___p) { \
BUILD_BUG_ON(!__is_kvfree_rcu_offset(offsetof(typeof(*(ptr)), rhf))); \
- kvfree_call_rcu(&((___p)->rhf), (rcu_callback_t)(unsigned long) \
- (offsetof(typeof(*(ptr)), rhf))); \
+ kvfree_call_rcu(&((___p)->rhf), (void *) (___p)); \
} \
} while (0)
@@ -995,7 +994,7 @@ do { \
typeof(ptr) ___p = (ptr); \
\
if (___p) \
- kvfree_call_rcu(NULL, (rcu_callback_t) (___p)); \
+ kvfree_call_rcu(NULL, (void *) (___p)); \
} while (0)
/*
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 768196a5f39d..9623c039964c 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -98,25 +98,25 @@ static inline void synchronize_rcu_expedited(void)
*/
extern void kvfree(const void *addr);
-static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+static inline void __kvfree_call_rcu(struct rcu_head *head, void *ptr)
{
if (head) {
- call_rcu(head, func);
+ call_rcu(head, (rcu_callback_t) ((void *) head - ptr));
return;
}
// kvfree_rcu(one_arg) call.
might_sleep();
synchronize_rcu();
- kvfree((void *) func);
+ kvfree(ptr);
}
#ifdef CONFIG_KASAN_GENERIC
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
+void kvfree_call_rcu(struct rcu_head *head, void *ptr);
#else
-static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+static inline void kvfree_call_rcu(struct rcu_head *head, void *ptr)
{
- __kvfree_call_rcu(head, func);
+ __kvfree_call_rcu(head, ptr);
}
#endif
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 5efb51486e8a..e37a0747a8b2 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -33,7 +33,7 @@ static inline void rcu_virt_note_context_switch(int cpu)
}
void synchronize_rcu_expedited(void);
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
+void kvfree_call_rcu(struct rcu_head *head, void *ptr);
void rcu_barrier(void);
bool rcu_eqs_special_set(int cpu);
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index a33a8d4942c3..6c9496d08669 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -246,15 +246,12 @@ bool poll_state_synchronize_rcu(unsigned long oldstate)
EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu);
#ifdef CONFIG_KASAN_GENERIC
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+void kvfree_call_rcu(struct rcu_head *head, void *ptr)
{
- if (head) {
- void *ptr = (void *) head - (unsigned long) func;
-
+ if (head)
kasan_record_aux_stack_noalloc(ptr);
- }
- __kvfree_call_rcu(head, func);
+ __kvfree_call_rcu(head, ptr);
}
EXPORT_SYMBOL_GPL(kvfree_call_rcu);
#endif
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 0ca21ac0f064..9fea2aff87a1 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3068,8 +3068,8 @@ static void kfree_rcu_work(struct work_struct *work)
* This list is named "Channel 3".
*/
for (; head; head = next) {
- unsigned long offset = (unsigned long)head->func;
- void *ptr = (void *)head - offset;
+ void *ptr = (void *) head->func;
+ unsigned long offset = (void *) head - ptr;
next = head->next;
debug_rcu_head_unqueue((struct rcu_head *)ptr);
@@ -3307,26 +3307,21 @@ add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
* be free'd in workqueue context. This allows us to: batch requests together to
* reduce the number of grace periods during heavy kfree_rcu()/kvfree_rcu() load.
*/
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+void kvfree_call_rcu(struct rcu_head *head, void *ptr)
{
unsigned long flags;
struct kfree_rcu_cpu *krcp;
bool success;
- void *ptr;
- if (head) {
- ptr = (void *) head - (unsigned long) func;
- } else {
- /*
- * Please note there is a limitation for the head-less
- * variant, that is why there is a clear rule for such
- * objects: it can be used from might_sleep() context
- * only. For other places please embed an rcu_head to
- * your data.
- */
+ /*
+ * Please note there is a limitation for the head-less
+ * variant, that is why there is a clear rule for such
+ * objects: it can be used from might_sleep() context
+ * only. For other places please embed an rcu_head to
+ * your data.
+ */
+ if (!head)
might_sleep();
- ptr = (unsigned long *) func;
- }
// Queue the object but don't yet schedule the batch.
if (debug_rcu_head_queue(ptr)) {
@@ -3347,7 +3342,7 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
// Inline if kvfree_rcu(one_arg) call.
goto unlock_return;
- head->func = func;
+ head->func = ptr;
head->next = krcp->head;
krcp->head = head;
success = true;
--
2.30.2
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