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Subject[PATCH 1/2] rcu: Transform kfree_rcu() into kvfree_rcu()
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Recent times kvmalloc() begun widely be used in kernel.
Some of such memory allocations have to be freed after
rcu grace period, and this patch introduces a generic
primitive for doing this.

Currently, there is kfree_rcu() primitive in kernel,
which encodes rcu_head offset inside freed structure
on place of callback function. We can simply reuse it
and replace final kfree() in __rcu_reclaim() with
kvfree(). Since this primitive is able to free memory
allocated via kmalloc(), vmalloc() and kvmalloc(),
we may have single kvfree_rcu(), and define kfree_rcu()
and vfree_rcu() through it.

This allows users to avoid to implement custom functions
for destruction kvmalloc()'ed and vmalloc()'ed memory.
The new primitive kvfree_rcu() are used since next patch.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
include/linux/rcupdate.h | 31 +++++++++++++++++--------------
include/linux/rcutiny.h | 4 ++--
include/linux/rcutree.h | 2 +-
include/trace/events/rcu.h | 12 ++++++------
kernel/rcu/rcu.h | 8 ++++----
kernel/rcu/tree.c | 14 +++++++-------
kernel/rcu/tree_plugin.h | 10 +++++-----
7 files changed, 42 insertions(+), 39 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 043d04784675..22d4086f50b2 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -832,36 +832,36 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)

/*
* Does the specified offset indicate that the corresponding rcu_head
- * structure can be handled by kfree_rcu()?
+ * structure can be handled by kvfree_rcu()?
*/
-#define __is_kfree_rcu_offset(offset) ((offset) < 4096)
+#define __is_kvfree_rcu_offset(offset) ((offset) < 4096)

/*
- * Helper macro for kfree_rcu() to prevent argument-expansion eyestrain.
+ * Helper macro for kvfree_rcu() to prevent argument-expansion eyestrain.
*/
-#define __kfree_rcu(head, offset) \
+#define __kvfree_rcu(head, offset) \
do { \
- BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \
- kfree_call_rcu(head, (rcu_callback_t)(unsigned long)(offset)); \
+ BUILD_BUG_ON(!__is_kvfree_rcu_offset(offset)); \
+ kvfree_call_rcu(head, (rcu_callback_t)(unsigned long)(offset)); \
} while (0)

/**
- * kfree_rcu() - kfree an object after a grace period.
- * @ptr: pointer to kfree
+ * kvfree_rcu() - kvfree an object after a grace period.
+ * @ptr: pointer to kvfree
* @rcu_head: the name of the struct rcu_head within the type of @ptr.
*
- * Many rcu callbacks functions just call kfree() on the base structure.
+ * Many rcu callbacks functions just call kvfree() on the base structure.
* These functions are trivial, but their size adds up, and furthermore
* when they are used in a kernel module, that module must invoke the
* high-latency rcu_barrier() function at module-unload time.
*
- * The kfree_rcu() function handles this issue. Rather than encoding a
- * function address in the embedded rcu_head structure, kfree_rcu() instead
+ * The kvfree_rcu() function handles this issue. Rather than encoding a
+ * function address in the embedded rcu_head structure, kvfree_rcu() instead
* encodes the offset of the rcu_head structure within the base structure.
* Because the functions are not allowed in the low-order 4096 bytes of
* kernel virtual memory, offsets up to 4095 bytes can be accommodated.
* If the offset is larger than 4095 bytes, a compile-time error will
- * be generated in __kfree_rcu(). If this error is triggered, you can
+ * be generated in __kvfree_rcu(). If this error is triggered, you can
* either fall back to use of call_rcu() or rearrange the structure to
* position the rcu_head structure into the first 4096 bytes.
*
@@ -871,9 +871,12 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
* The BUILD_BUG_ON check must not involve any function calls, hence the
* checks are done in macros here.
*/
-#define kfree_rcu(ptr, rcu_head) \
- __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))
+#define kvfree_rcu(ptr, rcu_head) \
+ __kvfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))

+#define kfree_rcu(ptr, rcu_head) kvfree_rcu(ptr, rcu_head)
+
+#define vfree_rcu(ptr, rcu_head) kvfree_rcu(ptr, rcu_head)

/*
* Place this after a lock-acquisition primitive to guarantee that
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index ce9beec35e34..2e484aaa534f 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -84,8 +84,8 @@ static inline void synchronize_sched_expedited(void)
synchronize_sched();
}

-static inline void kfree_call_rcu(struct rcu_head *head,
- rcu_callback_t func)
+static inline void kvfree_call_rcu(struct rcu_head *head,
+ rcu_callback_t func)
{
call_rcu(head, func);
}
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index fd996cdf1833..4d6365be4504 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -48,7 +48,7 @@ void synchronize_rcu_bh(void);
void synchronize_sched_expedited(void);
void synchronize_rcu_expedited(void);

-void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
+void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);

/**
* synchronize_rcu_bh_expedited - Brute-force RCU-bh grace period
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 0b50fda80db0..9507264fa8f8 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -496,13 +496,13 @@ TRACE_EVENT(rcu_callback,

/*
* Tracepoint for the registration of a single RCU callback of the special
- * kfree() form. The first argument is the RCU type, the second argument
+ * kvfree() form. The first argument is the RCU type, the second argument
* is a pointer to the RCU callback, the third argument is the offset
* of the callback within the enclosing RCU-protected data structure,
* the fourth argument is the number of lazy callbacks queued, and the
* fifth argument is the total number of callbacks queued.
*/
-TRACE_EVENT(rcu_kfree_callback,
+TRACE_EVENT(rcu_kvfree_callback,

TP_PROTO(const char *rcuname, struct rcu_head *rhp, unsigned long offset,
long qlen_lazy, long qlen),
@@ -591,12 +591,12 @@ TRACE_EVENT(rcu_invoke_callback,

/*
* Tracepoint for the invocation of a single RCU callback of the special
- * kfree() form. The first argument is the RCU flavor, the second
+ * kvfree() form. The first argument is the RCU flavor, the second
* argument is a pointer to the RCU callback, and the third argument
* is the offset of the callback within the enclosing RCU-protected
* data structure.
*/
-TRACE_EVENT(rcu_invoke_kfree_callback,
+TRACE_EVENT(rcu_invoke_kvfree_callback,

TP_PROTO(const char *rcuname, struct rcu_head *rhp, unsigned long offset),

@@ -767,12 +767,12 @@ TRACE_EVENT(rcu_barrier,
#define trace_rcu_fqs(rcuname, gpnum, cpu, qsevent) do { } while (0)
#define trace_rcu_dyntick(polarity, oldnesting, newnesting, dyntick) do { } while (0)
#define trace_rcu_callback(rcuname, rhp, qlen_lazy, qlen) do { } while (0)
-#define trace_rcu_kfree_callback(rcuname, rhp, offset, qlen_lazy, qlen) \
+#define trace_rcu_kvfree_callback(rcuname, rhp, offset, qlen_lazy, qlen) \
do { } while (0)
#define trace_rcu_batch_start(rcuname, qlen_lazy, qlen, blimit) \
do { } while (0)
#define trace_rcu_invoke_callback(rcuname, rhp) do { } while (0)
-#define trace_rcu_invoke_kfree_callback(rcuname, rhp, offset) do { } while (0)
+#define trace_rcu_invoke_kvfree_callback(rcuname, rhp, offset) do { } while (0)
#define trace_rcu_batch_end(rcuname, callbacks_invoked, cb, nr, iit, risk) \
do { } while (0)
#define trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 6334f2c1abd0..696200886098 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -151,7 +151,7 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
}
#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */

-void kfree(const void *);
+void kvfree(const void *);

/*
* Reclaim the specified callback, either by invoking it (non-lazy case)
@@ -162,9 +162,9 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
unsigned long offset = (unsigned long)head->func;

rcu_lock_acquire(&rcu_callback_map);
- if (__is_kfree_rcu_offset(offset)) {
- RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset);)
- kfree((void *)head - offset);
+ if (__is_kvfree_rcu_offset(offset)) {
+ RCU_TRACE(trace_rcu_invoke_kvfree_callback(rn, head, offset);)
+ kvfree((void *)head - offset);
rcu_lock_release(&rcu_callback_map);
return true;
} else {
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 491bdf39f276..8e736aa11a46 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3061,10 +3061,10 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func,
if (!lazy)
rcu_idle_count_callbacks_posted();

- if (__is_kfree_rcu_offset((unsigned long)func))
- trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func,
- rcu_segcblist_n_lazy_cbs(&rdp->cblist),
- rcu_segcblist_n_cbs(&rdp->cblist));
+ if (__is_kvfree_rcu_offset((unsigned long)func))
+ trace_rcu_kvfree_callback(rsp->name, head, (unsigned long)func,
+ rcu_segcblist_n_lazy_cbs(&rdp->cblist),
+ rcu_segcblist_n_cbs(&rdp->cblist));
else
trace_rcu_callback(rsp->name, head,
rcu_segcblist_n_lazy_cbs(&rdp->cblist),
@@ -3134,14 +3134,14 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
* This will likely be later named something like "call_rcu_lazy()",
* but this change will require some way of tagging the lazy RCU
* callbacks in the list of pending callbacks. Until then, this
- * function may only be called from __kfree_rcu().
+ * function may only be called from __kvfree_rcu().
*/
-void kfree_call_rcu(struct rcu_head *head,
+void kvfree_call_rcu(struct rcu_head *head,
rcu_callback_t func)
{
__call_rcu(head, func, rcu_state_p, -1, 1);
}
-EXPORT_SYMBOL_GPL(kfree_call_rcu);
+EXPORT_SYMBOL_GPL(kvfree_call_rcu);

/*
* Because a context switch is a grace period for RCU-sched and RCU-bh,
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index fb88a028deec..85715963658e 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1984,11 +1984,11 @@ static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
if (!rcu_is_nocb_cpu(rdp->cpu))
return false;
__call_rcu_nocb_enqueue(rdp, rhp, &rhp->next, 1, lazy, flags);
- if (__is_kfree_rcu_offset((unsigned long)rhp->func))
- trace_rcu_kfree_callback(rdp->rsp->name, rhp,
- (unsigned long)rhp->func,
- -atomic_long_read(&rdp->nocb_q_count_lazy),
- -atomic_long_read(&rdp->nocb_q_count));
+ if (__is_kvfree_rcu_offset((unsigned long)rhp->func))
+ trace_rcu_kvfree_callback(rdp->rsp->name, rhp,
+ (unsigned long)rhp->func,
+ -atomic_long_read(&rdp->nocb_q_count_lazy),
+ -atomic_long_read(&rdp->nocb_q_count));
else
trace_rcu_callback(rdp->rsp->name, rhp,
-atomic_long_read(&rdp->nocb_q_count_lazy),
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