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Message-Id: <1509475860-16139-7-git-send-email-longman@redhat.com>
Date: Tue, 31 Oct 2017 14:51:00 -0400
From: Waiman Long <longman@...hat.com>
To: Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.com>,
Jeff Layton <jlayton@...chiereds.net>,
"J. Bruce Fields" <bfields@...ldses.org>,
Tejun Heo <tj@...nel.org>,
Christoph Lameter <cl@...ux-foundation.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Andi Kleen <andi@...stfloor.org>,
Dave Chinner <dchinner@...hat.com>,
Boqun Feng <boqun.feng@...il.com>,
Davidlohr Bueso <dave@...olabs.net>,
Waiman Long <longman@...hat.com>
Subject: [PATCH v8 6/6] lib/dlock-list: Add an IRQ-safe mode to be used in interrupt handler
To enable the use of dlock-list in an interrupt handler, a new
irqsafe mode can now be specified at dlock-list allocation time as
an additional argument to alloc_dlock_list_heads(). With that mode
specified, the spin_lock_irqsave/spin_unlock_irqrestore pair will be
used instead of the regular lock and unlock calls.
Signed-off-by: Waiman Long <longman@...hat.com>
---
fs/super.c | 2 +-
include/linux/dlock-list.h | 22 +++++++++++++++++-----
lib/dlock-list.c | 46 ++++++++++++++++++++++++++++++++--------------
3 files changed, 50 insertions(+), 20 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index a90a070..0840e54 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -214,7 +214,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
INIT_LIST_HEAD(&s->s_inodes_wb);
spin_lock_init(&s->s_inode_wblist_lock);
- if (alloc_dlock_list_heads(&s->s_inodes))
+ if (alloc_dlock_list_heads(&s->s_inodes, false))
goto fail;
if (list_lru_init_memcg(&s->s_dentry_lru))
goto fail;
diff --git a/include/linux/dlock-list.h b/include/linux/dlock-list.h
index b374101..fcb2b71 100644
--- a/include/linux/dlock-list.h
+++ b/include/linux/dlock-list.h
@@ -32,6 +32,8 @@
struct dlock_list_head {
struct list_head list;
spinlock_t lock;
+ int irqsafe; /* IRQ safe mode */
+ unsigned long flags;
} ____cacheline_aligned_in_smp;
struct dlock_list_heads {
@@ -89,7 +91,12 @@ static inline void init_dlock_list_node(struct dlock_list_node *node)
*/
static inline void dlock_list_unlock(struct dlock_list_iter *iter)
{
- spin_unlock(&iter->entry->lock);
+ struct dlock_list_head *h = iter->entry;
+
+ if (h->irqsafe)
+ spin_unlock_irqrestore(&h->lock, h->flags);
+ else
+ spin_unlock(&h->lock);
}
/**
@@ -98,14 +105,19 @@ static inline void dlock_list_unlock(struct dlock_list_iter *iter)
*/
static inline void dlock_list_relock(struct dlock_list_iter *iter)
{
- spin_lock(&iter->entry->lock);
+ struct dlock_list_head *h = iter->entry;
+
+ if (h->irqsafe)
+ spin_lock_irqsave(&h->lock, h->flags);
+ else
+ spin_lock(&h->lock);
}
/*
* Allocation and freeing of dlock list
*/
extern int __alloc_dlock_list_heads(struct dlock_list_heads *dlist,
- struct lock_class_key *key);
+ int irqsafe, struct lock_class_key *key);
extern void free_dlock_list_heads(struct dlock_list_heads *dlist);
/**
@@ -113,10 +125,10 @@ extern int __alloc_dlock_list_heads(struct dlock_list_heads *dlist,
* @dlist : Pointer to the dlock_list_heads structure to be initialized
* Return : 0 if successful, -ENOMEM if memory allocation error
*/
-#define alloc_dlock_list_heads(dlist) \
+#define alloc_dlock_list_heads(dlist, irqsafe) \
({ \
static struct lock_class_key _key; \
- __alloc_dlock_list_heads(dlist, &_key); \
+ __alloc_dlock_list_heads(dlist, irqsafe, &_key); \
})
/*
diff --git a/lib/dlock-list.c b/lib/dlock-list.c
index f3667aa..c1197f5 100644
--- a/lib/dlock-list.c
+++ b/lib/dlock-list.c
@@ -91,8 +91,9 @@ static int __init cpu2idx_init(void)
/**
* __alloc_dlock_list_heads - Initialize and allocate the list of head entries
- * @dlist: Pointer to the dlock_list_heads structure to be initialized
- * @key : The lock class key to be used for lockdep
+ * @dlist : Pointer to the dlock_list_heads structure to be initialized
+ * @irqsafe: IRQ safe mode flag
+ * @key : The lock class key to be used for lockdep
* Return: 0 if successful, -ENOMEM if memory allocation error
*
* This function does not allocate the dlock_list_heads structure itself. The
@@ -108,7 +109,7 @@ static int __init cpu2idx_init(void)
* The extra lists will not be ever used as all the cpu2idx entries will be
* 0 before initialization.
*/
-int __alloc_dlock_list_heads(struct dlock_list_heads *dlist,
+int __alloc_dlock_list_heads(struct dlock_list_heads *dlist, int irqsafe,
struct lock_class_key *key)
{
int idx, cnt = nr_dlock_lists ? nr_dlock_lists : nr_cpu_ids;
@@ -123,6 +124,7 @@ int __alloc_dlock_list_heads(struct dlock_list_heads *dlist,
INIT_LIST_HEAD(&head->list);
head->lock = __SPIN_LOCK_UNLOCKED(&head->lock);
+ head->irqsafe = irqsafe;
lockdep_set_class(&head->lock, key);
}
return 0;
@@ -198,13 +200,19 @@ struct dlock_list_head *dlock_list_hash(struct dlock_list_heads *dlist,
void dlock_list_add(struct dlock_list_node *node,
struct dlock_list_head *head)
{
- /*
- * There is no need to disable preemption
- */
- spin_lock(&head->lock);
- node->head = head;
- list_add(&node->list, &head->list);
- spin_unlock(&head->lock);
+ unsigned long flags;
+
+ if (head->irqsafe) {
+ spin_lock_irqsave(&head->lock, flags);
+ node->head = head;
+ list_add(&node->list, &head->list);
+ spin_unlock_irqrestore(&head->lock, flags);
+ } else {
+ spin_lock(&head->lock);
+ node->head = head;
+ list_add(&node->list, &head->list);
+ spin_unlock(&head->lock);
+ }
}
EXPORT_SYMBOL(dlock_list_add);
@@ -238,6 +246,7 @@ void dlock_lists_add(struct dlock_list_node *node,
void dlock_lists_del(struct dlock_list_node *node)
{
struct dlock_list_head *head;
+ unsigned long flags = 0;
bool retry;
do {
@@ -246,7 +255,11 @@ void dlock_lists_del(struct dlock_list_node *node)
__func__, (unsigned long)node))
return;
- spin_lock(&head->lock);
+ if (head->irqsafe)
+ spin_lock_irqsave(&head->lock, flags);
+ else
+ spin_lock(&head->lock);
+
if (likely(head == node->head)) {
list_del_init(&node->list);
node->head = NULL;
@@ -259,7 +272,11 @@ void dlock_lists_del(struct dlock_list_node *node)
*/
retry = (node->head != NULL);
}
- spin_unlock(&head->lock);
+
+ if (head->irqsafe)
+ spin_unlock_irqrestore(&head->lock, flags);
+ else
+ spin_unlock(&head->lock);
} while (retry);
}
EXPORT_SYMBOL(dlock_lists_del);
@@ -282,7 +299,7 @@ struct dlock_list_node *__dlock_list_next_list(struct dlock_list_iter *iter)
restart:
if (iter->entry) {
- spin_unlock(&iter->entry->lock);
+ dlock_list_unlock(iter);
iter->entry = NULL;
}
@@ -297,7 +314,8 @@ struct dlock_list_node *__dlock_list_next_list(struct dlock_list_iter *iter)
goto next_list;
head = iter->entry = &iter->head[iter->index];
- spin_lock(&head->lock);
+ dlock_list_relock(iter);
+
/*
* There is a slight chance that the list may become empty just
* before the lock is acquired. So an additional check is
--
1.8.3.1
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