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Subject[PATCH 1/8] mempool: factor out mempool_fill()
Date
Factor out mempool_fill() from mempool_create() and mempool_resize().
When called, it fills the reservoir upto the configured min_nr
elements.

After the change, gotos in mempool_resize() exit paths don't make
whole lot of sense, unlock and return directly.

Note that mempool_create() repeatedly locks and unlocks pool->lock
while filling the pool initially and mempool_resize() may go through
one extra locking cycle. This shouldn't result in noticeable
difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
---
mm/mempool.c | 75 ++++++++++++++++++++++++++++++++++++---------------------
1 files changed, 47 insertions(+), 28 deletions(-)

diff --git a/mm/mempool.c b/mm/mempool.c
index d904981..e0403d0 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -47,6 +47,43 @@ void mempool_destroy(mempool_t *pool)
EXPORT_SYMBOL(mempool_destroy);

/**
+ * mempool_fill - fill a memory pool
+ * @pool: memory pool to fill
+ * @gfp_mask: allocation mask to use
+ *
+ * Allocate new elements with @gfp_mask and fill @pool so that it has
+ * @pool->min_nr elements. Returns 0 on success, -errno on failure.
+ */
+static int mempool_fill(mempool_t *pool, gfp_t gfp_mask)
+{
+ /*
+ * If curr_nr == min_nr is visible, we're correct regardless of
+ * locking.
+ */
+ while (pool->curr_nr < pool->min_nr) {
+ void *elem;
+ unsigned long flags;
+
+ elem = pool->alloc(gfp_mask, pool->pool_data);
+ if (unlikely(!elem))
+ return -ENOMEM;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ if (pool->curr_nr < pool->min_nr) {
+ add_element(pool, elem);
+ elem = NULL;
+ }
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ if (elem) {
+ pool->free(elem, pool->pool_data);
+ return 0;
+ }
+ }
+ return 0;
+}
+
+/**
* mempool_create - create a memory pool
* @min_nr: the minimum number of elements guaranteed to be
* allocated for this pool.
@@ -90,16 +127,11 @@ mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
/*
* First pre-allocate the guaranteed number of buffers.
*/
- while (pool->curr_nr < pool->min_nr) {
- void *element;
-
- element = pool->alloc(GFP_KERNEL, pool->pool_data);
- if (unlikely(!element)) {
- mempool_destroy(pool);
- return NULL;
- }
- add_element(pool, element);
+ if (mempool_fill(pool, GFP_KERNEL)) {
+ mempool_destroy(pool);
+ return NULL;
}
+
return pool;
}
EXPORT_SYMBOL(mempool_create_node);
@@ -137,7 +169,8 @@ int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
spin_lock_irqsave(&pool->lock, flags);
}
pool->min_nr = new_min_nr;
- goto out_unlock;
+ spin_unlock_irqrestore(&pool->lock, flags);
+ return 0;
}
spin_unlock_irqrestore(&pool->lock, flags);

@@ -151,31 +184,17 @@ int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
/* Raced, other resize will do our work */
spin_unlock_irqrestore(&pool->lock, flags);
kfree(new_elements);
- goto out;
+ return 0;
}
memcpy(new_elements, pool->elements,
pool->curr_nr * sizeof(*new_elements));
kfree(pool->elements);
pool->elements = new_elements;
pool->min_nr = new_min_nr;
-
- while (pool->curr_nr < pool->min_nr) {
- spin_unlock_irqrestore(&pool->lock, flags);
- element = pool->alloc(gfp_mask, pool->pool_data);
- if (!element)
- goto out;
- spin_lock_irqsave(&pool->lock, flags);
- if (pool->curr_nr < pool->min_nr) {
- add_element(pool, element);
- } else {
- spin_unlock_irqrestore(&pool->lock, flags);
- pool->free(element, pool->pool_data); /* Raced */
- goto out;
- }
- }
-out_unlock:
spin_unlock_irqrestore(&pool->lock, flags);
-out:
+
+ mempool_fill(pool, gfp_mask);
+
return 0;
}
EXPORT_SYMBOL(mempool_resize);
--
1.7.7.3


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