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Subject[RFC][PATCH 5/6] Slab Prep: Move cache_grow()
Move cache_grow() a few lines further down in mm/slab.c to gain access to a
couple debugging functions that will be used by the next patch. Also,
rename a goto label and fixup a couple comments.

-Matt
Move cache_grow() below some debugging function definitions, so those debugging
functions can be inserted into cache_grow() by the next patch without needing
forward declarations.

Also, do a few small cleanups:
Tidy up a few comments
Rename a label to something readable

Signed-off-by: Matthew Dobson <colpatch@us.ibm.com>

Index: linux-2.6.15-rc5+critical_pool/mm/slab.c
===================================================================
--- linux-2.6.15-rc5+critical_pool.orig/mm/slab.c 2005-12-13 16:08:04.123634776 -0800
+++ linux-2.6.15-rc5+critical_pool/mm/slab.c 2005-12-13 16:14:25.757617592 -0800
@@ -2203,96 +2203,6 @@ static void set_slab_attr(kmem_cache_t *
} while (--i);
}

-/*
- * Grow (by 1) the number of slabs within a cache. This is called by
- * kmem_cache_alloc() when there are no active objs left in a cache.
- */
-static int cache_grow(kmem_cache_t *cachep, gfp_t flags, int nodeid)
-{
- struct slab *slabp;
- void *objp;
- size_t offset;
- gfp_t local_flags;
- unsigned long ctor_flags;
- struct kmem_list3 *l3;
-
- /* Be lazy and only check for valid flags here,
- * keeping it out of the critical path in kmem_cache_alloc().
- */
- if (flags & ~(SLAB_DMA|SLAB_LEVEL_MASK|SLAB_NO_GROW))
- BUG();
- if (flags & SLAB_NO_GROW)
- return 0;
-
- ctor_flags = SLAB_CTOR_CONSTRUCTOR;
- local_flags = (flags & SLAB_LEVEL_MASK);
- if (!(local_flags & __GFP_WAIT))
- /*
- * Not allowed to sleep. Need to tell a constructor about
- * this - it might need to know...
- */
- ctor_flags |= SLAB_CTOR_ATOMIC;
-
- /* About to mess with non-constant members - lock. */
- check_irq_off();
- spin_lock(&cachep->spinlock);
-
- /* Get colour for the slab, and cal the next value. */
- offset = cachep->colour_next;
- cachep->colour_next++;
- if (cachep->colour_next >= cachep->colour)
- cachep->colour_next = 0;
- offset *= cachep->colour_off;
-
- spin_unlock(&cachep->spinlock);
-
- check_irq_off();
- if (local_flags & __GFP_WAIT)
- local_irq_enable();
-
- /*
- * The test for missing atomic flag is performed here, rather than
- * the more obvious place, simply to reduce the critical path length
- * in kmem_cache_alloc(). If a caller is seriously mis-behaving they
- * will eventually be caught here (where it matters).
- */
- kmem_flagcheck(cachep, flags);
-
- /* Get mem for the objs.
- * Attempt to allocate a physical page from 'nodeid',
- */
- if (!(objp = kmem_getpages(cachep, flags, nodeid)))
- goto failed;
-
- /* Get slab management. */
- if (!(slabp = alloc_slabmgmt(cachep, objp, offset, local_flags)))
- goto opps1;
-
- slabp->nodeid = nodeid;
- set_slab_attr(cachep, slabp, objp);
-
- cache_init_objs(cachep, slabp, ctor_flags);
-
- if (local_flags & __GFP_WAIT)
- local_irq_disable();
- check_irq_off();
- l3 = cachep->nodelists[nodeid];
- spin_lock(&l3->list_lock);
-
- /* Make slab active. */
- list_add_tail(&slabp->list, &(l3->slabs_free));
- STATS_INC_GROWN(cachep);
- l3->free_objects += cachep->num;
- spin_unlock(&l3->list_lock);
- return 1;
-opps1:
- kmem_freepages(cachep, objp);
-failed:
- if (local_flags & __GFP_WAIT)
- local_irq_disable();
- return 0;
-}
-
#if DEBUG

/*
@@ -2414,6 +2324,90 @@ bad:
#define check_slabp(x,y) do { } while(0)
#endif

+/**
+ * Grow (by 1) the number of slabs within a cache. This is called by
+ * kmem_cache_alloc() when there are no active objs left in a cache.
+ */
+static int cache_grow(kmem_cache_t *cachep, gfp_t flags, int nodeid)
+{
+ struct slab *slabp;
+ void *objp;
+ size_t offset;
+ gfp_t local_flags;
+ unsigned long ctor_flags;
+ struct kmem_list3 *l3;
+
+ /*
+ * Be lazy and only check for valid flags here,
+ * keeping it out of the critical path in kmem_cache_alloc().
+ */
+ if (flags & ~(SLAB_DMA|SLAB_LEVEL_MASK|SLAB_NO_GROW))
+ BUG();
+ if (flags & SLAB_NO_GROW)
+ return 0;
+
+ ctor_flags = SLAB_CTOR_CONSTRUCTOR;
+ local_flags = (flags & SLAB_LEVEL_MASK);
+ if (!(local_flags & __GFP_WAIT))
+ /* The constructor might need to know it can't sleep */
+ ctor_flags |= SLAB_CTOR_ATOMIC;
+
+ /* About to mess with non-constant members - lock. */
+ check_irq_off();
+ spin_lock(&cachep->spinlock);
+ /* Get colour for the slab, and calculate the next value. */
+ offset = cachep->colour_next;
+ cachep->colour_next++;
+ if (cachep->colour_next >= cachep->colour)
+ cachep->colour_next = 0;
+ offset *= cachep->colour_off;
+ /* done... Unlock. */
+ spin_unlock(&cachep->spinlock);
+
+ check_irq_off();
+ if (local_flags & __GFP_WAIT)
+ local_irq_enable();
+
+ /*
+ * Ensure caller isn't asking for DMA memory if the slab wasn't created
+ * with the SLAB_DMA flag.
+ * Also ensure the caller *is* asking for DMA memory if the slab was
+ * created with the SLAB_DMA flag.
+ */
+ kmem_flagcheck(cachep, flags);
+
+ /* Get memory for the objects by allocating a page from 'nodeid'. */
+ if (!(objp = kmem_getpages(cachep, flags, nodeid)))
+ goto failed;
+
+ /* Get slab management. */
+ if (!(slabp = alloc_slabmgmt(cachep, objp, offset, local_flags)))
+ goto failed_freepages;
+
+ slabp->nodeid = nodeid;
+ set_slab_attr(cachep, slabp, objp);
+ cache_init_objs(cachep, slabp, ctor_flags);
+
+ if (local_flags & __GFP_WAIT)
+ local_irq_disable();
+ check_irq_off();
+ l3 = cachep->nodelists[nodeid];
+ spin_lock(&l3->list_lock);
+
+ /* Make slab active. */
+ list_add_tail(&slabp->list, &(l3->slabs_free));
+ STATS_INC_GROWN(cachep);
+ l3->free_objects += cachep->num;
+ spin_unlock(&l3->list_lock);
+ return 1;
+failed_freepages:
+ kmem_freepages(cachep, objp);
+failed:
+ if (local_flags & __GFP_WAIT)
+ local_irq_disable();
+ return 0;
+}
+
static void *cache_alloc_refill(kmem_cache_t *cachep, gfp_t flags)
{
int batchcount;
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