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-rw-r--r--lib/sg_pool.c180
1 files changed, 180 insertions, 0 deletions
diff --git a/lib/sg_pool.c b/lib/sg_pool.c
new file mode 100644
index 0000000000..9bfe60ca3f
--- /dev/null
+++ b/lib/sg_pool.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/init.h>
+#include <linux/scatterlist.h>
+#include <linux/mempool.h>
+#include <linux/slab.h>
+
+#define SG_MEMPOOL_NR ARRAY_SIZE(sg_pools)
+#define SG_MEMPOOL_SIZE 2
+
+struct sg_pool {
+ size_t size;
+ char *name;
+ struct kmem_cache *slab;
+ mempool_t *pool;
+};
+
+#define SP(x) { .size = x, "sgpool-" __stringify(x) }
+#if (SG_CHUNK_SIZE < 32)
+#error SG_CHUNK_SIZE is too small (must be 32 or greater)
+#endif
+static struct sg_pool sg_pools[] = {
+ SP(8),
+ SP(16),
+#if (SG_CHUNK_SIZE > 32)
+ SP(32),
+#if (SG_CHUNK_SIZE > 64)
+ SP(64),
+#if (SG_CHUNK_SIZE > 128)
+ SP(128),
+#if (SG_CHUNK_SIZE > 256)
+#error SG_CHUNK_SIZE is too large (256 MAX)
+#endif
+#endif
+#endif
+#endif
+ SP(SG_CHUNK_SIZE)
+};
+#undef SP
+
+static inline unsigned int sg_pool_index(unsigned short nents)
+{
+ unsigned int index;
+
+ BUG_ON(nents > SG_CHUNK_SIZE);
+
+ if (nents <= 8)
+ index = 0;
+ else
+ index = get_count_order(nents) - 3;
+
+ return index;
+}
+
+static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)
+{
+ struct sg_pool *sgp;
+
+ sgp = sg_pools + sg_pool_index(nents);
+ mempool_free(sgl, sgp->pool);
+}
+
+static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)
+{
+ struct sg_pool *sgp;
+
+ sgp = sg_pools + sg_pool_index(nents);
+ return mempool_alloc(sgp->pool, gfp_mask);
+}
+
+/**
+ * sg_free_table_chained - Free a previously mapped sg table
+ * @table: The sg table header to use
+ * @nents_first_chunk: size of the first_chunk SGL passed to
+ * sg_alloc_table_chained
+ *
+ * Description:
+ * Free an sg table previously allocated and setup with
+ * sg_alloc_table_chained().
+ *
+ * @nents_first_chunk has to be same with that same parameter passed
+ * to sg_alloc_table_chained().
+ *
+ **/
+void sg_free_table_chained(struct sg_table *table,
+ unsigned nents_first_chunk)
+{
+ if (table->orig_nents <= nents_first_chunk)
+ return;
+
+ if (nents_first_chunk == 1)
+ nents_first_chunk = 0;
+
+ __sg_free_table(table, SG_CHUNK_SIZE, nents_first_chunk, sg_pool_free,
+ table->orig_nents);
+}
+EXPORT_SYMBOL_GPL(sg_free_table_chained);
+
+/**
+ * sg_alloc_table_chained - Allocate and chain SGLs in an sg table
+ * @table: The sg table header to use
+ * @nents: Number of entries in sg list
+ * @first_chunk: first SGL
+ * @nents_first_chunk: number of the SGL of @first_chunk
+ *
+ * Description:
+ * Allocate and chain SGLs in an sg table. If @nents@ is larger than
+ * @nents_first_chunk a chained sg table will be setup. @first_chunk is
+ * ignored if nents_first_chunk <= 1 because user expects the SGL points
+ * non-chain SGL.
+ *
+ **/
+int sg_alloc_table_chained(struct sg_table *table, int nents,
+ struct scatterlist *first_chunk, unsigned nents_first_chunk)
+{
+ int ret;
+
+ BUG_ON(!nents);
+
+ if (first_chunk && nents_first_chunk) {
+ if (nents <= nents_first_chunk) {
+ table->nents = table->orig_nents = nents;
+ sg_init_table(table->sgl, nents);
+ return 0;
+ }
+ }
+
+ /* User supposes that the 1st SGL includes real entry */
+ if (nents_first_chunk <= 1) {
+ first_chunk = NULL;
+ nents_first_chunk = 0;
+ }
+
+ ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
+ first_chunk, nents_first_chunk,
+ GFP_ATOMIC, sg_pool_alloc);
+ if (unlikely(ret))
+ sg_free_table_chained(table, nents_first_chunk);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(sg_alloc_table_chained);
+
+static __init int sg_pool_init(void)
+{
+ int i;
+
+ for (i = 0; i < SG_MEMPOOL_NR; i++) {
+ struct sg_pool *sgp = sg_pools + i;
+ int size = sgp->size * sizeof(struct scatterlist);
+
+ sgp->slab = kmem_cache_create(sgp->name, size, 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ if (!sgp->slab) {
+ printk(KERN_ERR "SG_POOL: can't init sg slab %s\n",
+ sgp->name);
+ goto cleanup_sdb;
+ }
+
+ sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
+ sgp->slab);
+ if (!sgp->pool) {
+ printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n",
+ sgp->name);
+ goto cleanup_sdb;
+ }
+ }
+
+ return 0;
+
+cleanup_sdb:
+ for (i = 0; i < SG_MEMPOOL_NR; i++) {
+ struct sg_pool *sgp = sg_pools + i;
+
+ mempool_destroy(sgp->pool);
+ kmem_cache_destroy(sgp->slab);
+ }
+
+ return -ENOMEM;
+}
+
+subsys_initcall(sg_pool_init);