[PATCH v2 5/5] lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c
From: Ming Lin
Date: Tue Mar 22 2016 - 18:04:44 EST
From: Ming Lin <ming.l@xxxxxxxxxxxxxxx>
Now it's ready to move the mempool based SG chained allocator code from
SCSI driver to lib/sg_pool.c, which will be compiled only based on a Kconfig
symbol CONFIG_SG_POOL.
SCSI selects CONFIG_SG_POOL.
Signed-off-by: Ming Lin <ming.l@xxxxxxxxxxxxxxx>
---
drivers/scsi/Kconfig | 1 +
drivers/scsi/scsi_lib.c | 137 -----------------------------------
include/linux/scatterlist.h | 25 +++++++
include/scsi/scsi.h | 19 -----
lib/Kconfig | 7 ++
lib/Makefile | 1 +
lib/sg_pool.c | 172 ++++++++++++++++++++++++++++++++++++++++++++
7 files changed, 206 insertions(+), 156 deletions(-)
create mode 100644 lib/sg_pool.c
diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index e2f31c9..ee9cf41 100644
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -17,6 +17,7 @@ config SCSI
tristate "SCSI device support"
depends on BLOCK
select SCSI_DMA if HAS_DMA
+ select SG_POOL
---help---
If you want to use a SCSI hard disk, SCSI tape drive, SCSI CD-ROM or
any other SCSI device under Linux, say Y and make sure that you know
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 478b0e8..6d818e8 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -14,8 +14,6 @@
#include <linux/completion.h>
#include <linux/kernel.h>
#include <linux/export.h>
-#include <linux/mempool.h>
-#include <linux/slab.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/delay.h>
@@ -40,39 +38,6 @@
#include "scsi_logging.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
-
struct kmem_cache *scsi_sdb_cache;
/*
@@ -553,65 +518,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
scsi_run_queue(sdev->request_queue);
}
-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);
-}
-
-static void sg_free_table_chained(struct sg_table *table, bool first_chunk)
-{
- if (first_chunk && table->orig_nents <= SG_CHUNK_SIZE)
- return;
- __sg_free_table(table, SG_CHUNK_SIZE, first_chunk, sg_pool_free);
-}
-
-static int sg_alloc_table_chained(struct sg_table *table, int nents,
- struct scatterlist *first_chunk)
-{
- int ret;
-
- BUG_ON(!nents);
-
- if (first_chunk) {
- if (nents <= SG_CHUNK_SIZE) {
- table->nents = table->orig_nents = nents;
- sg_init_table(table->sgl, nents);
- return 0;
- }
- }
-
- ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
- first_chunk, GFP_ATOMIC, sg_pool_alloc);
- if (unlikely(ret))
- sg_free_table_chained(table, (bool)first_chunk);
- return ret;
-}
-
static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
{
if (cmd->request->cmd_type == REQ_TYPE_FS) {
@@ -2269,8 +2175,6 @@ EXPORT_SYMBOL(scsi_unblock_requests);
int __init scsi_init_queue(void)
{
- int i;
-
scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
sizeof(struct scsi_data_buffer),
0, 0, NULL);
@@ -2279,53 +2183,12 @@ int __init scsi_init_queue(void)
return -ENOMEM;
}
- 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 "SCSI: 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 "SCSI: 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;
- if (sgp->pool)
- mempool_destroy(sgp->pool);
- if (sgp->slab)
- kmem_cache_destroy(sgp->slab);
- }
- kmem_cache_destroy(scsi_sdb_cache);
-
- return -ENOMEM;
}
void scsi_exit_queue(void)
{
- int i;
-
kmem_cache_destroy(scsi_sdb_cache);
-
- for (i = 0; i < SG_MEMPOOL_NR; i++) {
- struct sg_pool *sgp = sg_pools + i;
- mempool_destroy(sgp->pool);
- kmem_cache_destroy(sgp->slab);
- }
}
/**
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 556ec1e..cb3c8fe 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -286,6 +286,31 @@ size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
/*
+ * The maximum number of SG segments that we will put inside a
+ * scatterlist (unless chaining is used). Should ideally fit inside a
+ * single page, to avoid a higher order allocation. We could define this
+ * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
+ * minimum value is 32
+ */
+#define SG_CHUNK_SIZE 128
+
+/*
+ * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
+ * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
+ */
+#ifdef CONFIG_ARCH_HAS_SG_CHAIN
+#define SG_MAX_SEGMENTS 2048
+#else
+#define SG_MAX_SEGMENTS SG_CHUNK_SIZE
+#endif
+
+#ifdef CONFIG_SG_POOL
+void sg_free_table_chained(struct sg_table *table, bool first_chunk);
+int sg_alloc_table_chained(struct sg_table *table, int nents,
+ struct scatterlist *first_chunk);
+#endif
+
+/*
* sg page iterator
*
* Iterates over sg entries page-by-page. On each successful iteration,
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 74dafa7..8ec7c30 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -18,25 +18,6 @@ enum scsi_timeouts {
};
/*
- * The maximum number of SG segments that we will put inside a
- * scatterlist (unless chaining is used). Should ideally fit inside a
- * single page, to avoid a higher order allocation. We could define this
- * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
- * minimum value is 32
- */
-#define SG_CHUNK_SIZE 128
-
-/*
- * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
- * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
- */
-#ifdef CONFIG_ARCH_HAS_SG_CHAIN
-#define SG_MAX_SEGMENTS 2048
-#else
-#define SG_MAX_SEGMENTS SG_CHUNK_SIZE
-#endif
-
-/*
* DIX-capable adapters effectively support infinite chaining for the
* protection information scatterlist
*/
diff --git a/lib/Kconfig b/lib/Kconfig
index 133ebc0..3ee40b2 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -523,6 +523,13 @@ config SG_SPLIT
a scatterlist. This should be selected by a driver or an API which
whishes to split a scatterlist amongst multiple DMA channels.
+config SG_POOL
+ def_bool n
+ help
+ Provides a helper to allocate chained scatterlists. This should be
+ selected by a driver or an API which whishes to allocate chained
+ scatterlist.
+
#
# sg chaining option
#
diff --git a/lib/Makefile b/lib/Makefile
index a7c26a4..377876e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -164,6 +164,7 @@ obj-$(CONFIG_GENERIC_STRNLEN_USER) += strnlen_user.o
obj-$(CONFIG_GENERIC_NET_UTILS) += net_utils.o
obj-$(CONFIG_SG_SPLIT) += sg_split.o
+obj-$(CONFIG_SG_POOL) += sg_pool.o
obj-$(CONFIG_STMP_DEVICE) += stmp_device.o
obj-$(CONFIG_IRQ_POLL) += irq_poll.o
diff --git a/lib/sg_pool.c b/lib/sg_pool.c
new file mode 100644
index 0000000..6dd3061
--- /dev/null
+++ b/lib/sg_pool.c
@@ -0,0 +1,172 @@
+#include <linux/module.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
+ * @first_chunk: was first_chunk not NULL in sg_alloc_table_chained?
+ *
+ * Description:
+ * Free an sg table previously allocated and setup with
+ * sg_alloc_table_chained().
+ *
+ **/
+void sg_free_table_chained(struct sg_table *table, bool first_chunk)
+{
+ if (first_chunk && table->orig_nents <= SG_CHUNK_SIZE)
+ return;
+ __sg_free_table(table, SG_CHUNK_SIZE, first_chunk, sg_pool_free);
+}
+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
+ *
+ * Description:
+ * Allocate and chain SGLs in an sg table. If @nents@ is larger than
+ * SG_CHUNK_SIZE a chained sg table will be setup.
+ *
+ **/
+int sg_alloc_table_chained(struct sg_table *table, int nents,
+ struct scatterlist *first_chunk)
+{
+ int ret;
+
+ BUG_ON(!nents);
+
+ if (first_chunk) {
+ if (nents <= SG_CHUNK_SIZE) {
+ table->nents = table->orig_nents = nents;
+ sg_init_table(table->sgl, nents);
+ return 0;
+ }
+ }
+
+ ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
+ first_chunk, GFP_ATOMIC, sg_pool_alloc);
+ if (unlikely(ret))
+ sg_free_table_chained(table, (bool)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;
+ if (sgp->pool)
+ mempool_destroy(sgp->pool);
+ if (sgp->slab)
+ kmem_cache_destroy(sgp->slab);
+ }
+
+ return -ENOMEM;
+}
+
+static __exit void sg_pool_exit(void)
+{
+ int i;
+
+ for (i = 0; i < SG_MEMPOOL_NR; i++) {
+ struct sg_pool *sgp = sg_pools + i;
+ mempool_destroy(sgp->pool);
+ kmem_cache_destroy(sgp->slab);
+ }
+}
+
+module_init(sg_pool_init);
+module_exit(sg_pool_exit);
--
1.9.1