[PATCH 0/3] Use sbitmap instead of percpu_ida

[PATCH 0/3] Use sbitmap instead of percpu_ida

[Matthew Wilcox]

Removing the percpu_ida code nets over 400 lines of removal.  It's not
as spectacular as deleting an entire architecture, but it's still a
worthy reduction in lines of code.

Untested due to lack of hardware and not understanding how to set up a
target platform.

Changes from v1:
 - Fixed bugs pointed out by Jens in iscsit_wait_for_tag()
 - Abstracted out tag freeing as requested by Bart
 - Made iscsit_wait_for_tag static as pointed out by 0day

Matthew Wilcox (3):
  target: Abstract tag freeing
  Convert target drivers to use sbitmap
  Remove percpu_ida

 drivers/scsi/qla2xxx/qla_target.c        |  14 +-
 drivers/target/iscsi/iscsi_target_util.c |  35 ++-
 drivers/target/sbp/sbp_target.c          |   7 +-
 drivers/target/target_core_transport.c   |   5 +-
 drivers/target/tcm_fc/tfc_cmd.c          |  10 +-
 drivers/usb/gadget/function/f_tcm.c      |   7 +-
 drivers/vhost/scsi.c                     |   8 +-
 drivers/xen/xen-scsiback.c               |   9 +-
 include/linux/percpu_ida.h               |  83 -----
 include/target/iscsi/iscsi_target_core.h |   1 +
 include/target/target_core_base.h        |  10 +-
 lib/Makefile                             |   2 +-
 lib/percpu_ida.c                         | 370 -----------------------
 13 files changed, 73 insertions(+), 488 deletions(-)
 delete mode 100644 include/linux/percpu_ida.h
 delete mode 100644 lib/percpu_ida.c

-- 
2.17.1

[PATCH 1/3] target: Abstract tag freeing

[Matthew Wilcox]

Introduce target_free_tag() and convert all drivers to use it.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 drivers/scsi/qla2xxx/qla_target.c        | 4 ++--
 drivers/target/iscsi/iscsi_target_util.c | 2 +-
 drivers/target/sbp/sbp_target.c          | 2 +-
 drivers/target/tcm_fc/tfc_cmd.c          | 4 ++--
 drivers/usb/gadget/function/f_tcm.c      | 2 +-
 drivers/vhost/scsi.c                     | 2 +-
 drivers/xen/xen-scsiback.c               | 4 +---
 include/target/target_core_base.h        | 5 +++++
 8 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index b85c833099ff..05290966e630 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -3783,7 +3783,7 @@ void qlt_free_cmd(struct qla_tgt_cmd *cmd)
 		return;
 	}
 	cmd->jiffies_at_free = get_jiffies_64();
-	percpu_ida_free(&sess->se_sess->sess_tag_pool, cmd->se_cmd.map_tag);
+	target_free_tag(sess->se_sess, &cmd->se_cmd);
 }
 EXPORT_SYMBOL(qlt_free_cmd);
 
@@ -4146,7 +4146,7 @@ static void __qlt_do_work(struct qla_tgt_cmd *cmd)
 	qlt_send_term_exchange(qpair, NULL, &cmd->atio, 1, 0);
 
 	qlt_decr_num_pend_cmds(vha);
-	percpu_ida_free(&sess->se_sess->sess_tag_pool, cmd->se_cmd.map_tag);
+	target_free_tag(sess->se_sess, &cmd->se_cmd);
 	spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
 
 	spin_lock_irqsave(&ha->tgt.sess_lock, flags);
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 4435bf374d2d..7e98697cfb8e 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -711,7 +711,7 @@ void iscsit_release_cmd(struct iscsi_cmd *cmd)
 	kfree(cmd->iov_data);
 	kfree(cmd->text_in_ptr);
 
-	percpu_ida_free(&sess->se_sess->sess_tag_pool, se_cmd->map_tag);
+	target_free_tag(sess->se_sess, se_cmd);
 }
 EXPORT_SYMBOL(iscsit_release_cmd);
 
diff --git a/drivers/target/sbp/sbp_target.c b/drivers/target/sbp/sbp_target.c
index fb1003921d85..679ae29d25ab 100644
--- a/drivers/target/sbp/sbp_target.c
+++ b/drivers/target/sbp/sbp_target.c
@@ -1460,7 +1460,7 @@ static void sbp_free_request(struct sbp_target_request *req)
 	kfree(req->pg_tbl);
 	kfree(req->cmd_buf);
 
-	percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
+	target_free_tag(se_sess, se_cmd);
 }
 
 static void sbp_mgt_agent_process(struct work_struct *work)
diff --git a/drivers/target/tcm_fc/tfc_cmd.c b/drivers/target/tcm_fc/tfc_cmd.c
index ec372860106f..13e4efbe1ce7 100644
--- a/drivers/target/tcm_fc/tfc_cmd.c
+++ b/drivers/target/tcm_fc/tfc_cmd.c
@@ -92,7 +92,7 @@ static void ft_free_cmd(struct ft_cmd *cmd)
 	if (fr_seq(fp))
 		fc_seq_release(fr_seq(fp));
 	fc_frame_free(fp);
-	percpu_ida_free(&sess->se_sess->sess_tag_pool, cmd->se_cmd.map_tag);
+	target_free_tag(sess->se_sess, &cmd->se_cmd);
 	ft_sess_put(sess);	/* undo get from lookup at recv */
 }
 
@@ -461,7 +461,7 @@ static void ft_recv_cmd(struct ft_sess *sess, struct fc_frame *fp)
 	cmd->sess = sess;
 	cmd->seq = fc_seq_assign(lport, fp);
 	if (!cmd->seq) {
-		percpu_ida_free(&se_sess->sess_tag_pool, tag);
+		target_free_tag(se_sess, &cmd->se_cmd);
 		goto busy;
 	}
 	cmd->req_frame = fp;		/* hold frame during cmd */
diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index d78dbb73bde8..9f670d9224b9 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -1288,7 +1288,7 @@ static void usbg_release_cmd(struct se_cmd *se_cmd)
 	struct se_session *se_sess = se_cmd->se_sess;
 
 	kfree(cmd->data_buf);
-	percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
+	target_free_tag(se_sess, se_cmd);
 }
 
 static u32 usbg_sess_get_index(struct se_session *se_sess)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 7ad57094d736..70d35e696533 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -324,7 +324,7 @@ static void vhost_scsi_release_cmd(struct se_cmd *se_cmd)
 	}
 
 	vhost_scsi_put_inflight(tv_cmd->inflight);
-	percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
+	target_free_tag(se_sess, se_cmd);
 }
 
 static u32 vhost_scsi_sess_get_index(struct se_session *se_sess)
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 7bc88fd43cfc..ec6635258ed8 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -1377,9 +1377,7 @@ static int scsiback_check_stop_free(struct se_cmd *se_cmd)
 
 static void scsiback_release_cmd(struct se_cmd *se_cmd)
 {
-	struct se_session *se_sess = se_cmd->se_sess;
-
-	percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
+	target_free_tag(se_cmd->se_sess, se_cmd);
 }
 
 static u32 scsiback_sess_get_index(struct se_session *se_sess)
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 922a39f45abc..260c2f3e9460 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -934,4 +934,9 @@ static inline void atomic_dec_mb(atomic_t *v)
 	smp_mb__after_atomic();
 }
 
+static inline void target_free_tag(struct se_session *sess, struct se_cmd *cmd)
+{
+	percpu_ida_free(&sess->sess_tag_pool, cmd->map_tag);
+}
+
 #endif /* TARGET_CORE_BASE_H */
-- 
2.17.1


------------------------------------------------------------------------------
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[PATCH 2/3] Convert target drivers to use sbitmap

[Matthew Wilcox]

The sbitmap and the percpu_ida perform essentially the same task,
allocating tags for commands.  The sbitmap outperforms the percpu_ida
as documented here: https://lkml.org/lkml/2014/4/22/553

The sbitmap interface is a little harder to use, but being able to
remove the percpu_ida code and getting better performance justifies the
additional complexity.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>	# f_tcm
---
 drivers/scsi/qla2xxx/qla_target.c        | 10 ++++---
 drivers/target/iscsi/iscsi_target_util.c | 33 +++++++++++++++++++++---
 drivers/target/sbp/sbp_target.c          |  5 ++--
 drivers/target/target_core_transport.c   |  5 ++--
 drivers/target/tcm_fc/tfc_cmd.c          |  6 ++---
 drivers/usb/gadget/function/f_tcm.c      |  5 ++--
 drivers/vhost/scsi.c                     |  6 ++---
 drivers/xen/xen-scsiback.c               |  5 ++--
 include/target/iscsi/iscsi_target_core.h |  1 +
 include/target/target_core_base.h        |  7 ++---
 10 files changed, 59 insertions(+), 24 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index 05290966e630..a1725a054749 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -4277,9 +4277,9 @@ static struct qla_tgt_cmd *qlt_get_tag(scsi_qla_host_t *vha,
 {
 	struct se_session *se_sess = sess->se_sess;
 	struct qla_tgt_cmd *cmd;
-	int tag;
+	int tag, cpu;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 	if (tag < 0)
 		return NULL;
 
@@ -4292,6 +4292,7 @@ static struct qla_tgt_cmd *qlt_get_tag(scsi_qla_host_t *vha,
 	qlt_incr_num_pend_cmds(vha);
 	cmd->vha = vha;
 	cmd->se_cmd.map_tag = tag;
+	cmd->se_cmd.map_cpu = cpu;
 	cmd->sess = sess;
 	cmd->loop_id = sess->loop_id;
 	cmd->conf_compl_supported = sess->conf_compl_supported;
@@ -5294,7 +5295,7 @@ qlt_alloc_qfull_cmd(struct scsi_qla_host *vha,
 	struct fc_port *sess;
 	struct se_session *se_sess;
 	struct qla_tgt_cmd *cmd;
-	int tag;
+	int tag, cpu;
 	unsigned long flags;
 
 	if (unlikely(tgt->tgt_stop)) {
@@ -5326,7 +5327,7 @@ qlt_alloc_qfull_cmd(struct scsi_qla_host *vha,
 
 	se_sess = sess->se_sess;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 	if (tag < 0)
 		return;
 
@@ -5357,6 +5358,7 @@ qlt_alloc_qfull_cmd(struct scsi_qla_host *vha,
 	cmd->reset_count = ha->base_qpair->chip_reset;
 	cmd->q_full = 1;
 	cmd->qpair = ha->base_qpair;
+	cmd->se_cmd.map_cpu = cpu;
 
 	if (qfull) {
 		cmd->q_full = 1;
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 7e98697cfb8e..8cfcf9033507 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -17,7 +17,7 @@
  ******************************************************************************/
 
 #include <linux/list.h>
-#include <linux/percpu_ida.h>
+#include <linux/sched/signal.h>
 #include <net/ipv6.h>         /* ipv6_addr_equal() */
 #include <scsi/scsi_tcq.h>
 #include <scsi/iscsi_proto.h>
@@ -147,6 +147,30 @@ void iscsit_free_r2ts_from_list(struct iscsi_cmd *cmd)
 	spin_unlock_bh(&cmd->r2t_lock);
 }
 
+static int iscsit_wait_for_tag(struct se_session *se_sess, int state, int *cpup)
+{
+	int tag = -1;
+	DEFINE_WAIT(wait);
+	struct sbq_wait_state *ws;
+
+	if (state == TASK_RUNNING)
+		return tag;
+
+	ws = &se_sess->sess_tag_pool.ws[0];
+	for (;;) {
+		prepare_to_wait_exclusive(&ws->wait, &wait, state);
+		if (signal_pending_state(state, current))
+			break;
+		tag = sbitmap_queue_get(&se_sess->sess_tag_pool, cpup);
+		if (tag >= 0)
+			break;
+		schedule();
+	}
+
+	finish_wait(&ws->wait, &wait);
+	return tag;
+}
+
 /*
  * May be called from software interrupt (timer) context for allocating
  * iSCSI NopINs.
@@ -155,9 +179,11 @@ struct iscsi_cmd *iscsit_allocate_cmd(struct iscsi_conn *conn, int state)
 {
 	struct iscsi_cmd *cmd;
 	struct se_session *se_sess = conn->sess->se_sess;
-	int size, tag;
+	int size, tag, cpu;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, state);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
+	if (tag < 0)
+		tag = iscsit_wait_for_tag(se_sess, state, &cpu);
 	if (tag < 0)
 		return NULL;
 
@@ -166,6 +192,7 @@ struct iscsi_cmd *iscsit_allocate_cmd(struct iscsi_conn *conn, int state)
 	memset(cmd, 0, size);
 
 	cmd->se_cmd.map_tag = tag;
+	cmd->se_cmd.map_cpu = cpu;
 	cmd->conn = conn;
 	cmd->data_direction = DMA_NONE;
 	INIT_LIST_HEAD(&cmd->i_conn_node);
diff --git a/drivers/target/sbp/sbp_target.c b/drivers/target/sbp/sbp_target.c
index 679ae29d25ab..42b21f2ac8b0 100644
--- a/drivers/target/sbp/sbp_target.c
+++ b/drivers/target/sbp/sbp_target.c
@@ -926,15 +926,16 @@ static struct sbp_target_request *sbp_mgt_get_req(struct sbp_session *sess,
 {
 	struct se_session *se_sess = sess->se_sess;
 	struct sbp_target_request *req;
-	int tag;
+	int tag, cpu;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 	if (tag < 0)
 		return ERR_PTR(-ENOMEM);
 
 	req = &((struct sbp_target_request *)se_sess->sess_cmd_map)[tag];
 	memset(req, 0, sizeof(*req));
 	req->se_cmd.map_tag = tag;
+	req->se_cmd.map_cpu = cpu;
 	req->se_cmd.tag = next_orb;
 
 	return req;
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index f0e8f0f4ccb4..18c53c5cdd3d 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -260,7 +260,8 @@ int transport_alloc_session_tags(struct se_session *se_sess,
 		}
 	}
 
-	rc = percpu_ida_init(&se_sess->sess_tag_pool, tag_num);
+	rc = sbitmap_queue_init_node(&se_sess->sess_tag_pool, tag_num, -1,
+			false, GFP_KERNEL, NUMA_NO_NODE);
 	if (rc < 0) {
 		pr_err("Unable to init se_sess->sess_tag_pool,"
 			" tag_num: %u\n", tag_num);
@@ -547,7 +548,7 @@ void transport_free_session(struct se_session *se_sess)
 		target_put_nacl(se_nacl);
 	}
 	if (se_sess->sess_cmd_map) {
-		percpu_ida_destroy(&se_sess->sess_tag_pool);
+		sbitmap_queue_free(&se_sess->sess_tag_pool);
 		kvfree(se_sess->sess_cmd_map);
 	}
 	kmem_cache_free(se_sess_cache, se_sess);
diff --git a/drivers/target/tcm_fc/tfc_cmd.c b/drivers/target/tcm_fc/tfc_cmd.c
index 13e4efbe1ce7..a183d4da7db2 100644
--- a/drivers/target/tcm_fc/tfc_cmd.c
+++ b/drivers/target/tcm_fc/tfc_cmd.c
@@ -28,7 +28,6 @@
 #include <linux/configfs.h>
 #include <linux/ctype.h>
 #include <linux/hash.h>
-#include <linux/percpu_ida.h>
 #include <asm/unaligned.h>
 #include <scsi/scsi_tcq.h>
 #include <scsi/libfc.h>
@@ -448,9 +447,9 @@ static void ft_recv_cmd(struct ft_sess *sess, struct fc_frame *fp)
 	struct ft_cmd *cmd;
 	struct fc_lport *lport = sess->tport->lport;
 	struct se_session *se_sess = sess->se_sess;
-	int tag;
+	int tag, cpu;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 	if (tag < 0)
 		goto busy;
 
@@ -458,6 +457,7 @@ static void ft_recv_cmd(struct ft_sess *sess, struct fc_frame *fp)
 	memset(cmd, 0, sizeof(struct ft_cmd));
 
 	cmd->se_cmd.map_tag = tag;
+	cmd->se_cmd.map_cpu = cpu;
 	cmd->sess = sess;
 	cmd->seq = fc_seq_assign(lport, fp);
 	if (!cmd->seq) {
diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 9f670d9224b9..5003e857dce7 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -1071,15 +1071,16 @@ static struct usbg_cmd *usbg_get_cmd(struct f_uas *fu,
 {
 	struct se_session *se_sess = tv_nexus->tvn_se_sess;
 	struct usbg_cmd *cmd;
-	int tag;
+	int tag, cpu;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 	if (tag < 0)
 		return ERR_PTR(-ENOMEM);
 
 	cmd = &((struct usbg_cmd *)se_sess->sess_cmd_map)[tag];
 	memset(cmd, 0, sizeof(*cmd));
 	cmd->se_cmd.map_tag = tag;
+	cmd->se_cmd.map_cpu = cpu;
 	cmd->se_cmd.tag = cmd->tag = scsi_tag;
 	cmd->fu = fu;
 
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 70d35e696533..c9c5d6b291cc 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -46,7 +46,6 @@
 #include <linux/virtio_scsi.h>
 #include <linux/llist.h>
 #include <linux/bitmap.h>
-#include <linux/percpu_ida.h>
 
 #include "vhost.h"
 
@@ -567,7 +566,7 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
 	struct se_session *se_sess;
 	struct scatterlist *sg, *prot_sg;
 	struct page **pages;
-	int tag;
+	int tag, cpu;
 
 	tv_nexus = tpg->tpg_nexus;
 	if (!tv_nexus) {
@@ -576,7 +575,7 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
 	}
 	se_sess = tv_nexus->tvn_se_sess;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 	if (tag < 0) {
 		pr_err("Unable to obtain tag for vhost_scsi_cmd\n");
 		return ERR_PTR(-ENOMEM);
@@ -591,6 +590,7 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
 	cmd->tvc_prot_sgl = prot_sg;
 	cmd->tvc_upages = pages;
 	cmd->tvc_se_cmd.map_tag = tag;
+	cmd->tvc_se_cmd.map_cpu = cpu;
 	cmd->tvc_tag = scsi_tag;
 	cmd->tvc_lun = lun;
 	cmd->tvc_task_attr = task_attr;
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index ec6635258ed8..764dd9aa0131 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -654,9 +654,9 @@ static struct vscsibk_pend *scsiback_get_pend_req(struct vscsiif_back_ring *ring
 	struct scsiback_nexus *nexus = tpg->tpg_nexus;
 	struct se_session *se_sess = nexus->tvn_se_sess;
 	struct vscsibk_pend *req;
-	int tag, i;
+	int tag, cpu, i;
 
-	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
+	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 	if (tag < 0) {
 		pr_err("Unable to obtain tag for vscsiif_request\n");
 		return ERR_PTR(-ENOMEM);
@@ -665,6 +665,7 @@ static struct vscsibk_pend *scsiback_get_pend_req(struct vscsiif_back_ring *ring
 	req = &((struct vscsibk_pend *)se_sess->sess_cmd_map)[tag];
 	memset(req, 0, sizeof(*req));
 	req->se_cmd.map_tag = tag;
+	req->se_cmd.map_cpu = cpu;
 
 	for (i = 0; i < VSCSI_MAX_GRANTS; i++)
 		req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
diff --git a/include/target/iscsi/iscsi_target_core.h b/include/target/iscsi/iscsi_target_core.h
index cf5f3fff1f1a..f2e6abea8490 100644
--- a/include/target/iscsi/iscsi_target_core.h
+++ b/include/target/iscsi/iscsi_target_core.h
@@ -4,6 +4,7 @@
 
 #include <linux/dma-direction.h>     /* enum dma_data_direction */
 #include <linux/list.h>              /* struct list_head */
+#include <linux/sched.h>
 #include <linux/socket.h>            /* struct sockaddr_storage */
 #include <linux/types.h>             /* u8 */
 #include <scsi/iscsi_proto.h>        /* itt_t */
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 260c2f3e9460..448f291125c2 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -4,7 +4,7 @@
 
 #include <linux/configfs.h>      /* struct config_group */
 #include <linux/dma-direction.h> /* enum dma_data_direction */
-#include <linux/percpu_ida.h>    /* struct percpu_ida */
+#include <linux/sbitmap.h>
 #include <linux/percpu-refcount.h>
 #include <linux/semaphore.h>     /* struct semaphore */
 #include <linux/completion.h>
@@ -455,6 +455,7 @@ struct se_cmd {
 	int			sam_task_attr;
 	/* Used for se_sess->sess_tag_pool */
 	unsigned int		map_tag;
+	int			map_cpu;
 	/* Transport protocol dependent state, see transport_state_table */
 	enum transport_state_table t_state;
 	/* See se_cmd_flags_table */
@@ -608,7 +609,7 @@ struct se_session {
 	struct list_head	sess_wait_list;
 	spinlock_t		sess_cmd_lock;
 	void			*sess_cmd_map;
-	struct percpu_ida	sess_tag_pool;
+	struct sbitmap_queue	sess_tag_pool;
 };
 
 struct se_device;
@@ -936,7 +937,7 @@ static inline void atomic_dec_mb(atomic_t *v)
 
 static inline void target_free_tag(struct se_session *sess, struct se_cmd *cmd)
 {
-	percpu_ida_free(&sess->sess_tag_pool, cmd->map_tag);
+	sbitmap_queue_clear(&sess->sess_tag_pool, cmd->map_tag, cmd->map_cpu);
 }
 
 #endif /* TARGET_CORE_BASE_H */
-- 
2.17.1


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[PATCH 3/3] Remove percpu_ida

[Matthew Wilcox]

With its one user gone, remove the library code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/percpu_ida.h |  83 ---------
 lib/Makefile               |   2 +-
 lib/percpu_ida.c           | 370 -------------------------------------
 3 files changed, 1 insertion(+), 454 deletions(-)
 delete mode 100644 include/linux/percpu_ida.h
 delete mode 100644 lib/percpu_ida.c

diff --git a/include/linux/percpu_ida.h b/include/linux/percpu_ida.h
deleted file mode 100644
index 07d78e4653bc..000000000000
--- a/include/linux/percpu_ida.h
+++ /dev/null
@@ -1,83 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __PERCPU_IDA_H__
-#define __PERCPU_IDA_H__
-
-#include <linux/types.h>
-#include <linux/bitops.h>
-#include <linux/init.h>
-#include <linux/sched.h>
-#include <linux/spinlock_types.h>
-#include <linux/wait.h>
-#include <linux/cpumask.h>
-
-struct percpu_ida_cpu;
-
-struct percpu_ida {
-	/*
-	 * number of tags available to be allocated, as passed to
-	 * percpu_ida_init()
-	 */
-	unsigned			nr_tags;
-	unsigned			percpu_max_size;
-	unsigned			percpu_batch_size;
-
-	struct percpu_ida_cpu __percpu	*tag_cpu;
-
-	/*
-	 * Bitmap of cpus that (may) have tags on their percpu freelists:
-	 * steal_tags() uses this to decide when to steal tags, and which cpus
-	 * to try stealing from.
-	 *
-	 * It's ok for a freelist to be empty when its bit is set - steal_tags()
-	 * will just keep looking - but the bitmap _must_ be set whenever a
-	 * percpu freelist does have tags.
-	 */
-	cpumask_t			cpus_have_tags;
-
-	struct {
-		spinlock_t		lock;
-		/*
-		 * When we go to steal tags from another cpu (see steal_tags()),
-		 * we want to pick a cpu at random. Cycling through them every
-		 * time we steal is a bit easier and more or less equivalent:
-		 */
-		unsigned		cpu_last_stolen;
-
-		/* For sleeping on allocation failure */
-		wait_queue_head_t	wait;
-
-		/*
-		 * Global freelist - it's a stack where nr_free points to the
-		 * top
-		 */
-		unsigned		nr_free;
-		unsigned		*freelist;
-	} ____cacheline_aligned_in_smp;
-};
-
-/*
- * Number of tags we move between the percpu freelist and the global freelist at
- * a time
- */
-#define IDA_DEFAULT_PCPU_BATCH_MOVE	32U
-/* Max size of percpu freelist, */
-#define IDA_DEFAULT_PCPU_SIZE	((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
-
-int percpu_ida_alloc(struct percpu_ida *pool, int state);
-void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
-
-void percpu_ida_destroy(struct percpu_ida *pool);
-int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
-	unsigned long max_size, unsigned long batch_size);
-static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
-{
-	return __percpu_ida_init(pool, nr_tags, IDA_DEFAULT_PCPU_SIZE,
-		IDA_DEFAULT_PCPU_BATCH_MOVE);
-}
-
-typedef int (*percpu_ida_cb)(unsigned, void *);
-int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
-	void *data);
-
-unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu);
-#endif /* __PERCPU_IDA_H__ */
diff --git a/lib/Makefile b/lib/Makefile
index 84c6dcb31fbb..f4722a7fa62c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -40,7 +40,7 @@ obj-y += bcd.o div64.o sort.o parser.o debug_locks.o random32.o \
 	 bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
 	 gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \
 	 bsearch.o find_bit.o llist.o memweight.o kfifo.o \
-	 percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o \
+	 percpu-refcount.o rhashtable.o reciprocal_div.o \
 	 once.o refcount.o usercopy.o errseq.o bucket_locks.o
 obj-$(CONFIG_STRING_SELFTEST) += test_string.o
 obj-y += string_helpers.o
diff --git a/lib/percpu_ida.c b/lib/percpu_ida.c
deleted file mode 100644
index 9bbd9c5d375a..000000000000
--- a/lib/percpu_ida.c
+++ /dev/null
@@ -1,370 +0,0 @@
-/*
- * Percpu IDA library
- *
- * Copyright (C) 2013 Datera, Inc. Kent Overstreet
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2, or (at
- * your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- */
-
-#include <linux/mm.h>
-#include <linux/bitmap.h>
-#include <linux/bitops.h>
-#include <linux/bug.h>
-#include <linux/err.h>
-#include <linux/export.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/percpu.h>
-#include <linux/sched/signal.h>
-#include <linux/string.h>
-#include <linux/spinlock.h>
-#include <linux/percpu_ida.h>
-
-struct percpu_ida_cpu {
-	/*
-	 * Even though this is percpu, we need a lock for tag stealing by remote
-	 * CPUs:
-	 */
-	spinlock_t			lock;
-
-	/* nr_free/freelist form a stack of free IDs */
-	unsigned			nr_free;
-	unsigned			freelist[];
-};
-
-static inline void move_tags(unsigned *dst, unsigned *dst_nr,
-			     unsigned *src, unsigned *src_nr,
-			     unsigned nr)
-{
-	*src_nr -= nr;
-	memcpy(dst + *dst_nr, src + *src_nr, sizeof(unsigned) * nr);
-	*dst_nr += nr;
-}
-
-/*
- * Try to steal tags from a remote cpu's percpu freelist.
- *
- * We first check how many percpu freelists have tags
- *
- * Then we iterate through the cpus until we find some tags - we don't attempt
- * to find the "best" cpu to steal from, to keep cacheline bouncing to a
- * minimum.
- */
-static inline void steal_tags(struct percpu_ida *pool,
-			      struct percpu_ida_cpu *tags)
-{
-	unsigned cpus_have_tags, cpu = pool->cpu_last_stolen;
-	struct percpu_ida_cpu *remote;
-
-	for (cpus_have_tags = cpumask_weight(&pool->cpus_have_tags);
-	     cpus_have_tags; cpus_have_tags--) {
-		cpu = cpumask_next(cpu, &pool->cpus_have_tags);
-
-		if (cpu >= nr_cpu_ids) {
-			cpu = cpumask_first(&pool->cpus_have_tags);
-			if (cpu >= nr_cpu_ids)
-				BUG();
-		}
-
-		pool->cpu_last_stolen = cpu;
-		remote = per_cpu_ptr(pool->tag_cpu, cpu);
-
-		cpumask_clear_cpu(cpu, &pool->cpus_have_tags);
-
-		if (remote == tags)
-			continue;
-
-		spin_lock(&remote->lock);
-
-		if (remote->nr_free) {
-			memcpy(tags->freelist,
-			       remote->freelist,
-			       sizeof(unsigned) * remote->nr_free);
-
-			tags->nr_free = remote->nr_free;
-			remote->nr_free = 0;
-		}
-
-		spin_unlock(&remote->lock);
-
-		if (tags->nr_free)
-			break;
-	}
-}
-
-/*
- * Pop up to IDA_PCPU_BATCH_MOVE IDs off the global freelist, and push them onto
- * our percpu freelist:
- */
-static inline void alloc_global_tags(struct percpu_ida *pool,
-				     struct percpu_ida_cpu *tags)
-{
-	move_tags(tags->freelist, &tags->nr_free,
-		  pool->freelist, &pool->nr_free,
-		  min(pool->nr_free, pool->percpu_batch_size));
-}
-
-/**
- * percpu_ida_alloc - allocate a tag
- * @pool: pool to allocate from
- * @state: task state for prepare_to_wait
- *
- * Returns a tag - an integer in the range [0..nr_tags) (passed to
- * tag_pool_init()), or otherwise -ENOSPC on allocation failure.
- *
- * Safe to be called from interrupt context (assuming it isn't passed
- * TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, of course).
- *
- * @gfp indicates whether or not to wait until a free id is available (it's not
- * used for internal memory allocations); thus if passed __GFP_RECLAIM we may sleep
- * however long it takes until another thread frees an id (same semantics as a
- * mempool).
- *
- * Will not fail if passed TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE.
- */
-int percpu_ida_alloc(struct percpu_ida *pool, int state)
-{
-	DEFINE_WAIT(wait);
-	struct percpu_ida_cpu *tags;
-	unsigned long flags;
-	int tag = -ENOSPC;
-
-	tags = raw_cpu_ptr(pool->tag_cpu);
-	spin_lock_irqsave(&tags->lock, flags);
-
-	/* Fastpath */
-	if (likely(tags->nr_free >= 0)) {
-		tag = tags->freelist[--tags->nr_free];
-		spin_unlock_irqrestore(&tags->lock, flags);
-		return tag;
-	}
-	spin_unlock_irqrestore(&tags->lock, flags);
-
-	while (1) {
-		spin_lock_irqsave(&pool->lock, flags);
-		tags = this_cpu_ptr(pool->tag_cpu);
-
-		/*
-		 * prepare_to_wait() must come before steal_tags(), in case
-		 * percpu_ida_free() on another cpu flips a bit in
-		 * cpus_have_tags
-		 *
-		 * global lock held and irqs disabled, don't need percpu lock
-		 */
-		if (state != TASK_RUNNING)
-			prepare_to_wait(&pool->wait, &wait, state);
-
-		if (!tags->nr_free)
-			alloc_global_tags(pool, tags);
-		if (!tags->nr_free)
-			steal_tags(pool, tags);
-
-		if (tags->nr_free) {
-			tag = tags->freelist[--tags->nr_free];
-			if (tags->nr_free)
-				cpumask_set_cpu(smp_processor_id(),
-						&pool->cpus_have_tags);
-		}
-
-		spin_unlock_irqrestore(&pool->lock, flags);
-
-		if (tag >= 0 || state == TASK_RUNNING)
-			break;
-
-		if (signal_pending_state(state, current)) {
-			tag = -ERESTARTSYS;
-			break;
-		}
-
-		schedule();
-	}
-	if (state != TASK_RUNNING)
-		finish_wait(&pool->wait, &wait);
-
-	return tag;
-}
-EXPORT_SYMBOL_GPL(percpu_ida_alloc);
-
-/**
- * percpu_ida_free - free a tag
- * @pool: pool @tag was allocated from
- * @tag: a tag previously allocated with percpu_ida_alloc()
- *
- * Safe to be called from interrupt context.
- */
-void percpu_ida_free(struct percpu_ida *pool, unsigned tag)
-{
-	struct percpu_ida_cpu *tags;
-	unsigned long flags;
-	unsigned nr_free;
-
-	BUG_ON(tag >= pool->nr_tags);
-
-	tags = raw_cpu_ptr(pool->tag_cpu);
-
-	spin_lock_irqsave(&tags->lock, flags);
-	tags->freelist[tags->nr_free++] = tag;
-
-	nr_free = tags->nr_free;
-
-	if (nr_free == 1) {
-		cpumask_set_cpu(smp_processor_id(),
-				&pool->cpus_have_tags);
-		wake_up(&pool->wait);
-	}
-	spin_unlock_irqrestore(&tags->lock, flags);
-
-	if (nr_free == pool->percpu_max_size) {
-		spin_lock_irqsave(&pool->lock, flags);
-		spin_lock(&tags->lock);
-
-		if (tags->nr_free == pool->percpu_max_size) {
-			move_tags(pool->freelist, &pool->nr_free,
-				  tags->freelist, &tags->nr_free,
-				  pool->percpu_batch_size);
-
-			wake_up(&pool->wait);
-		}
-		spin_unlock(&tags->lock);
-		spin_unlock_irqrestore(&pool->lock, flags);
-	}
-}
-EXPORT_SYMBOL_GPL(percpu_ida_free);
-
-/**
- * percpu_ida_destroy - release a tag pool's resources
- * @pool: pool to free
- *
- * Frees the resources allocated by percpu_ida_init().
- */
-void percpu_ida_destroy(struct percpu_ida *pool)
-{
-	free_percpu(pool->tag_cpu);
-	free_pages((unsigned long) pool->freelist,
-		   get_order(pool->nr_tags * sizeof(unsigned)));
-}
-EXPORT_SYMBOL_GPL(percpu_ida_destroy);
-
-/**
- * percpu_ida_init - initialize a percpu tag pool
- * @pool: pool to initialize
- * @nr_tags: number of tags that will be available for allocation
- *
- * Initializes @pool so that it can be used to allocate tags - integers in the
- * range [0, nr_tags). Typically, they'll be used by driver code to refer to a
- * preallocated array of tag structures.
- *
- * Allocation is percpu, but sharding is limited by nr_tags - for best
- * performance, the workload should not span more cpus than nr_tags / 128.
- */
-int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
-	unsigned long max_size, unsigned long batch_size)
-{
-	unsigned i, cpu, order;
-
-	memset(pool, 0, sizeof(*pool));
-
-	init_waitqueue_head(&pool->wait);
-	spin_lock_init(&pool->lock);
-	pool->nr_tags = nr_tags;
-	pool->percpu_max_size = max_size;
-	pool->percpu_batch_size = batch_size;
-
-	/* Guard against overflow */
-	if (nr_tags > (unsigned) INT_MAX + 1) {
-		pr_err("percpu_ida_init(): nr_tags too large\n");
-		return -EINVAL;
-	}
-
-	order = get_order(nr_tags * sizeof(unsigned));
-	pool->freelist = (void *) __get_free_pages(GFP_KERNEL, order);
-	if (!pool->freelist)
-		return -ENOMEM;
-
-	for (i = 0; i < nr_tags; i++)
-		pool->freelist[i] = i;
-
-	pool->nr_free = nr_tags;
-
-	pool->tag_cpu = __alloc_percpu(sizeof(struct percpu_ida_cpu) +
-				       pool->percpu_max_size * sizeof(unsigned),
-				       sizeof(unsigned));
-	if (!pool->tag_cpu)
-		goto err;
-
-	for_each_possible_cpu(cpu)
-		spin_lock_init(&per_cpu_ptr(pool->tag_cpu, cpu)->lock);
-
-	return 0;
-err:
-	percpu_ida_destroy(pool);
-	return -ENOMEM;
-}
-EXPORT_SYMBOL_GPL(__percpu_ida_init);
-
-/**
- * percpu_ida_for_each_free - iterate free ids of a pool
- * @pool: pool to iterate
- * @fn: interate callback function
- * @data: parameter for @fn
- *
- * Note, this doesn't guarantee to iterate all free ids restrictly. Some free
- * ids might be missed, some might be iterated duplicated, and some might
- * be iterated and not free soon.
- */
-int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
-	void *data)
-{
-	unsigned long flags;
-	struct percpu_ida_cpu *remote;
-	unsigned cpu, i, err = 0;
-
-	for_each_possible_cpu(cpu) {
-		remote = per_cpu_ptr(pool->tag_cpu, cpu);
-		spin_lock_irqsave(&remote->lock, flags);
-		for (i = 0; i < remote->nr_free; i++) {
-			err = fn(remote->freelist[i], data);
-			if (err)
-				break;
-		}
-		spin_unlock_irqrestore(&remote->lock, flags);
-		if (err)
-			goto out;
-	}
-
-	spin_lock_irqsave(&pool->lock, flags);
-	for (i = 0; i < pool->nr_free; i++) {
-		err = fn(pool->freelist[i], data);
-		if (err)
-			break;
-	}
-	spin_unlock_irqrestore(&pool->lock, flags);
-out:
-	return err;
-}
-EXPORT_SYMBOL_GPL(percpu_ida_for_each_free);
-
-/**
- * percpu_ida_free_tags - return free tags number of a specific cpu or global pool
- * @pool: pool related
- * @cpu: specific cpu or global pool if @cpu == nr_cpu_ids
- *
- * Note: this just returns a snapshot of free tags number.
- */
-unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu)
-{
-	struct percpu_ida_cpu *remote;
-	if (cpu == nr_cpu_ids)
-		return pool->nr_free;
-	remote = per_cpu_ptr(pool->tag_cpu, cpu);
-	return remote->nr_free;
-}
-EXPORT_SYMBOL_GPL(percpu_ida_free_tags);
-- 
2.17.1


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Re: [PATCH 0/3] Use sbitmap instead of percpu_ida

[Bart Van Assche]

On Tue, 2018-06-12 at 12:05 -0700, Matthew Wilcox wrote:
> Removing the percpu_ida code nets over 400 lines of removal.  It's not
> as spectacular as deleting an entire architecture, but it's still a
> worthy reduction in lines of code.
> 
> Untested due to lack of hardware and not understanding how to set up a
> target platform.
> 
> Changes from v1:
>  - Fixed bugs pointed out by Jens in iscsit_wait_for_tag()
>  - Abstracted out tag freeing as requested by Bart
>  - Made iscsit_wait_for_tag static as pointed out by 0day

For the whole series:

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>

Thanks,

Bart.

Re: [PATCH 0/3] Use sbitmap instead of percpu_ida

[Jens Axboe]

On 6/12/18 1:05 PM, Matthew Wilcox wrote:
> Removing the percpu_ida code nets over 400 lines of removal.  It's not
> as spectacular as deleting an entire architecture, but it's still a
> worthy reduction in lines of code.
> 
> Untested due to lack of hardware and not understanding how to set up a
> target platform.
> 
> Changes from v1:
>  - Fixed bugs pointed out by Jens in iscsit_wait_for_tag()
>  - Abstracted out tag freeing as requested by Bart
>  - Made iscsit_wait_for_tag static as pointed out by 0day

Reviewed-by: Jens Axboe <axboe@kernel.dk>

-- 
Jens Axboe

Re: [PATCH 0/3] Use sbitmap instead of percpu_ida

[Martin K. Petersen]

Matthew,

> Removing the percpu_ida code nets over 400 lines of removal.  It's not
> as spectacular as deleting an entire architecture, but it's still a
> worthy reduction in lines of code.

Since most of the changes are in scsi or target, should I take this
series through my tree?

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH 0/3] Use sbitmap instead of percpu_ida

[Matthew Wilcox]

On Thu, Jun 14, 2018 at 10:06:58PM -0400, Martin K. Petersen wrote:
> 
> Matthew,
> 
> > Removing the percpu_ida code nets over 400 lines of removal.  It's not
> > as spectacular as deleting an entire architecture, but it's still a
> > worthy reduction in lines of code.
> 
> Since most of the changes are in scsi or target, should I take this
> series through my tree?

I'd welcome that.  Nick seems to be inactive as target maintainer;
his tree on kernel.org hasn't seen any updates in five months.

Thanks!

Re: [PATCH 0/3] Use sbitmap instead of percpu_ida

[Martin K. Petersen]

Matthew,

>> Since most of the changes are in scsi or target, should I take this
>> series through my tree?
>
> I'd welcome that.  Nick seems to be inactive as target maintainer;
> his tree on kernel.org hasn't seen any updates in five months.

Applied to 4.19/scsi-queue, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH 0/3] Use sbitmap instead of percpu_ida

[Christoph Hellwig]

Btw, if you are on a spree to remove almost unused data structures
from target code, the lib/btree.c code is only used by the qla2xxx
target code, and doesn't really look like the best fit for it either.