[PATCH 0/9] iscsi features for 5.20

[PATCH 0/9] iscsi features for 5.20

[Mike Christie]

The following patches are for 5.20. They were built against Linus's tree
but they have no conflicts with the existing patches on the list and
can be applied before or after those patches. The patches also apply over
Martin's staging and queueing branches.

The bulk of the patches allow us to run from a workqueue instead of always
running from the net softirq. When using lots of sessions we see a nice
perf bump when doing throughput and IOPs tests. There's then some cleanups
and locking improvements.

[PATCH 1/9] scsi: iscsi: Rename iscsi_conn_queue_work()

[Mike Christie]

Rename iscsi_conn_queue_work() to iscsi_conn_queue_xmit() to reflect that
it handles queueing of xmits only.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Wu Bo <wubo40@huawei.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/cxgbi/libcxgbi.c |  2 +-
 drivers/scsi/iscsi_tcp.c      |  2 +-
 drivers/scsi/libiscsi.c       | 12 ++++++------
 include/scsi/libiscsi.h       |  2 +-
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/cxgbi/libcxgbi.c b/drivers/scsi/cxgbi/libcxgbi.c
index 4365d52c6430..411b0d386fad 100644
--- a/drivers/scsi/cxgbi/libcxgbi.c
+++ b/drivers/scsi/cxgbi/libcxgbi.c
@@ -1455,7 +1455,7 @@ void cxgbi_conn_tx_open(struct cxgbi_sock *csk)
 	if (conn) {
 		log_debug(1 << CXGBI_DBG_SOCK,
 			"csk 0x%p, cid %d.\n", csk, conn->id);
-		iscsi_conn_queue_work(conn);
+		iscsi_conn_queue_xmit(conn);
 	}
 }
 EXPORT_SYMBOL_GPL(cxgbi_conn_tx_open);
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 9fee70d6434a..c775acc5208d 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -205,7 +205,7 @@ static void iscsi_sw_tcp_write_space(struct sock *sk)
 	old_write_space(sk);
 
 	ISCSI_SW_TCP_DBG(conn, "iscsi_write_space\n");
-	iscsi_conn_queue_work(conn);
+	iscsi_conn_queue_xmit(conn);
 }
 
 static void iscsi_sw_tcp_conn_set_callbacks(struct iscsi_conn *conn)
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 8d78559ae94a..3a73aadc96a4 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -83,7 +83,7 @@ MODULE_PARM_DESC(debug_libiscsi_eh,
 				"%s " dbg_fmt, __func__, ##arg);	\
 	} while (0);
 
-inline void iscsi_conn_queue_work(struct iscsi_conn *conn)
+inline void iscsi_conn_queue_xmit(struct iscsi_conn *conn)
 {
 	struct Scsi_Host *shost = conn->session->host;
 	struct iscsi_host *ihost = shost_priv(shost);
@@ -91,7 +91,7 @@ inline void iscsi_conn_queue_work(struct iscsi_conn *conn)
 	if (ihost->workq)
 		queue_work(ihost->workq, &conn->xmitwork);
 }
-EXPORT_SYMBOL_GPL(iscsi_conn_queue_work);
+EXPORT_SYMBOL_GPL(iscsi_conn_queue_xmit);
 
 static void __iscsi_update_cmdsn(struct iscsi_session *session,
 				 uint32_t exp_cmdsn, uint32_t max_cmdsn)
@@ -765,7 +765,7 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 			goto free_task;
 	} else {
 		list_add_tail(&task->running, &conn->mgmtqueue);
-		iscsi_conn_queue_work(conn);
+		iscsi_conn_queue_xmit(conn);
 	}
 
 	return task;
@@ -1513,7 +1513,7 @@ void iscsi_requeue_task(struct iscsi_task *task)
 		 */
 		iscsi_put_task(task);
 	}
-	iscsi_conn_queue_work(conn);
+	iscsi_conn_queue_xmit(conn);
 	spin_unlock_bh(&conn->session->frwd_lock);
 }
 EXPORT_SYMBOL_GPL(iscsi_requeue_task);
@@ -1786,7 +1786,7 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
 		}
 	} else {
 		list_add_tail(&task->running, &conn->cmdqueue);
-		iscsi_conn_queue_work(conn);
+		iscsi_conn_queue_xmit(conn);
 	}
 
 	session->queued_cmdsn++;
@@ -1967,7 +1967,7 @@ EXPORT_SYMBOL_GPL(iscsi_suspend_tx);
 static void iscsi_start_tx(struct iscsi_conn *conn)
 {
 	clear_bit(ISCSI_CONN_FLAG_SUSPEND_TX, &conn->flags);
-	iscsi_conn_queue_work(conn);
+	iscsi_conn_queue_xmit(conn);
 }
 
 /*
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index c0703cd20a99..4f4be93aa0d9 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -453,7 +453,7 @@ extern int iscsi_conn_get_addr_param(struct sockaddr_storage *addr,
 				     enum iscsi_param param, char *buf);
 extern void iscsi_suspend_tx(struct iscsi_conn *conn);
 extern void iscsi_suspend_queue(struct iscsi_conn *conn);
-extern void iscsi_conn_queue_work(struct iscsi_conn *conn);
+extern void iscsi_conn_queue_xmit(struct iscsi_conn *conn);
 
 #define iscsi_conn_printk(prefix, _c, fmt, a...) \
 	iscsi_cls_conn_printk(prefix, ((struct iscsi_conn *)_c)->cls_conn, \
-- 
2.25.1

[PATCH 2/9] scsi: iscsi: Add recv workqueue helpers

[Mike Christie]

Add helpers to allow the drivers to run their recv paths from libiscsi's
workqueue.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/libiscsi.c | 29 +++++++++++++++++++++++++++--
 include/scsi/libiscsi.h |  4 ++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 3a73aadc96a4..44283014c4eb 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -93,6 +93,16 @@ inline void iscsi_conn_queue_xmit(struct iscsi_conn *conn)
 }
 EXPORT_SYMBOL_GPL(iscsi_conn_queue_xmit);
 
+inline void iscsi_conn_queue_recv(struct iscsi_conn *conn)
+{
+	struct Scsi_Host *shost = conn->session->host;
+	struct iscsi_host *ihost = shost_priv(shost);
+
+	if (ihost->workq && !test_bit(ISCSI_CONN_FLAG_SUSPEND_RX, &conn->flags))
+		queue_work(ihost->workq, &conn->recvwork);
+}
+EXPORT_SYMBOL_GPL(iscsi_conn_queue_recv);
+
 static void __iscsi_update_cmdsn(struct iscsi_session *session,
 				 uint32_t exp_cmdsn, uint32_t max_cmdsn)
 {
@@ -1947,7 +1957,7 @@ EXPORT_SYMBOL_GPL(iscsi_suspend_queue);
 
 /**
  * iscsi_suspend_tx - suspend iscsi_data_xmit
- * @conn: iscsi conn tp stop processing IO on.
+ * @conn: iscsi conn to stop processing IO on.
  *
  * This function sets the suspend bit to prevent iscsi_data_xmit
  * from sending new IO, and if work is queued on the xmit thread
@@ -1960,7 +1970,7 @@ void iscsi_suspend_tx(struct iscsi_conn *conn)
 
 	set_bit(ISCSI_CONN_FLAG_SUSPEND_TX, &conn->flags);
 	if (ihost->workq)
-		flush_workqueue(ihost->workq);
+		flush_work(&conn->xmitwork);
 }
 EXPORT_SYMBOL_GPL(iscsi_suspend_tx);
 
@@ -1970,6 +1980,21 @@ static void iscsi_start_tx(struct iscsi_conn *conn)
 	iscsi_conn_queue_xmit(conn);
 }
 
+/**
+ * iscsi_suspend_rx - Prevent recvwork from running again.
+ * @conn: iscsi conn to stop.
+ */
+void iscsi_suspend_rx(struct iscsi_conn *conn)
+{
+	struct Scsi_Host *shost = conn->session->host;
+	struct iscsi_host *ihost = shost_priv(shost);
+
+	set_bit(ISCSI_CONN_FLAG_SUSPEND_RX, &conn->flags);
+	if (ihost->workq)
+		flush_work(&conn->recvwork);
+}
+EXPORT_SYMBOL_GPL(iscsi_suspend_rx);
+
 /*
  * We want to make sure a ping is in flight. It has timed out.
  * And we are not busy processing a pdu that is making
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 4f4be93aa0d9..b4700de3445a 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -213,6 +213,8 @@ struct iscsi_conn {
 	struct list_head	cmdqueue;	/* data-path cmd queue */
 	struct list_head	requeue;	/* tasks needing another run */
 	struct work_struct	xmitwork;	/* per-conn. xmit workqueue */
+	/* recv */
+	struct work_struct	recvwork;
 	unsigned long		flags;		/* ISCSI_CONN_FLAGs */
 
 	/* negotiated params */
@@ -452,8 +454,10 @@ extern int iscsi_conn_get_param(struct iscsi_cls_conn *cls_conn,
 extern int iscsi_conn_get_addr_param(struct sockaddr_storage *addr,
 				     enum iscsi_param param, char *buf);
 extern void iscsi_suspend_tx(struct iscsi_conn *conn);
+extern void iscsi_suspend_rx(struct iscsi_conn *conn);
 extern void iscsi_suspend_queue(struct iscsi_conn *conn);
 extern void iscsi_conn_queue_xmit(struct iscsi_conn *conn);
+extern void iscsi_conn_queue_recv(struct iscsi_conn *conn);
 
 #define iscsi_conn_printk(prefix, _c, fmt, a...) \
 	iscsi_cls_conn_printk(prefix, ((struct iscsi_conn *)_c)->cls_conn, \
-- 
2.25.1

[PATCH 3/9] scsi: iscsi: Run recv path from workqueue

[Mike Christie]

We don't always want to run the recv path from the network softirq because
when we have to have multiple sessions sharing the same CPUs, some sessions
can eat up the NAPI softirq budget and affect other sessions or users.

Allow us to queue the recv handling to the iscsi workqueue so we can have
the scheduler/wq code try to balance the work and CPU use across all
sessions' worker threads.

Note: It wasn't the original intent of the change but a nice side effect is
that for some workloads/configs we get a nice performance boost. For a
simple read heavy test:

  fio --direct=1 --filename=/dev/dm-0  --rw=randread --bs=256K
    --ioengine=libaio --iodepth=128 --numjobs=4

where the iscsi threads, fio jobs, and rps_cpus share CPUs we see a 32%
throughput boost. We also see increases for small I/O IOPs tests but it's
not as high.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/iscsi_tcp.c | 65 ++++++++++++++++++++++++++++++++--------
 drivers/scsi/iscsi_tcp.h |  2 ++
 2 files changed, 54 insertions(+), 13 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index c775acc5208d..d6d329fbbfcc 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -52,6 +52,10 @@ static struct iscsi_transport iscsi_sw_tcp_transport;
 static unsigned int iscsi_max_lun = ~0;
 module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);
 
+static bool iscsi_recv_from_iscsi_q;
+module_param_named(recv_from_iscsi_q, iscsi_recv_from_iscsi_q, bool, 0644);
+MODULE_PARM_DESC(recv_from_iscsi_q, "Set to true to read iSCSI data/headers from the iscsi_q workqueue. The default is false which will perform reads from the network softirq context.");
+
 static int iscsi_sw_tcp_dbg;
 module_param_named(debug_iscsi_tcp, iscsi_sw_tcp_dbg, int,
 		   S_IRUGO | S_IWUSR);
@@ -122,20 +126,13 @@ static inline int iscsi_sw_sk_state_check(struct sock *sk)
 	return 0;
 }
 
-static void iscsi_sw_tcp_data_ready(struct sock *sk)
+static void iscsi_sw_tcp_recv_data(struct iscsi_conn *conn)
 {
-	struct iscsi_conn *conn;
-	struct iscsi_tcp_conn *tcp_conn;
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct sock *sk = tcp_sw_conn->sock->sk;
 	read_descriptor_t rd_desc;
 
-	read_lock_bh(&sk->sk_callback_lock);
-	conn = sk->sk_user_data;
-	if (!conn) {
-		read_unlock_bh(&sk->sk_callback_lock);
-		return;
-	}
-	tcp_conn = conn->dd_data;
-
 	/*
 	 * Use rd_desc to pass 'conn' to iscsi_tcp_recv.
 	 * We set count to 1 because we want the network layer to
@@ -144,13 +141,48 @@ static void iscsi_sw_tcp_data_ready(struct sock *sk)
 	 */
 	rd_desc.arg.data = conn;
 	rd_desc.count = 1;
-	tcp_read_sock(sk, &rd_desc, iscsi_sw_tcp_recv);
 
-	iscsi_sw_sk_state_check(sk);
+	tcp_read_sock(sk, &rd_desc, iscsi_sw_tcp_recv);
 
 	/* If we had to (atomically) map a highmem page,
 	 * unmap it now. */
 	iscsi_tcp_segment_unmap(&tcp_conn->in.segment);
+
+	iscsi_sw_sk_state_check(sk);
+}
+
+static void iscsi_sw_tcp_recv_data_work(struct work_struct *work)
+{
+	struct iscsi_conn *conn = container_of(work, struct iscsi_conn,
+					       recvwork);
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct sock *sk = tcp_sw_conn->sock->sk;
+
+	lock_sock(sk);
+	iscsi_sw_tcp_recv_data(conn);
+	release_sock(sk);
+}
+
+static void iscsi_sw_tcp_data_ready(struct sock *sk)
+{
+	struct iscsi_sw_tcp_conn *tcp_sw_conn;
+	struct iscsi_tcp_conn *tcp_conn;
+	struct iscsi_conn *conn;
+
+	read_lock_bh(&sk->sk_callback_lock);
+	conn = sk->sk_user_data;
+	if (!conn) {
+		read_unlock_bh(&sk->sk_callback_lock);
+		return;
+	}
+	tcp_conn = conn->dd_data;
+	tcp_sw_conn = tcp_conn->dd_data;
+
+	if (tcp_sw_conn->queue_recv)
+		iscsi_conn_queue_recv(conn);
+	else
+		iscsi_sw_tcp_recv_data(conn);
 	read_unlock_bh(&sk->sk_callback_lock);
 }
 
@@ -276,6 +308,9 @@ static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
 		if (segment->total_copied + segment->size < segment->total_size)
 			flags |= MSG_MORE;
 
+		if (tcp_sw_conn->queue_recv)
+			flags |= MSG_DONTWAIT;
+
 		/* Use sendpage if we can; else fall back to sendmsg */
 		if (!segment->data) {
 			sg = segment->sg;
@@ -557,6 +592,8 @@ iscsi_sw_tcp_conn_create(struct iscsi_cls_session *cls_session,
 	conn = cls_conn->dd_data;
 	tcp_conn = conn->dd_data;
 	tcp_sw_conn = tcp_conn->dd_data;
+	INIT_WORK(&conn->recvwork, iscsi_sw_tcp_recv_data_work);
+	tcp_sw_conn->queue_recv = iscsi_recv_from_iscsi_q;
 
 	tfm = crypto_alloc_ahash("crc32c", 0, CRYPTO_ALG_ASYNC);
 	if (IS_ERR(tfm))
@@ -610,6 +647,8 @@ static void iscsi_sw_tcp_release_conn(struct iscsi_conn *conn)
 	iscsi_sw_tcp_conn_restore_callbacks(conn);
 	sock_put(sock->sk);
 
+	iscsi_suspend_rx(conn);
+
 	spin_lock_bh(&session->frwd_lock);
 	tcp_sw_conn->sock = NULL;
 	spin_unlock_bh(&session->frwd_lock);
diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
index 791453195099..850a018aefb9 100644
--- a/drivers/scsi/iscsi_tcp.h
+++ b/drivers/scsi/iscsi_tcp.h
@@ -28,6 +28,8 @@ struct iscsi_sw_tcp_send {
 
 struct iscsi_sw_tcp_conn {
 	struct socket		*sock;
+	struct work_struct	recvwork;
+	bool			queue_recv;
 
 	struct iscsi_sw_tcp_send out;
 	/* old values for socket callbacks */
-- 
2.25.1

[PATCH 4/9] scsi: iscsi_tcp: Tell net when there's more data

[Mike Christie]

If we have more data set the MSG_SENDPAGE_NOTLAST in case we go down the
sendpage path.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/iscsi_tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index d6d329fbbfcc..df38c6c10aa9 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -306,7 +306,7 @@ static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
 		copy = segment->size - offset;
 
 		if (segment->total_copied + segment->size < segment->total_size)
-			flags |= MSG_MORE;
+			flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
 
 		if (tcp_sw_conn->queue_recv)
 			flags |= MSG_DONTWAIT;
-- 
2.25.1

[PATCH 5/9] scsi: iscsi_tcp: Drop target_alloc use

[Mike Christie]

For software iSCSI, we do a session per host so there is no need to set the
target's can_queue since it's the same as the host one. Setting it just
results in extra atomic checks in the main I/O path.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Wu Bo <wubo40@huawei.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/iscsi_tcp.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index df38c6c10aa9..2cfd40cf2859 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -1042,7 +1042,6 @@ static struct scsi_host_template iscsi_sw_tcp_sht = {
 	.eh_target_reset_handler = iscsi_eh_recover_target,
 	.dma_boundary		= PAGE_SIZE - 1,
 	.slave_configure        = iscsi_sw_tcp_slave_configure,
-	.target_alloc		= iscsi_target_alloc,
 	.proc_name		= "iscsi_tcp",
 	.this_id		= -1,
 	.track_queue_depth	= 1,
-- 
2.25.1

[PATCH 6/9] scsi: iscsi: Remove unneeded task state check

[Mike Christie]

Commit 5923d64b7ab6 ("scsi: libiscsi: Drop taskqueuelock") added an extra
task->state because for commit 6f8830f5bbab ("scsi: libiscsi: add lock
around task lists to fix list corruption regression") we didn't know why we
ended up with cmds on the list and thought it might have been a bad target
sending a response while we were still sending the cmd. We were never able
to get a target to send us a response early, because it turns out the bug
was just a race in libiscsi/libiscsi_tcp where:

 1. iscsi_tcp_r2t_rsp() queues a r2t to tcp_task->r2tqueue.

 2. iscsi_tcp_task_xmit() runs iscsi_tcp_get_curr_r2t() and sees we have a
    r2t. It dequeues it and iscsi_tcp_task_xmit() starts to process it.

 3. iscsi_tcp_r2t_rsp() runs iscsi_requeue_task() and puts the task on the
    requeue list.

 4. iscsi_tcp_task_xmit() sends the data for r2t. This is the final chunk
    of data, so the cmd is done.

 5. target sends the response.

 6. On a different CPU from #3, iscsi_complete_task() processes the
    response.  Since there was no common lock for the list, the lists/tasks
    pointers are not fully in sync, so could end up with list corruption.

Since it was just a race on our side, remove the extra check and fix up the
comments.

Reviewed-by: Wu Bo <wubo40@huawei.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/libiscsi.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 44283014c4eb..1d646f02d516 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -567,16 +567,19 @@ static bool cleanup_queued_task(struct iscsi_task *task)
 	struct iscsi_conn *conn = task->conn;
 	bool early_complete = false;
 
-	/* Bad target might have completed task while it was still running */
+	/*
+	 * We might have raced where we handled a R2T early and got a response
+	 * but have not yet taken the task off the requeue list, then a TMF or
+	 * recovery happened and so we can still see it here.
+	 */
 	if (task->state == ISCSI_TASK_COMPLETED)
 		early_complete = true;
 
 	if (!list_empty(&task->running)) {
 		list_del_init(&task->running);
 		/*
-		 * If it's on a list but still running, this could be from
-		 * a bad target sending a rsp early, cleanup from a TMF, or
-		 * session recovery.
+		 * If it's on a list but still running this could be cleanup
+		 * from a TMF or session recovery.
 		 */
 		if (task->state == ISCSI_TASK_RUNNING ||
 		    task->state == ISCSI_TASK_COMPLETED)
@@ -1485,7 +1488,7 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 	}
 	/* regular RX path uses back_lock */
 	spin_lock(&conn->session->back_lock);
-	if (rc && task->state == ISCSI_TASK_RUNNING) {
+	if (rc) {
 		/*
 		 * get an extra ref that is released next time we access it
 		 * as conn->task above.
-- 
2.25.1

[PATCH 7/9] scsi: iscsi: Remove iscsi_get_task back_lock requirement

[Mike Christie]

We currently require that the back_lock is held when calling the functions
that manipulate the iscsi_task refcount. The only reason for this is to
handle races where we are handling SCSI-ml EH callbacks and the cmd is
completing at the same time the normal completion path is running, and we
can't return from the EH callback until the driver has stopped accessing
the cmd. Holding the back_lock while also accessing the task->state made it
simple to check that a cmd is completing and also get/put a refcount at the
same time, and at the time we were not as concerned about performance.

The problem is that we don't want to take the back_lock from the xmit path
for normal I/O since it causes contention with the completion path if the
user has chosen to try and split those paths on different CPUs (in this
case abusing the CPUs and ignoring caching improves perf for some uses).

Begins to remove the back_lock requirement for iscsi_get/put_task by
removing the requirement for the get path. Instead of always holding the
back_lock we detect if something has done the last put and is about to call
iscsi_free_task(). A subsequent commit will then allow iSCSI code to do the
last put on a task and only grab the back_lock if the refcount is now zero
and it's going to call iscsi_free_task().

Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/be2iscsi/be_main.c | 19 ++++++-
 drivers/scsi/libiscsi.c         | 95 +++++++++++++++++++++++----------
 drivers/scsi/libiscsi_tcp.c     |  6 ++-
 include/scsi/libiscsi.h         |  2 +-
 4 files changed, 89 insertions(+), 33 deletions(-)

diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
index 3bb0adefbe06..dd32a90ef9c2 100644
--- a/drivers/scsi/be2iscsi/be_main.c
+++ b/drivers/scsi/be2iscsi/be_main.c
@@ -231,6 +231,7 @@ static int beiscsi_eh_abort(struct scsi_cmnd *sc)
 	cls_session = starget_to_session(scsi_target(sc->device));
 	session = cls_session->dd_data;
 
+completion_check:
 	/* check if we raced, task just got cleaned up under us */
 	spin_lock_bh(&session->back_lock);
 	if (!abrt_task || !abrt_task->sc) {
@@ -238,7 +239,13 @@ static int beiscsi_eh_abort(struct scsi_cmnd *sc)
 		return SUCCESS;
 	}
 	/* get a task ref till FW processes the req for the ICD used */
-	__iscsi_get_task(abrt_task);
+	if (!iscsi_get_task(abrt_task)) {
+		spin_unlock(&session->back_lock);
+		/* We are just about to call iscsi_free_task so wait for it. */
+		udelay(5);
+		goto completion_check;
+	}
+
 	abrt_io_task = abrt_task->dd_data;
 	conn = abrt_task->conn;
 	beiscsi_conn = conn->dd_data;
@@ -323,7 +330,15 @@ static int beiscsi_eh_device_reset(struct scsi_cmnd *sc)
 		}
 
 		/* get a task ref till FW processes the req for the ICD used */
-		__iscsi_get_task(task);
+		if (!iscsi_get_task(task)) {
+			/*
+			 * The task has completed in the driver and is
+			 * completing in libiscsi. Just ignore it here. When we
+			 * call iscsi_eh_device_reset, it will wait for us.
+			 */
+			continue;
+		}
+
 		io_task = task->dd_data;
 		/* mark WRB invalid which have been not processed by FW yet */
 		if (is_chip_be2_be3r(phba)) {
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 1d646f02d516..07fc78aa1aa2 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -83,6 +83,8 @@ MODULE_PARM_DESC(debug_libiscsi_eh,
 				"%s " dbg_fmt, __func__, ##arg);	\
 	} while (0);
 
+#define ISCSI_CMD_COMPL_WAIT 5
+
 inline void iscsi_conn_queue_xmit(struct iscsi_conn *conn)
 {
 	struct Scsi_Host *shost = conn->session->host;
@@ -482,11 +484,11 @@ static void iscsi_free_task(struct iscsi_task *task)
 	}
 }
 
-void __iscsi_get_task(struct iscsi_task *task)
+bool iscsi_get_task(struct iscsi_task *task)
 {
-	refcount_inc(&task->refcount);
+	return refcount_inc_not_zero(&task->refcount);
 }
-EXPORT_SYMBOL_GPL(__iscsi_get_task);
+EXPORT_SYMBOL_GPL(iscsi_get_task);
 
 void __iscsi_put_task(struct iscsi_task *task)
 {
@@ -600,20 +602,17 @@ static bool cleanup_queued_task(struct iscsi_task *task)
 }
 
 /*
- * session frwd lock must be held and if not called for a task that is still
- * pending or from the xmit thread, then xmit thread must be suspended
+ * session back and frwd lock must be held and if not called for a task that
+ * is still pending or from the xmit thread, then xmit thread must be suspended
  */
-static void fail_scsi_task(struct iscsi_task *task, int err)
+static void __fail_scsi_task(struct iscsi_task *task, int err)
 {
 	struct iscsi_conn *conn = task->conn;
 	struct scsi_cmnd *sc;
 	int state;
 
-	spin_lock_bh(&conn->session->back_lock);
-	if (cleanup_queued_task(task)) {
-		spin_unlock_bh(&conn->session->back_lock);
+	if (cleanup_queued_task(task))
 		return;
-	}
 
 	if (task->state == ISCSI_TASK_PENDING) {
 		/*
@@ -632,7 +631,15 @@ static void fail_scsi_task(struct iscsi_task *task, int err)
 	sc->result = err << 16;
 	scsi_set_resid(sc, scsi_bufflen(sc));
 	iscsi_complete_task(task, state);
-	spin_unlock_bh(&conn->session->back_lock);
+}
+
+static void fail_scsi_task(struct iscsi_task *task, int err)
+{
+	struct iscsi_session *session = task->conn->session;
+
+	spin_lock_bh(&session->back_lock);
+	__fail_scsi_task(task, err);
+	spin_unlock_bh(&session->back_lock);
 }
 
 static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
@@ -1450,8 +1457,17 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 	spin_lock_bh(&conn->session->back_lock);
 
 	if (!conn->task) {
-		/* Take a ref so we can access it after xmit_task() */
-		__iscsi_get_task(task);
+		/*
+		 * Take a ref so we can access it after xmit_task().
+		 *
+		 * This should never fail because the failure paths will have
+		 * stopped the xmit thread.
+		 */
+		if (!iscsi_get_task(task)) {
+			spin_unlock_bh(&conn->session->back_lock);
+			WARN_ON_ONCE(1);
+			return 0;
+		}
 	} else {
 		/* Already have a ref from when we failed to send it last call */
 		conn->task = NULL;
@@ -1493,7 +1509,7 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 		 * get an extra ref that is released next time we access it
 		 * as conn->task above.
 		 */
-		__iscsi_get_task(task);
+		iscsi_get_task(task);
 		conn->task = task;
 	}
 
@@ -1912,6 +1928,7 @@ static void fail_scsi_tasks(struct iscsi_conn *conn, u64 lun, int error)
 	struct iscsi_task *task;
 	int i;
 
+restart_cmd_loop:
 	spin_lock_bh(&session->back_lock);
 	for (i = 0; i < session->cmds_max; i++) {
 		task = session->cmds[i];
@@ -1920,22 +1937,25 @@ static void fail_scsi_tasks(struct iscsi_conn *conn, u64 lun, int error)
 
 		if (lun != -1 && lun != task->sc->device->lun)
 			continue;
-
-		__iscsi_get_task(task);
-		spin_unlock_bh(&session->back_lock);
+		/*
+		 * The cmd is completing but if this is called from an eh
+		 * callout path then when we return scsi-ml owns the cmd. Wait
+		 * for the completion path to finish freeing the cmd.
+		 */
+		if (!iscsi_get_task(task)) {
+			spin_unlock_bh(&session->back_lock);
+			spin_unlock_bh(&session->frwd_lock);
+			udelay(ISCSI_CMD_COMPL_WAIT);
+			spin_lock_bh(&session->frwd_lock);
+			goto restart_cmd_loop;
+		}
 
 		ISCSI_DBG_SESSION(session,
 				  "failing sc %p itt 0x%x state %d\n",
 				  task->sc, task->itt, task->state);
-		fail_scsi_task(task, error);
-
-		spin_unlock_bh(&session->frwd_lock);
-		iscsi_put_task(task);
-		spin_lock_bh(&session->frwd_lock);
-
-		spin_lock_bh(&session->back_lock);
+		__fail_scsi_task(task, error);
+		__iscsi_put_task(task);
 	}
-
 	spin_unlock_bh(&session->back_lock);
 }
 
@@ -2040,7 +2060,16 @@ enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)
 		spin_unlock(&session->back_lock);
 		goto done;
 	}
-	__iscsi_get_task(task);
+	if (!iscsi_get_task(task)) {
+		/*
+		 * Racing with the completion path right now, so give it more
+		 * time so that path can complete it like normal.
+		 */
+		rc = BLK_EH_RESET_TIMER;
+		task = NULL;
+		spin_unlock(&session->back_lock);
+		goto done;
+	}
 	spin_unlock(&session->back_lock);
 
 	if (session->state != ISCSI_STATE_LOGGED_IN) {
@@ -2289,6 +2318,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 
 	ISCSI_DBG_EH(session, "aborting sc %p\n", sc);
 
+completion_check:
 	mutex_lock(&session->eh_mutex);
 	spin_lock_bh(&session->frwd_lock);
 	/*
@@ -2328,13 +2358,20 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 		return SUCCESS;
 	}
 
+	if (!iscsi_get_task(task)) {
+		spin_unlock(&session->back_lock);
+		spin_unlock_bh(&session->frwd_lock);
+		mutex_unlock(&session->eh_mutex);
+		/* We are just about to call iscsi_free_task so wait for it. */
+		udelay(ISCSI_CMD_COMPL_WAIT);
+		goto completion_check;
+	}
+
+	ISCSI_DBG_EH(session, "aborting [sc %p itt 0x%x]\n", sc, task->itt);
 	conn = session->leadconn;
 	iscsi_get_conn(conn->cls_conn);
 	conn->eh_abort_cnt++;
 	age = session->age;
-
-	ISCSI_DBG_EH(session, "aborting [sc %p itt 0x%x]\n", sc, task->itt);
-	__iscsi_get_task(task);
 	spin_unlock(&session->back_lock);
 
 	if (task->state == ISCSI_TASK_PENDING) {
diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
index 883005757ddb..c182aa83f2c9 100644
--- a/drivers/scsi/libiscsi_tcp.c
+++ b/drivers/scsi/libiscsi_tcp.c
@@ -558,7 +558,11 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 		return 0;
 	}
 	task->last_xfer = jiffies;
-	__iscsi_get_task(task);
+	if (!iscsi_get_task(task)) {
+		spin_unlock(&session->back_lock);
+		/* Let the path that got the early rsp complete it */
+		return 0;
+	}
 
 	tcp_conn = conn->dd_data;
 	rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index b4700de3445a..cf7dfd61860f 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -482,7 +482,7 @@ extern struct iscsi_task *iscsi_itt_to_task(struct iscsi_conn *, itt_t);
 extern void iscsi_requeue_task(struct iscsi_task *task);
 extern void iscsi_put_task(struct iscsi_task *task);
 extern void __iscsi_put_task(struct iscsi_task *task);
-extern void __iscsi_get_task(struct iscsi_task *task);
+extern bool iscsi_get_task(struct iscsi_task *task);
 extern void iscsi_complete_scsi_task(struct iscsi_task *task,
 				     uint32_t exp_cmdsn, uint32_t max_cmdsn);
 
-- 
2.25.1

[PATCH 8/9] scsi: iscsi: Try to avoid taking back_lock in xmit path

[Mike Christie]

We need the back lock when freeing a task, so we hold it when calling
__iscsi_put_task() from the completion path to make it easier and to avoid
having to retake it in that path. For iscsi_put_task() we just grabbed it
while also doing the decrement on the refcount but it's only really needed
if the refcount is zero and we free the task. This modifies
iscsi_put_task() to just take the lock when needed then has the xmit path
use it. Normally we will then not take the back lock from the xmit path. It
will only be rare cases where the network is so fast that we get a response
right after we send the header/data.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/libiscsi.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 07fc78aa1aa2..da292761995f 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -490,6 +490,12 @@ bool iscsi_get_task(struct iscsi_task *task)
 }
 EXPORT_SYMBOL_GPL(iscsi_get_task);
 
+/**
+ * __iscsi_put_task - drop the refcount on a task
+ * @task: iscsi_task to drop the refcount on
+ *
+ * The back_lock must be held when calling in case it frees the task.
+ */
 void __iscsi_put_task(struct iscsi_task *task)
 {
 	if (refcount_dec_and_test(&task->refcount))
@@ -501,10 +507,11 @@ void iscsi_put_task(struct iscsi_task *task)
 {
 	struct iscsi_session *session = task->conn->session;
 
-	/* regular RX path uses back_lock */
-	spin_lock_bh(&session->back_lock);
-	__iscsi_put_task(task);
-	spin_unlock_bh(&session->back_lock);
+	if (refcount_dec_and_test(&task->refcount)) {
+		spin_lock_bh(&session->back_lock);
+		iscsi_free_task(task);
+		spin_unlock_bh(&session->back_lock);
+	}
 }
 EXPORT_SYMBOL_GPL(iscsi_put_task);
 
@@ -1454,8 +1461,6 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 {
 	int rc;
 
-	spin_lock_bh(&conn->session->back_lock);
-
 	if (!conn->task) {
 		/*
 		 * Take a ref so we can access it after xmit_task().
@@ -1464,7 +1469,6 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 		 * stopped the xmit thread.
 		 */
 		if (!iscsi_get_task(task)) {
-			spin_unlock_bh(&conn->session->back_lock);
 			WARN_ON_ONCE(1);
 			return 0;
 		}
@@ -1478,7 +1482,7 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 	 * case a bad target sends a cmd rsp before we have handled the task.
 	 */
 	if (was_requeue)
-		__iscsi_put_task(task);
+		iscsi_put_task(task);
 
 	/*
 	 * Do this after dropping the extra ref because if this was a requeue
@@ -1490,10 +1494,8 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 		 * task and get woken up again.
 		 */
 		conn->task = task;
-		spin_unlock_bh(&conn->session->back_lock);
 		return -ENODATA;
 	}
-	spin_unlock_bh(&conn->session->back_lock);
 
 	spin_unlock_bh(&conn->session->frwd_lock);
 	rc = conn->session->tt->xmit_task(task);
@@ -1501,10 +1503,7 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 	if (!rc) {
 		/* done with this task */
 		task->last_xfer = jiffies;
-	}
-	/* regular RX path uses back_lock */
-	spin_lock(&conn->session->back_lock);
-	if (rc) {
+	} else {
 		/*
 		 * get an extra ref that is released next time we access it
 		 * as conn->task above.
@@ -1513,8 +1512,7 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task,
 		conn->task = task;
 	}
 
-	__iscsi_put_task(task);
-	spin_unlock(&conn->session->back_lock);
+	iscsi_put_task(task);
 	return rc;
 }
 
-- 
2.25.1

[PATCH 9/9] scsi: libiscsi: Improve conn_send_pdu API

[Mike Christie]

The conn_send_pdu API is evil in that it returns a pointer to an
iscsi_task, but that task might have been freed already so you can't touch
it. This patch splits the task allocation and transmission, so functions
like iscsi_send_nopout() can access the task before its sent and do
whatever bookkeeping is needed before it is sent.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/libiscsi.c | 85 ++++++++++++++++++++++++++++++-----------
 include/scsi/libiscsi.h |  3 --
 2 files changed, 62 insertions(+), 26 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index da292761995f..b06ebbfe5de3 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -695,12 +695,18 @@ static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
 	return 0;
 }
 
+/**
+ * iscsi_alloc_mgmt_task - allocate and setup a mgmt task.
+ * @conn: iscsi conn that the task will be sent on.
+ * @hdr: iscsi pdu that will be sent.
+ * @data: buffer for data segment if needed.
+ * @data_size: length of data in bytes.
+ */
 static struct iscsi_task *
-__iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
+iscsi_alloc_mgmt_task(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		      char *data, uint32_t data_size)
 {
 	struct iscsi_session *session = conn->session;
-	struct iscsi_host *ihost = shost_priv(session->host);
 	uint8_t opcode = hdr->opcode & ISCSI_OPCODE_MASK;
 	struct iscsi_task *task;
 	itt_t itt;
@@ -781,28 +787,57 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 						   task->conn->session->age);
 	}
 
-	if (unlikely(READ_ONCE(conn->ping_task) == INVALID_SCSI_TASK))
-		WRITE_ONCE(conn->ping_task, task);
+	return task;
+
+free_task:
+	iscsi_put_task(task);
+	return NULL;
+}
+
+/**
+ * iscsi_send_mgmt_task - Send task created with iscsi_alloc_mgmt_task.
+ * @task: iscsi task to send.
+ *
+ * On failure this returns a non-zero error code, and the driver must free
+ * the task with iscsi_put_task;
+ */
+static int iscsi_send_mgmt_task(struct iscsi_task *task)
+{
+	struct iscsi_conn *conn = task->conn;
+	struct iscsi_session *session = conn->session;
+	struct iscsi_host *ihost = shost_priv(conn->session->host);
+	int rc = 0;
 
 	if (!ihost->workq) {
-		if (iscsi_prep_mgmt_task(conn, task))
-			goto free_task;
+		rc = iscsi_prep_mgmt_task(conn, task);
+		if (rc)
+			return rc;
 
-		if (session->tt->xmit_task(task))
-			goto free_task;
+		rc = session->tt->xmit_task(task);
+		if (rc)
+			return rc;
 	} else {
 		list_add_tail(&task->running, &conn->mgmtqueue);
 		iscsi_conn_queue_xmit(conn);
 	}
 
-	return task;
+	return 0;
+}
 
-free_task:
-	/* regular RX path uses back_lock */
-	spin_lock(&session->back_lock);
-	__iscsi_put_task(task);
-	spin_unlock(&session->back_lock);
-	return NULL;
+static int __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
+				 char *data, uint32_t data_size)
+{
+	struct iscsi_task *task;
+	int rc;
+
+	task = iscsi_alloc_mgmt_task(conn, hdr, data, data_size);
+	if (!task)
+		return -ENOMEM;
+
+	rc = iscsi_send_mgmt_task(task);
+	if (rc)
+		iscsi_put_task(task);
+	return rc;
 }
 
 int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
@@ -813,7 +848,7 @@ int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
 	int err = 0;
 
 	spin_lock_bh(&session->frwd_lock);
-	if (!__iscsi_conn_send_pdu(conn, hdr, data, data_size))
+	if (__iscsi_conn_send_pdu(conn, hdr, data, data_size))
 		err = -EPERM;
 	spin_unlock_bh(&session->frwd_lock);
 	return err;
@@ -986,7 +1021,6 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
 	if (!rhdr) {
 		if (READ_ONCE(conn->ping_task))
 			return -EINVAL;
-		WRITE_ONCE(conn->ping_task, INVALID_SCSI_TASK);
 	}
 
 	memset(&hdr, 0, sizeof(struct iscsi_nopout));
@@ -1000,10 +1034,18 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
 	} else
 		hdr.ttt = RESERVED_ITT;
 
-	task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)&hdr, NULL, 0);
-	if (!task) {
+	task = iscsi_alloc_mgmt_task(conn, (struct iscsi_hdr *)&hdr, NULL, 0);
+	if (!task)
+		return -ENOMEM;
+
+	if (!rhdr)
+		WRITE_ONCE(conn->ping_task, task);
+
+	if (iscsi_send_mgmt_task(task)) {
 		if (!rhdr)
 			WRITE_ONCE(conn->ping_task, NULL);
+		iscsi_put_task(task);
+
 		iscsi_conn_printk(KERN_ERR, conn, "Could not send nopout\n");
 		return -EIO;
 	} else if (!rhdr) {
@@ -1874,11 +1916,8 @@ static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
 	__must_hold(&session->frwd_lock)
 {
 	struct iscsi_session *session = conn->session;
-	struct iscsi_task *task;
 
-	task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)hdr,
-				      NULL, 0);
-	if (!task) {
+	if (__iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)hdr, NULL, 0)) {
 		spin_unlock_bh(&session->frwd_lock);
 		iscsi_conn_printk(KERN_ERR, conn, "Could not send TMF.\n");
 		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index cf7dfd61860f..b41b95655210 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -135,9 +135,6 @@ struct iscsi_task {
 	void			*dd_data;	/* driver/transport data */
 };
 
-/* invalid scsi_task pointer */
-#define	INVALID_SCSI_TASK	(struct iscsi_task *)-1l
-
 static inline int iscsi_task_has_unsol_data(struct iscsi_task *task)
 {
 	return task->unsol_r2t.data_length > task->unsol_r2t.sent;
-- 
2.25.1

Re: [PATCH 0/9] iscsi features for 5.20

[Martin K. Petersen]

Mike,

> The following patches are for 5.20. They were built against Linus's tree
> but they have no conflicts with the existing patches on the list and
> can be applied before or after those patches. The patches also apply over
> Martin's staging and queueing branches.
>
> The bulk of the patches allow us to run from a workqueue instead of always
> running from the net softirq. When using lots of sessions we see a nice
> perf bump when doing throughput and IOPs tests. There's then some cleanups
> and locking improvements.

Applied to 5.20/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH 0/9] iscsi features for 5.20

[Martin K. Petersen]

On Thu, 16 Jun 2022 17:45:48 -0500, Mike Christie wrote:

> The following patches are for 5.20. They were built against Linus's tree
> but they have no conflicts with the existing patches on the list and
> can be applied before or after those patches. The patches also apply over
> Martin's staging and queueing branches.
> 
> The bulk of the patches allow us to run from a workqueue instead of always
> running from the net softirq. When using lots of sessions we see a nice
> perf bump when doing throughput and IOPs tests. There's then some cleanups
> and locking improvements.
> 
> [...]

Applied to 5.20/scsi-queue, thanks!

[1/9] scsi: iscsi: Rename iscsi_conn_queue_work()
      https://git.kernel.org/mkp/scsi/c/4b9f8ce4d5e8
[2/9] scsi: iscsi: Add recv workqueue helpers
      https://git.kernel.org/mkp/scsi/c/8af809966c0b
[3/9] scsi: iscsi: Run recv path from workqueue
      https://git.kernel.org/mkp/scsi/c/f1d269765ee2
[4/9] scsi: iscsi_tcp: Tell net when there's more data
      https://git.kernel.org/mkp/scsi/c/f93a722fa7b3
[5/9] scsi: iscsi_tcp: Drop target_alloc use
      https://git.kernel.org/mkp/scsi/c/9b89153680f6
[6/9] scsi: iscsi: Remove unneeded task state check
      https://git.kernel.org/mkp/scsi/c/533ac412fdb4
[7/9] scsi: iscsi: Remove iscsi_get_task back_lock requirement
      https://git.kernel.org/mkp/scsi/c/e1c6a7ec1429
[8/9] scsi: iscsi: Try to avoid taking back_lock in xmit path
      https://git.kernel.org/mkp/scsi/c/6d626150d6d1
[9/9] scsi: libiscsi: Improve conn_send_pdu API
      https://git.kernel.org/mkp/scsi/c/6e637b723d82

-- 
Martin K. Petersen	Oracle Linux Engineering