nvmet: introduce target-side trace

This patch introduces target-side request tracing. As Christoph
suggested, the trace would not be in a core or module to avoid
disadvantages like cache miss:
http://lists.infradead.org/pipermail/linux-nvme/2019-June/024721.html

The target-side trace code is entirely based on the Johannes's trace code
from the host side. It has lots of codes duplicated, but it would be
better than having advantages mentioned above.

It also traces not only fabrics commands, but also nvme normal commands.
Once the codes to be shared gets bigger, then we can make it common as
suggsted.

This also removed the create_sq and create_cq trace parsing functions
because it will be done by the connect fabrics command.

Example:
echo 1 > /sys/kernel/debug/tracing/event/nvmet/nvmet_req_init/enable
echo 1 > /sys/kernel/debug/tracing/event/nvmet/nvmet_req_complete/enable
cat /sys/kernel/debug/tracing/trace

Signed-off-by: Minwoo Im <[e-mail]>
[hch: fixed the symbol namespace and a an endianess conversion]
Signed-off-by: Christoph Hellwig <[e-mail]>

drivers/nvme/target/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 
+ccflags-y				+= -I$(src)
+
 obj-$(CONFIG_NVME_TARGET)		+= nvmet.o
 obj-$(CONFIG_NVME_TARGET_LOOP)		+= nvme-loop.o
 obj-$(CONFIG_NVME_TARGET_RDMA)		+= nvmet-rdma.o
···
 nvmet-fc-y	+= fc.o
 nvme-fcloop-y	+= fcloop.o
 nvmet-tcp-y	+= tcp.o
+nvmet-$(CONFIG_TRACING)	+= trace.o

drivers/nvme/target/core.c

···
 #include <linux/pci-p2pdma.h>
 #include <linux/scatterlist.h>
 
+#define CREATE_TRACE_POINTS
+#include "trace.h"
+
 #include "nvmet.h"
 
 struct workqueue_struct *buffered_io_wq;
···
 
 	if (unlikely(status))
 		nvmet_set_error(req, status);
+
+	trace_nvmet_req_complete(req);
+
 	if (req->ns)
 		nvmet_put_namespace(req->ns);
 	req->ops->queue_response(req);
···
 	req->ns = NULL;
 	req->error_loc = NVMET_NO_ERROR_LOC;
 	req->error_slba = 0;
+
+	trace_nvmet_req_init(req, req->cmd);
 
 	/* no support for fused commands yet */
 	if (unlikely(flags & (NVME_CMD_FUSE_FIRST | NVME_CMD_FUSE_SECOND))) {

drivers/nvme/target/trace.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NVM Express target device driver tracepoints
+ * Copyright (c) 2018 Johannes Thumshirn, SUSE Linux GmbH
+ */
+
+#include <asm/unaligned.h>
+#include "trace.h"
+
+static const char *nvmet_trace_admin_identify(struct trace_seq *p, u8 *cdw10)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+	u8 cns = cdw10[0];
+	u16 ctrlid = get_unaligned_le16(cdw10 + 2);
+
+	trace_seq_printf(p, "cns=%u, ctrlid=%u", cns, ctrlid);
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+
+static const char *nvmet_trace_admin_get_features(struct trace_seq *p,
+						 u8 *cdw10)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+	u8 fid = cdw10[0];
+	u8 sel = cdw10[1] & 0x7;
+	u32 cdw11 = get_unaligned_le32(cdw10 + 4);
+
+	trace_seq_printf(p, "fid=0x%x sel=0x%x cdw11=0x%x", fid, sel, cdw11);
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+
+static const char *nvmet_trace_read_write(struct trace_seq *p, u8 *cdw10)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+	u64 slba = get_unaligned_le64(cdw10);
+	u16 length = get_unaligned_le16(cdw10 + 8);
+	u16 control = get_unaligned_le16(cdw10 + 10);
+	u32 dsmgmt = get_unaligned_le32(cdw10 + 12);
+	u32 reftag = get_unaligned_le32(cdw10 +  16);
+
+	trace_seq_printf(p,
+			 "slba=%llu, len=%u, ctrl=0x%x, dsmgmt=%u, reftag=%u",
+			 slba, length, control, dsmgmt, reftag);
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+
+static const char *nvmet_trace_dsm(struct trace_seq *p, u8 *cdw10)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+
+	trace_seq_printf(p, "nr=%u, attributes=%u",
+			 get_unaligned_le32(cdw10),
+			 get_unaligned_le32(cdw10 + 4));
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+
+static const char *nvmet_trace_common(struct trace_seq *p, u8 *cdw10)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+
+	trace_seq_printf(p, "cdw10=%*ph", 24, cdw10);
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+
+const char *nvmet_trace_parse_admin_cmd(struct trace_seq *p,
+		u8 opcode, u8 *cdw10)
+{
+	switch (opcode) {
+	case nvme_admin_identify:
+		return nvmet_trace_admin_identify(p, cdw10);
+	case nvme_admin_get_features:
+		return nvmet_trace_admin_get_features(p, cdw10);
+	default:
+		return nvmet_trace_common(p, cdw10);
+	}
+}
+
+const char *nvmet_trace_parse_nvm_cmd(struct trace_seq *p,
+		u8 opcode, u8 *cdw10)
+{
+	switch (opcode) {
+	case nvme_cmd_read:
+	case nvme_cmd_write:
+	case nvme_cmd_write_zeroes:
+		return nvmet_trace_read_write(p, cdw10);
+	case nvme_cmd_dsm:
+		return nvmet_trace_dsm(p, cdw10);
+	default:
+		return nvmet_trace_common(p, cdw10);
+	}
+}
+
+static const char *nvmet_trace_fabrics_property_set(struct trace_seq *p,
+		u8 *spc)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+	u8 attrib = spc[0];
+	u32 ofst = get_unaligned_le32(spc + 4);
+	u64 value = get_unaligned_le64(spc + 8);
+
+	trace_seq_printf(p, "attrib=%u, ofst=0x%x, value=0x%llx",
+			 attrib, ofst, value);
+	trace_seq_putc(p, 0);
+	return ret;
+}
+
+static const char *nvmet_trace_fabrics_connect(struct trace_seq *p,
+		u8 *spc)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+	u16 recfmt = get_unaligned_le16(spc);
+	u16 qid = get_unaligned_le16(spc + 2);
+	u16 sqsize = get_unaligned_le16(spc + 4);
+	u8 cattr = spc[6];
+	u32 kato = get_unaligned_le32(spc + 8);
+
+	trace_seq_printf(p, "recfmt=%u, qid=%u, sqsize=%u, cattr=%u, kato=%u",
+			 recfmt, qid, sqsize, cattr, kato);
+	trace_seq_putc(p, 0);
+	return ret;
+}
+
+static const char *nvmet_trace_fabrics_property_get(struct trace_seq *p,
+		u8 *spc)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+	u8 attrib = spc[0];
+	u32 ofst = get_unaligned_le32(spc + 4);
+
+	trace_seq_printf(p, "attrib=%u, ofst=0x%x", attrib, ofst);
+	trace_seq_putc(p, 0);
+	return ret;
+}
+
+static const char *nvmet_trace_fabrics_common(struct trace_seq *p, u8 *spc)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+
+	trace_seq_printf(p, "spcecific=%*ph", 24, spc);
+	trace_seq_putc(p, 0);
+	return ret;
+}
+
+const char *nvmet_trace_parse_fabrics_cmd(struct trace_seq *p,
+		u8 fctype, u8 *spc)
+{
+	switch (fctype) {
+	case nvme_fabrics_type_property_set:
+		return nvmet_trace_fabrics_property_set(p, spc);
+	case nvme_fabrics_type_connect:
+		return nvmet_trace_fabrics_connect(p, spc);
+	case nvme_fabrics_type_property_get:
+		return nvmet_trace_fabrics_property_get(p, spc);
+	default:
+		return nvmet_trace_fabrics_common(p, spc);
+	}
+}
+
+const char *nvmet_trace_disk_name(struct trace_seq *p, char *name)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+
+	if (*name)
+		trace_seq_printf(p, "disk=%s, ", name);
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+
+const char *nvmet_trace_ctrl_name(struct trace_seq *p, struct nvmet_ctrl *ctrl)
+{
+	const char *ret = trace_seq_buffer_ptr(p);
+
+	/*
+	 * XXX: We don't know the controller instance before executing the
+	 * connect command itself because the connect command for the admin
+	 * queue will not provide the cntlid which will be allocated in this
+	 * command.  In case of io queues, the controller instance will be
+	 * mapped by the extra data of the connect command.
+	 * If we can know the extra data of the connect command in this stage,
+	 * we can update this print statement later.
+	 */
+	if (ctrl)
+		trace_seq_printf(p, "%d", ctrl->cntlid);
+	else
+		trace_seq_printf(p, "_");
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+

drivers/nvme/target/trace.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * NVM Express target device driver tracepoints
+ * Copyright (c) 2018 Johannes Thumshirn, SUSE Linux GmbH
+ *
+ * This is entirely based on drivers/nvme/host/trace.h
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM nvmet
+
+#if !defined(_TRACE_NVMET_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_NVMET_H
+
+#include <linux/nvme.h>
+#include <linux/tracepoint.h>
+#include <linux/trace_seq.h>
+
+#include "nvmet.h"
+
+const char *nvmet_trace_parse_admin_cmd(struct trace_seq *p, u8 opcode,
+		u8 *cdw10);
+const char *nvmet_trace_parse_nvm_cmd(struct trace_seq *p, u8 opcode,
+		u8 *cdw10);
+const char *nvmet_trace_parse_fabrics_cmd(struct trace_seq *p, u8 fctype,
+		u8 *spc);
+
+#define parse_nvme_cmd(qid, opcode, fctype, cdw10)			\
+	((opcode) == nvme_fabrics_command ?				\
+	 nvmet_trace_parse_fabrics_cmd(p, fctype, cdw10) :		\
+	(qid ?								\
+	 nvmet_trace_parse_nvm_cmd(p, opcode, cdw10) :			\
+	 nvmet_trace_parse_admin_cmd(p, opcode, cdw10)))
+
+const char *nvmet_trace_ctrl_name(struct trace_seq *p, struct nvmet_ctrl *ctrl);
+#define __print_ctrl_name(ctrl)				\
+	nvmet_trace_ctrl_name(p, ctrl)
+
+const char *nvmet_trace_disk_name(struct trace_seq *p, char *name);
+#define __print_disk_name(name)				\
+	nvmet_trace_disk_name(p, name)
+
+#ifndef TRACE_HEADER_MULTI_READ
+static inline struct nvmet_ctrl *nvmet_req_to_ctrl(struct nvmet_req *req)
+{
+	return req->sq->ctrl;
+}
+
+static inline void __assign_disk_name(char *name, struct nvmet_req *req,
+		bool init)
+{
+	struct nvmet_ctrl *ctrl = nvmet_req_to_ctrl(req);
+	struct nvmet_ns *ns;
+
+	if ((init && req->sq->qid) || (!init && req->cq->qid)) {
+		ns = nvmet_find_namespace(ctrl, req->cmd->rw.nsid);
+		strncpy(name, ns->device_path, DISK_NAME_LEN);
+		return;
+	}
+
+	memset(name, 0, DISK_NAME_LEN);
+}
+#endif
+
+TRACE_EVENT(nvmet_req_init,
+	TP_PROTO(struct nvmet_req *req, struct nvme_command *cmd),
+	TP_ARGS(req, cmd),
+	TP_STRUCT__entry(
+		__field(struct nvme_command *, cmd)
+		__field(struct nvmet_ctrl *, ctrl)
+		__array(char, disk, DISK_NAME_LEN)
+		__field(int, qid)
+		__field(u16, cid)
+		__field(u8, opcode)
+		__field(u8, fctype)
+		__field(u8, flags)
+		__field(u32, nsid)
+		__field(u64, metadata)
+		__array(u8, cdw10, 24)
+	),
+	TP_fast_assign(
+		__entry->cmd = cmd;
+		__entry->ctrl = nvmet_req_to_ctrl(req);
+		__assign_disk_name(__entry->disk, req, true);
+		__entry->qid = req->sq->qid;
+		__entry->cid = cmd->common.command_id;
+		__entry->opcode = cmd->common.opcode;
+		__entry->fctype = cmd->fabrics.fctype;
+		__entry->flags = cmd->common.flags;
+		__entry->nsid = le32_to_cpu(cmd->common.nsid);
+		__entry->metadata = le64_to_cpu(cmd->common.metadata);
+		memcpy(__entry->cdw10, &cmd->common.cdw10,
+			sizeof(__entry->cdw10));
+	),
+	TP_printk("nvmet%s: %sqid=%d, cmdid=%u, nsid=%u, flags=%#x, "
+		  "meta=%#llx, cmd=(%s, %s)",
+		__print_ctrl_name(__entry->ctrl),
+		__print_disk_name(__entry->disk),
+		__entry->qid, __entry->cid, __entry->nsid,
+		__entry->flags, __entry->metadata,
+		show_opcode_name(__entry->qid, __entry->opcode,
+				__entry->fctype),
+		parse_nvme_cmd(__entry->qid, __entry->opcode,
+				__entry->fctype, __entry->cdw10))
+);
+
+TRACE_EVENT(nvmet_req_complete,
+	TP_PROTO(struct nvmet_req *req),
+	TP_ARGS(req),
+	TP_STRUCT__entry(
+		__field(struct nvmet_ctrl *, ctrl)
+		__array(char, disk, DISK_NAME_LEN)
+		__field(int, qid)
+		__field(int, cid)
+		__field(u64, result)
+		__field(u16, status)
+	),
+	TP_fast_assign(
+		__entry->ctrl = nvmet_req_to_ctrl(req);
+		__entry->qid = req->cq->qid;
+		__entry->cid = req->cqe->command_id;
+		__entry->result = le64_to_cpu(req->cqe->result.u64);
+		__entry->status = le16_to_cpu(req->cqe->status) >> 1;
+		__assign_disk_name(__entry->disk, req, false);
+	),
+	TP_printk("nvmet%s: %sqid=%d, cmdid=%u, res=%#llx, status=%#x",
+		__print_ctrl_name(__entry->ctrl),
+		__print_disk_name(__entry->disk),
+		__entry->qid, __entry->cid, __entry->result, __entry->status)
+
+);
+
+#endif /* _TRACE_NVMET_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>