[SCSI] fnic: Fnic Trace Utility

Fnic Trace utility is a tracing functionality built directly into fnic driver
to trace events. The benefit that trace buffer brings to fnic driver is the
ability to see what it happening inside the fnic driver. It also provides the
capability to trace every IO event inside fnic driver to debug panics, hangs
and potentially IO corruption issues. This feature makes it easy to find
problems in fnic driver and it also helps in tracking down strange bugs in a
more manageable way. Trace buffer is shared across all fnic instances for
this implementation.

Signed-off-by: Hiral Patel <hiralpat@cisco.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/drivers/scsi/fnic/fnic_trace.h b/drivers/scsi/fnic/fnic_trace.h
new file mode 100644
index 000000000000..cef42b4c4d6c
--- /dev/null
+++ b/drivers/scsi/fnic/fnic_trace.h
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2012 Cisco Systems, Inc.  All rights reserved.
+ *
+ * This program is free software; you may redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef __FNIC_TRACE_H__
+#define __FNIC_TRACE_H__
+
+#define FNIC_ENTRY_SIZE_BYTES 64
+
+extern ssize_t simple_read_from_buffer(void __user *to,
+					  size_t count,
+					  loff_t *ppos,
+					  const void *from,
+					  size_t available);
+
+extern unsigned int fnic_trace_max_pages;
+extern int fnic_tracing_enabled;
+extern unsigned int trace_max_pages;
+
+typedef struct fnic_trace_dbg {
+	int wr_idx;
+	int rd_idx;
+	unsigned long *page_offset;
+} fnic_trace_dbg_t;
+
+typedef struct fnic_dbgfs {
+	int buffer_len;
+	char *buffer;
+} fnic_dbgfs_t;
+
+struct fnic_trace_data {
+	union {
+		struct {
+			u32 low;
+			u32 high;
+		};
+		u64 val;
+	} timestamp, fnaddr;
+	u32 host_no;
+	u32 tag;
+	u64 data[5];
+} __attribute__((__packed__));
+
+typedef struct fnic_trace_data fnic_trace_data_t;
+
+#define FNIC_TRACE_ENTRY_SIZE \
+		  (FNIC_ENTRY_SIZE_BYTES - sizeof(fnic_trace_data_t))
+
+#define FNIC_TRACE(_fn, _hn, _t, _a, _b, _c, _d, _e)           \
+	if (unlikely(fnic_tracing_enabled)) {                   \
+		fnic_trace_data_t *trace_buf = fnic_trace_get_buf(); \
+		if (trace_buf) { \
+			if (sizeof(unsigned long) < 8) { \
+				trace_buf->timestamp.low = jiffies; \
+				trace_buf->fnaddr.low = (u32)(unsigned long)_fn; \
+			} else { \
+				trace_buf->timestamp.val = jiffies; \
+				trace_buf->fnaddr.val = (u64)(unsigned long)_fn; \
+			} \
+			trace_buf->host_no = _hn; \
+			trace_buf->tag = _t; \
+			trace_buf->data[0] = (u64)(unsigned long)_a; \
+			trace_buf->data[1] = (u64)(unsigned long)_b; \
+			trace_buf->data[2] = (u64)(unsigned long)_c; \
+			trace_buf->data[3] = (u64)(unsigned long)_d; \
+			trace_buf->data[4] = (u64)(unsigned long)_e; \
+		} \
+	}
+
+fnic_trace_data_t *fnic_trace_get_buf(void);
+int fnic_get_trace_data(fnic_dbgfs_t *);
+int fnic_trace_buf_init(void);
+void fnic_trace_free(void);
+int fnic_trace_debugfs_init(void);
+void fnic_trace_debugfs_terminate(void);
+
+#endif