[for-next][PATCH 13/21] tracing: Add trace_seq_buffer_ptr() helper function

Steven Rostedt
2014-07-03T16:12:31Z

[-- Attachment #1: 0013-tracing-Add-trace_seq_buffer_ptr-helper-function.patch --]
[-- Type: text/plain, Size: 6941 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

There's several locations in the kernel that open code the calculation
of the next location in the trace_seq buffer. This is usually done with

p->buffer + p->len

Instead of having this open coded, supply a helper function in the
header to do it for them. This function is called trace_seq_buffer_ptr().

Link: http://lkml.kernel.org/p/20140626220129.452783019@goodmis.org

Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
arch/x86/kvm/mmutrace.h | 2 +-
drivers/scsi/scsi_trace.c | 16 ++++++++--------
include/linux/trace_seq.h | 15 +++++++++++++++
kernel/trace/trace_output.c | 14 +++++++-------
4 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h
index 9d2e0ffcb190..2e5652b62fd6 100644
--- a/arch/x86/kvm/mmutrace.h
+++ b/arch/x86/kvm/mmutrace.h
@@ -22,7 +22,7 @@
__entry->unsync = sp->unsync;

#define KVM_MMU_PAGE_PRINTK() ({ \
- const char *ret = p->buffer + p->len; \
+ const char *ret = trace_seq_buffer_ptr(p); \
static const char *access_str[] = { \
"---", "--x", "w--", "w-x", "-u-", "-ux", "wu-", "wux" \
}; \
diff --git a/drivers/scsi/scsi_trace.c b/drivers/scsi/scsi_trace.c
index 2bea4f0b684a..503594e5f76d 100644
--- a/drivers/scsi/scsi_trace.c
+++ b/drivers/scsi/scsi_trace.c
@@ -28,7 +28,7 @@ scsi_trace_misc(struct trace_seq *, unsigned char *, int);
static const char *
scsi_trace_rw6(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
sector_t lba = 0, txlen = 0;

lba |= ((cdb[1] & 0x1F) << 16);
@@ -46,7 +46,7 @@ scsi_trace_rw6(struct trace_seq *p, unsigned char *cdb, int len)
static const char *
scsi_trace_rw10(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
sector_t lba = 0, txlen = 0;

lba |= (cdb[2] << 24);
@@ -71,7 +71,7 @@ scsi_trace_rw10(struct trace_seq *p, unsigned char *cdb, int len)
static const char *
scsi_trace_rw12(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
sector_t lba = 0, txlen = 0;

lba |= (cdb[2] << 24);
@@ -94,7 +94,7 @@ scsi_trace_rw12(struct trace_seq *p, unsigned char *cdb, int len)
static const char *
scsi_trace_rw16(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
sector_t lba = 0, txlen = 0;

lba |= ((u64)cdb[2] << 56);
@@ -125,7 +125,7 @@ scsi_trace_rw16(struct trace_seq *p, unsigned char *cdb, int len)
static const char *
scsi_trace_rw32(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len, *cmd;
+ const char *ret = trace_seq_buffer_ptr(p), *cmd;
sector_t lba = 0, txlen = 0;
u32 ei_lbrt = 0;

@@ -180,7 +180,7 @@ out:
static const char *
scsi_trace_unmap(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
unsigned int regions = cdb[7] << 8 | cdb[8];

trace_seq_printf(p, "regions=%u", (regions - 8) / 16);
@@ -192,7 +192,7 @@ scsi_trace_unmap(struct trace_seq *p, unsigned char *cdb, int len)
static const char *
scsi_trace_service_action_in(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len, *cmd;
+ const char *ret = trace_seq_buffer_ptr(p), *cmd;
sector_t lba = 0;
u32 alloc_len = 0;

@@ -247,7 +247,7 @@ scsi_trace_varlen(struct trace_seq *p, unsigned char *cdb, int len)
static const char *
scsi_trace_misc(struct trace_seq *p, unsigned char *cdb, int len)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);

trace_seq_printf(p, "-");
trace_seq_putc(p, 0);
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index dd85753e1bb0..ea6c9dea79e3 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -25,6 +25,21 @@ trace_seq_init(struct trace_seq *s)
s->full = 0;
}

+/**
+ * trace_seq_buffer_ptr - return pointer to next location in buffer
+ * @s: trace sequence descriptor
+ *
+ * Returns the pointer to the buffer where the next write to
+ * the buffer will happen. This is useful to save the location
+ * that is about to be written to and then return the result
+ * of that write.
+ */
+static inline unsigned char *
+trace_seq_buffer_ptr(struct trace_seq *s)
+{
+ return s->buffer + s->len;
+}
+
/*
* Currently only defined when tracing is enabled.
*/
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index b8930f79a04b..c6977d5a9b12 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -75,7 +75,7 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
{
unsigned long mask;
const char *str;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
int i, first = 1;

for (i = 0; flag_array[i].name && flags; i++) {
@@ -111,7 +111,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
const struct trace_print_flags *symbol_array)
{
int i;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);

for (i = 0; symbol_array[i].name; i++) {

@@ -122,7 +122,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
break;
}

- if (ret == (const char *)(p->buffer + p->len))
+ if (ret == (const char *)(trace_seq_buffer_ptr(p)))
trace_seq_printf(p, "0x%lx", val);

trace_seq_putc(p, 0);
@@ -137,7 +137,7 @@ ftrace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
const struct trace_print_flags_u64 *symbol_array)
{
int i;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);

for (i = 0; symbol_array[i].name; i++) {

@@ -148,7 +148,7 @@ ftrace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
break;
}

- if (ret == (const char *)(p->buffer + p->len))
+ if (ret == (const char *)(trace_seq_buffer_ptr(p)))
trace_seq_printf(p, "0x%llx", val);

trace_seq_putc(p, 0);
@@ -162,7 +162,7 @@ const char *
ftrace_print_bitmask_seq(struct trace_seq *p, void *bitmask_ptr,
unsigned int bitmask_size)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);

trace_seq_bitmask(p, bitmask_ptr, bitmask_size * 8);
trace_seq_putc(p, 0);
@@ -175,7 +175,7 @@ const char *
ftrace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int buf_len)
{
int i;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);

for (i = 0; i < buf_len; i++)
trace_seq_printf(p, "%s%2.2x", i == 0 ? "" : " ", buf[i]);
--
2.0.0