1 files changed, 138 insertions, 0 deletions
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
new file mode 100644
index 000000000..cfaf5a1d4
--- /dev/null
+++ b/include/linux/trace_seq.h
@@ -0,0 +1,138 @@
+#ifndef _LINUX_TRACE_SEQ_H
+#define _LINUX_TRACE_SEQ_H
+
+#include <linux/seq_buf.h>
+
+#include <asm/page.h>
+
+/*
+ * Trace sequences are used to allow a function to call several other functions
+ * to create a string of data to use (up to a max of PAGE_SIZE).
+ */
+
+struct trace_seq {
+	unsigned char		buffer[PAGE_SIZE];
+	struct seq_buf		seq;
+	int			full;
+};
+
+static inline void
+trace_seq_init(struct trace_seq *s)
+{
+	seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
+	s->full = 0;
+}
+
+/**
+ * trace_seq_used - amount of actual data written to buffer
+ * @s: trace sequence descriptor
+ *
+ * Returns the amount of data written to the buffer.
+ *
+ * IMPORTANT!
+ *
+ * Use this instead of @s->seq.len if you need to pass the amount
+ * of data from the buffer to another buffer (userspace, or what not).
+ * The @s->seq.len on overflow is bigger than the buffer size and
+ * using it can cause access to undefined memory.
+ */
+static inline int trace_seq_used(struct trace_seq *s)
+{
+	return seq_buf_used(&s->seq);
+}
+
+/**
+ * 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 + seq_buf_used(&s->seq);
+}
+
+/**
+ * trace_seq_has_overflowed - return true if the trace_seq took too much
+ * @s: trace sequence descriptor
+ *
+ * Returns true if too much data was added to the trace_seq and it is
+ * now full and will not take anymore.
+ */
+static inline bool trace_seq_has_overflowed(struct trace_seq *s)
+{
+	return s->full || seq_buf_has_overflowed(&s->seq);
+}
+
+/*
+ * Currently only defined when tracing is enabled.
+ */
+#ifdef CONFIG_TRACING
+extern __printf(2, 3)
+void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
+extern __printf(2, 0)
+void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
+extern void
+trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
+extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
+extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
+			     int cnt);
+extern void trace_seq_puts(struct trace_seq *s, const char *str);
+extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
+extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
+extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
+				unsigned int len);
+extern int trace_seq_path(struct trace_seq *s, const struct path *path);
+
+extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
+			     int nmaskbits);
+
+#else /* CONFIG_TRACING */
+static inline void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
+{
+}
+static inline void
+trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
+{
+}
+
+static inline void
+trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
+		  int nmaskbits)
+{
+}
+
+static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
+{
+	return 0;
+}
+static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
+				    int cnt)
+{
+	return 0;
+}
+static inline void trace_seq_puts(struct trace_seq *s, const char *str)
+{
+}
+static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
+{
+}
+static inline void
+trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
+{
+}
+static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
+				       unsigned int len)
+{
+}
+static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
+{
+	return 0;
+}
+#endif /* CONFIG_TRACING */
+
+#endif /* _LINUX_TRACE_SEQ_H */