tracing: Create seq_buf layer in trace_seq

Create a seq_buf layer that trace_seq sits on. The seq_buf will not
be limited to page size. This will allow other usages of seq_buf
instead of a hard set PAGE_SIZE one that trace_seq has.

Link: http://lkml.kernel.org/r/20141104160221.864997179@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

6 files changed, 452 insertions, 119 deletions

diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 67d6369ddf83..edc98c72a634 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
 obj-$(CONFIG_TRACING) += trace.o
 obj-$(CONFIG_TRACING) += trace_output.o
 obj-$(CONFIG_TRACING) += trace_seq.o
+obj-$(CONFIG_TRACING) += seq_buf.o
 obj-$(CONFIG_TRACING) += trace_stat.o
 obj-$(CONFIG_TRACING) += trace_printk.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
new file mode 100644
index 000000000000..e9a7861595d2
--- /dev/null
+++ b/kernel/trace/seq_buf.c
@@ -0,0 +1,341 @@
+/*
+ * seq_buf.c
+ *
+ * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * The seq_buf is a handy tool that allows you to pass a descriptor around
+ * to a buffer that other functions can write to. It is similar to the
+ * seq_file functionality but has some differences.
+ *
+ * To use it, the seq_buf must be initialized with seq_buf_init().
+ * This will set up the counters within the descriptor. You can call
+ * seq_buf_init() more than once to reset the seq_buf to start
+ * from scratch.
+ */
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/seq_buf.h>
+
+/* How much buffer is written? */
+#define SEQ_BUF_USED(s) min((s)->len, (s)->size - 1)
+
+/**
+ * seq_buf_print_seq - move the contents of seq_buf into a seq_file
+ * @m: the seq_file descriptor that is the destination
+ * @s: the seq_buf descriptor that is the source.
+ *
+ * Returns zero on success, non zero otherwise
+ */
+int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
+{
+        unsigned int len = SEQ_BUF_USED(s);
+
+        return seq_write(m, s->buffer, len);
+}
+
+/**
+ * seq_buf_vprintf - sequence printing of information.
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ * @args: va_list of arguments from a printf() type function
+ *
+ * Writes a vnprintf() format into the sequencce buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
+{
+        int len;
+
+        WARN_ON(s->size == 0);
+
+        if (s->len < s->size) {
+                len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
+                if (s->len + len < s->size) {
+                        s->len += len;
+                        return 0;
+                }
+        }
+        seq_buf_set_overflow(s);
+        return -1;
+}
+
+/**
+ * seq_buf_printf - sequence printing of information
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ *
+ * Writes a printf() format into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
+{
+        va_list ap;
+        int ret;
+
+        va_start(ap, fmt);
+        ret = seq_buf_vprintf(s, fmt, ap);
+        va_end(ap);
+
+        return ret;
+}
+
+/**
+ * seq_buf_bitmask - write a bitmask array in its ASCII representation
+ * @s:          seq_buf descriptor
+ * @maskp:      points to an array of unsigned longs that represent a bitmask
+ * @nmaskbits:  The number of bits that are valid in @maskp
+ *
+ * Writes a ASCII representation of a bitmask string into @s.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+                    int nmaskbits)
+{
+        unsigned int len = seq_buf_buffer_left(s);
+        int ret;
+
+        WARN_ON(s->size == 0);
+
+        /*
+         * The last byte of the buffer is used to determine if we
+         * overflowed or not.
+         */
+        if (len > 1) {
+                ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
+                if (ret < len) {
+                        s->len += ret;
+                        return 0;
+                }
+        }
+        seq_buf_set_overflow(s);
+        return -1;
+}
+
+/**
+ * seq_buf_bprintf - Write the printf string from binary arguments
+ * @s: seq_buf descriptor
+ * @fmt: The format string for the @binary arguments
+ * @binary: The binary arguments for @fmt.
+ *
+ * When recording in a fast path, a printf may be recorded with just
+ * saving the format and the arguments as they were passed to the
+ * function, instead of wasting cycles converting the arguments into
+ * ASCII characters. Instead, the arguments are saved in a 32 bit
+ * word array that is defined by the format string constraints.
+ *
+ * This function will take the format and the binary array and finish
+ * the conversion into the ASCII string within the buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
+{
+        unsigned int len = seq_buf_buffer_left(s);
+        int ret;
+
+        WARN_ON(s->size == 0);
+
+        if (s->len < s->size) {
+                ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+                if (s->len + ret < s->size) {
+                        s->len += ret;
+                        return 0;
+                }
+        }
+        seq_buf_set_overflow(s);
+        return -1;
+}
+
+/**
+ * seq_buf_puts - sequence printing of simple string
+ * @s: seq_buf descriptor
+ * @str: simple string to record
+ *
+ * Copy a simple string into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_puts(struct seq_buf *s, const char *str)
+{
+        unsigned int len = strlen(str);
+
+        WARN_ON(s->size == 0);
+
+        if (s->len + len < s->size) {
+                memcpy(s->buffer + s->len, str, len);
+                s->len += len;
+                return 0;
+        }
+        seq_buf_set_overflow(s);
+        return -1;
+}
+
+/**
+ * seq_buf_putc - sequence printing of simple character
+ * @s: seq_buf descriptor
+ * @c: simple character to record
+ *
+ * Copy a single character into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putc(struct seq_buf *s, unsigned char c)
+{
+        WARN_ON(s->size == 0);
+
+        if (s->len + 1 < s->size) {
+                s->buffer[s->len++] = c;
+                return 0;
+        }
+        seq_buf_set_overflow(s);
+        return -1;
+}
+
+/**
+ * seq_buf_putmem - write raw data into the sequenc buffer
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to copy into the buffer
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * There may be cases where raw memory needs to be written into the
+ * buffer and a strcpy() would not work. Using this function allows
+ * for such cases.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
+{
+        WARN_ON(s->size == 0);
+
+        if (s->len + len < s->size) {
+                memcpy(s->buffer + s->len, mem, len);
+                s->len += len;
+                return 0;
+        }
+        seq_buf_set_overflow(s);
+        return -1;
+}
+
+#define MAX_MEMHEX_BYTES        8U
+#define HEX_CHARS               (MAX_MEMHEX_BYTES*2 + 1)
+
+/**
+ * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to write its hex ASCII representation of
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * This is similar to seq_buf_putmem() except instead of just copying the
+ * raw memory into the buffer it writes its ASCII representation of it
+ * in hex characters.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+                       unsigned int len)
+{
+        unsigned char hex[HEX_CHARS];
+        const unsigned char *data = mem;
+        unsigned int start_len;
+        int i, j;
+
+        WARN_ON(s->size == 0);
+
+        while (len) {
+                start_len = min(len, HEX_CHARS - 1);
+#ifdef __BIG_ENDIAN
+                for (i = 0, j = 0; i < start_len; i++) {
+#else
+                for (i = start_len-1, j = 0; i >= 0; i--) {
+#endif
+                        hex[j++] = hex_asc_hi(data[i]);
+                        hex[j++] = hex_asc_lo(data[i]);
+                }
+                if (WARN_ON_ONCE(j == 0 || j/2 > len))
+                        break;
+
+                /* j increments twice per loop */
+                len -= j / 2;
+                hex[j++] = ' ';
+
+                seq_buf_putmem(s, hex, j);
+                if (seq_buf_has_overflowed(s))
+                        return -1;
+        }
+        return 0;
+}
+
+/**
+ * seq_buf_path - copy a path into the sequence buffer
+ * @s: seq_buf descriptor
+ * @path: path to write into the sequence buffer.
+ *
+ * Write a path name into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_path(struct seq_buf *s, const struct path *path)
+{
+        unsigned int len = seq_buf_buffer_left(s);
+        unsigned char *p;
+
+        WARN_ON(s->size == 0);
+
+        p = d_path(path, s->buffer + s->len, len);
+        if (!IS_ERR(p)) {
+                p = mangle_path(s->buffer + s->len, p, "\n");
+                if (p) {
+                        s->len = p - s->buffer;
+                        return 0;
+                }
+        }
+        seq_buf_set_overflow(s);
+        return -1;
+}
+
+/**
+ * seq_buf_to_user - copy the squence buffer to user space
+ * @s: seq_buf descriptor
+ * @ubuf: The userspace memory location to copy to
+ * @cnt: The amount to copy
+ *
+ * Copies the sequence buffer into the userspace memory pointed to
+ * by @ubuf. It starts from the last read position (@s->readpos)
+ * and writes up to @cnt characters or till it reaches the end of
+ * the content in the buffer (@s->len), which ever comes first.
+ *
+ * On success, it returns a positive number of the number of bytes
+ * it copied.
+ *
+ * On failure it returns -EBUSY if all of the content in the
+ * sequence has been already read, which includes nothing in the
+ * sequence (@s->len == @s->readpos).
+ *
+ * Returns -EFAULT if the copy to userspace fails.
+ */
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+{
+        int len;
+        int ret;
+
+        if (!cnt)
+                return 0;
+
+        if (s->len <= s->readpos)
+                return -EBUSY;
+
+        len = s->len - s->readpos;
+        if (cnt > len)
+                cnt = len;
+        ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+        if (ret == cnt)
+                return -EFAULT;
+
+        cnt -= ret;
+
+        s->readpos += cnt;
+        return cnt;
+}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3ce3c4ccfc94..7d7a07e9b9e9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -939,19 +939,20 @@ out:
         return ret;
 }
 
+/* TODO add a seq_buf_to_buffer() */
 static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 {
         int len;
 
-        if (s->len <= s->readpos)
+        if (s->seq.len <= s->seq.readpos)
                 return -EBUSY;
 
-        len = s->len - s->readpos;
+        len = s->seq.len - s->seq.readpos;
         if (cnt > len)
                 cnt = len;
-        memcpy(buf, s->buffer + s->readpos, cnt);
+        memcpy(buf, s->buffer + s->seq.readpos, cnt);
 
-        s->readpos += cnt;
+        s->seq.readpos += cnt;
         return cnt;
 }
 
@@ -4315,6 +4316,8 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
                 goto out;
         }
 
+        trace_seq_init(&iter->seq);
+
         /*
          * We make a copy of the current tracer to avoid concurrent
          * changes on it while we are reading.
@@ -4511,18 +4514,18 @@ waitagain:
         trace_access_lock(iter->cpu_file);
         while (trace_find_next_entry_inc(iter) != NULL) {
                 enum print_line_t ret;
-                int len = iter->seq.len;
+                int len = iter->seq.seq.len;
 
                 ret = print_trace_line(iter);
                 if (ret == TRACE_TYPE_PARTIAL_LINE) {
                         /* don't print partial lines */
-                        iter->seq.len = len;
+                        iter->seq.seq.len = len;
                         break;
                 }
                 if (ret != TRACE_TYPE_NO_CONSUME)
                         trace_consume(iter);
 
-                if (iter->seq.len >= cnt)
+                if (iter->seq.seq.len >= cnt)
                         break;
 
                 /*
@@ -4538,7 +4541,7 @@ waitagain:
 
         /* Now copy what we have to the user */
         sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-        if (iter->seq.readpos >= iter->seq.len)
+        if (iter->seq.seq.readpos >= iter->seq.seq.len)
                 trace_seq_init(&iter->seq);
 
         /*
@@ -4576,16 +4579,16 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 
         /* Seq buffer is page-sized, exactly what we need. */
         for (;;) {
-                count = iter->seq.len;
+                count = iter->seq.seq.len;
                 ret = print_trace_line(iter);
-                count = iter->seq.len - count;
+                count = iter->seq.seq.len - count;
                 if (rem < count) {
                         rem = 0;
-                        iter->seq.len -= count;
+                        iter->seq.seq.len -= count;
                         break;
                 }
                 if (ret == TRACE_TYPE_PARTIAL_LINE) {
-                        iter->seq.len -= count;
+                        iter->seq.seq.len -= count;
                         break;
                 }
 
@@ -4666,13 +4669,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
                 /* Copy the data into the page, so we can start over. */
                 ret = trace_seq_to_buffer(&iter->seq,
                                           page_address(spd.pages[i]),
-                                          iter->seq.len);
+                                          iter->seq.seq.len);
                 if (ret < 0) {
                         __free_page(spd.pages[i]);
                         break;
                 }
                 spd.partial[i].offset = 0;
-                spd.partial[i].len = iter->seq.len;
+                spd.partial[i].len = iter->seq.seq.len;
 
                 trace_seq_init(&iter->seq);
         }
@@ -5673,7 +5676,7 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
         cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
         trace_seq_printf(s, "read events: %ld\n", cnt);
 
-        count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
+        count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);
 
         kfree(s);
 
@@ -6636,11 +6639,11 @@ void
 trace_printk_seq(struct trace_seq *s)
 {
         /* Probably should print a warning here. */
-        if (s->len >= TRACE_MAX_PRINT)
-                s->len = TRACE_MAX_PRINT;
+        if (s->seq.len >= TRACE_MAX_PRINT)
+                s->seq.len = TRACE_MAX_PRINT;
 
         /* should be zero ended, but we are paranoid. */
-        s->buffer[s->len] = 0;
+        s->buffer[s->seq.len] = 0;
 
         printk(KERN_TRACE "%s", s->buffer);
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index f9d0cbe014b7..4d0067dd7f88 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,7 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
         mutex_unlock(&event_mutex);
 
         if (file)
-                r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+                r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
 
         kfree(s);
 
@@ -1210,7 +1210,7 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
         trace_seq_init(s);
 
         print_subsystem_event_filter(system, s);
-        r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+        r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
 
         kfree(s);
 
@@ -1265,7 +1265,7 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
         trace_seq_init(s);
 
         func(s);
-        r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+        r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
 
         kfree(s);
 
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 100288d10e1f..6d1342ae7a44 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1154,9 +1154,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
         }
 
         /* Strip ending newline */
-        if (s->buffer[s->len - 1] == '\n') {
-                s->buffer[s->len - 1] = '\0';
-                s->len--;
+        if (s->buffer[s->seq.len - 1] == '\n') {
+                s->buffer[s->seq.len - 1] = '\0';
+                s->seq.len--;
         }
 
         trace_seq_puts(s, " */\n");
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index fabfa0f190a3..8c0c54fe674b 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -27,10 +27,19 @@
 #include <linux/trace_seq.h>
 
 /* How much buffer is left on the trace_seq? */
-#define TRACE_SEQ_BUF_LEFT(s) ((PAGE_SIZE - 1) - (s)->len)
+#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
 
 /* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
+
+/*
+ * trace_seq should work with being initialized with 0s.
+ */
+static inline void __trace_seq_init(struct trace_seq *s)
+{
+        if (unlikely(!s->seq.size))
+                trace_seq_init(s);
+}
 
 /**
  * trace_print_seq - move the contents of trace_seq into a seq_file
@@ -43,10 +52,11 @@
  */
 int trace_print_seq(struct seq_file *m, struct trace_seq *s)
 {
-        unsigned int len = TRACE_SEQ_BUF_USED(s);
         int ret;
 
-        ret = seq_write(m, s->buffer, len);
+        __trace_seq_init(s);
+
+        ret = seq_buf_print_seq(m, &s->seq);
 
         /*
          * Only reset this buffer if we successfully wrote to the
@@ -72,24 +82,23 @@ int trace_print_seq(struct seq_file *m, struct trace_seq *s)
  */
 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+        unsigned int save_len = s->seq.len;
         va_list ap;
-        int ret;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         va_start(ap, fmt);
-        ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+        seq_buf_vprintf(&s->seq, fmt, ap);
         va_end(ap);
 
         /* If we can't write it all, don't bother writing anything */
-        if (ret >= len) {
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
                 s->full = 1;
-                return;
         }
-
-        s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 
@@ -104,14 +113,19 @@ EXPORT_SYMBOL_GPL(trace_seq_printf);
 void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
                       int nmaskbits)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-        int ret;
+        unsigned int save_len = s->seq.len;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
-        ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
-        s->len += ret;
+        __trace_seq_init(s);
+
+        seq_buf_bitmask(&s->seq, maskp, nmaskbits);
+
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
+                s->full = 1;
+        }
 }
 EXPORT_SYMBOL_GPL(trace_seq_bitmask);
 
@@ -128,21 +142,20 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask);
  */
 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-        int ret;
+        unsigned int save_len = s->seq.len;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
-        ret = vsnprintf(s->buffer + s->len, len, fmt, args);
+        __trace_seq_init(s);
+
+        seq_buf_vprintf(&s->seq, fmt, args);
 
         /* If we can't write it all, don't bother writing anything */
-        if (ret >= len) {
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
                 s->full = 1;
-                return;
         }
-
-        s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_vprintf);
 
@@ -163,21 +176,21 @@ EXPORT_SYMBOL_GPL(trace_seq_vprintf);
  */
 void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
-        unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-        int ret;
+        unsigned int save_len = s->seq.len;
 
-        if (s->full || !len)
+        if (s->full)
                 return;
 
-        ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+        __trace_seq_init(s);
+
+        seq_buf_bprintf(&s->seq, fmt, binary);
 
         /* If we can't write it all, don't bother writing anything */
-        if (ret >= len) {
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
                 s->full = 1;
                 return;
         }
-
-        s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_bprintf);
 
@@ -198,13 +211,14 @@ void trace_seq_puts(struct trace_seq *s, const char *str)
         if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         if (len > TRACE_SEQ_BUF_LEFT(s)) {
                 s->full = 1;
                 return;
         }
 
-        memcpy(s->buffer + s->len, str, len);
-        s->len += len;
+        seq_buf_putmem(&s->seq, str, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_puts);
 
@@ -223,12 +237,14 @@ void trace_seq_putc(struct trace_seq *s, unsigned char c)
         if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         if (TRACE_SEQ_BUF_LEFT(s) < 1) {
                 s->full = 1;
                 return;
         }
 
-        s->buffer[s->len++] = c;
+        seq_buf_putc(&s->seq, c);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putc);
 
@@ -247,19 +263,17 @@ void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
         if (s->full)
                 return;
 
+        __trace_seq_init(s);
+
         if (len > TRACE_SEQ_BUF_LEFT(s)) {
                 s->full = 1;
                 return;
         }
 
-        memcpy(s->buffer + s->len, mem, len);
-        s->len += len;
+        seq_buf_putmem(&s->seq, mem, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem);
 
-#define MAX_MEMHEX_BYTES        8U
-#define HEX_CHARS               (MAX_MEMHEX_BYTES*2 + 1)
-
 /**
  * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
  * @s: trace sequence descriptor
@@ -273,32 +287,26 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem);
 void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
                          unsigned int len)
 {
-        unsigned char hex[HEX_CHARS];
-        const unsigned char *data = mem;
-        unsigned int start_len;
-        int i, j;
+        unsigned int save_len = s->seq.len;
 
         if (s->full)
                 return;
 
-        while (len) {
-                start_len = min(len, HEX_CHARS - 1);
-#ifdef __BIG_ENDIAN
-                for (i = 0, j = 0; i < start_len; i++) {
-#else
-                for (i = start_len-1, j = 0; i >= 0; i--) {
-#endif
-                        hex[j++] = hex_asc_hi(data[i]);
-                        hex[j++] = hex_asc_lo(data[i]);
-                }
-                if (WARN_ON_ONCE(j == 0 || j/2 > len))
-                        break;
-
-                /* j increments twice per loop */
-                len -= j / 2;
-                hex[j++] = ' ';
-
-                trace_seq_putmem(s, hex, j);
+        __trace_seq_init(s);
+
+        /* Each byte is represented by two chars */
+        if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {
+                s->full = 1;
+                return;
+        }
+
+        /* The added spaces can still cause an overflow */
+        seq_buf_putmem_hex(&s->seq, mem, len);
+
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
+                s->full = 1;
+                return;
         }
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
@@ -317,30 +325,28 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
  */
 int trace_seq_path(struct trace_seq *s, const struct path *path)
 {
-        unsigned char *p;
+        unsigned int save_len = s->seq.len;
+        int ret;
 
         if (s->full)
                 return 0;
 
+        __trace_seq_init(s);
+
         if (TRACE_SEQ_BUF_LEFT(s) < 1) {
                 s->full = 1;
                 return 0;
         }
 
-        p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
-        if (!IS_ERR(p)) {
-                p = mangle_path(s->buffer + s->len, p, "\n");
-                if (p) {
-                        s->len = p - s->buffer;
-                        return 1;
-                }
-        } else {
-                s->buffer[s->len++] = '?';
-                return 1;
+        ret = seq_buf_path(&s->seq, path);
+
+        if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+                s->seq.len = save_len;
+                s->full = 1;
+                return 0;
         }
 
-        s->full = 1;
-        return 0;
+        return ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_path);
 
@@ -366,25 +372,7 @@ EXPORT_SYMBOL_GPL(trace_seq_path);
  */
 int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
 {
-        int len;
-        int ret;
-
-        if (!cnt)
-                return 0;
-
-        if (s->len <= s->readpos)
-                return -EBUSY;
-
-        len = s->len - s->readpos;
-        if (cnt > len)
-                cnt = len;
-        ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
-        if (ret == cnt)
-                return -EFAULT;
-
-        cnt -= ret;
-
-        s->readpos += cnt;
-        return cnt;
+        __trace_seq_init(s);
+        return seq_buf_to_user(&s->seq, ubuf, cnt);
 }
 EXPORT_SYMBOL_GPL(trace_seq_to_user);