The seq_buf functions are rather useful outside of tracing. Instead
of having it be dependent on CONFIG_TRACING, move the code into lib/
and allow other users to have access to it even when tracing is not
configured.

The seq_buf utility is similar to the seq_file utility, but instead of
writing sending data back up to userland, it writes it into a buffer
defined at seq_buf_init(). This allows us to send a descriptor around
that writes printf() formatted strings into it that can be retrieved
later.

It is currently used by the tracing facility for such things like trace
events to convert its binary saved data in the ring buffer into an
ASCII human readable context to be displayed in /sys/kernel/debug/trace.

It can also be used for doing NMI prints safely from NMI context into
the seq_buf and retrieved later and dumped to printk() safely. Doing
printk() from an NMI context is dangerous because an NMI can preempt
a current printk() and deadlock on it.

Link: http://lkml.kernel.org/p/20140619213952.058255809@goodmis.orgTested-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Reviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The function bstr_printf() from lib/vsprnintf.c is only available if
CONFIG_BINARY_PRINTF is defined. This is due to the only user currently
being the tracing infrastructure, which needs to select this config
when tracing is configured. Until there is another user of the binary
printf formats, this will continue to be the case.

Since seq_buf.c is now lives in lib/ and is compiled even without
tracing, it must encompass its use of bstr_printf() which is used
by seq_buf_printf(). This too is only used by the tracing infrastructure
and is still encapsulated by the CONFIG_BINARY_PRINTF.

Link: http://lkml.kernel.org/r/20141104160222.969013383@goodmis.orgTested-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Reviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Add two helper functions; seq_buf_get_buf() and seq_buf_commit() that
are used by seq_buf_path(). This makes the code similar to the
seq_file: seq_path() function, and will help to be able to consolidate
the functions between seq_file and trace_seq.

Link: http://lkml.kernel.org/r/20141104160222.644881406@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.977571447@goodmis.orgTested-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Reviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently seq_buf is full when all but one byte of the buffer is
filled. Change it so that the seq_buf is full when all of the
buffer is filled.

Some of the functions would fill the buffer completely and report
everything was fine. This was inconsistent with the max of size - 1.
Changing this to be max of size makes all functions consistent.

Link: http://lkml.kernel.org/r/20141104160222.502133196@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.811957882@goodmis.orgTested-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Reviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Add a seq_buf_can_fit() helper function that removes the possible mistakes
of comparing the seq_buf length plus added data compared to the size of
the buffer.

Link: http://lkml.kernel.org/r/20141118164025.GL23958@pathway.suse.czReviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

As the seq_buf->len will soon be +1 size when there's an overflow, we
must use trace_seq_used() or seq_buf_used() methods to get the real
length. This will prevent buffer overflow issues if just the len
of the seq_buf descriptor is used to copy memory.

Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.homeReported-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
private macro to let callers have a method to know how much of the
seq_buf was written to.

Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
Link: http://lkml.kernel.org/r/20141114011413.321654244@goodmis.orgReviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Rewrite seq_buf_path() like it is done in seq_path() and allow
it to accept any escape character instead of just "\n".

Making seq_buf_path() like seq_path() will help prevent problems
when converting seq_file to use the seq_buf logic.

Link: http://lkml.kernel.org/r/20141104160222.048795666@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.338523371@goodmis.orgTested-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Reviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

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.orgTested-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Reviewed-by: NPetr Mladek <pmladek@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>