The compilation only looks for linux/magic.h from the default include
paths, which does not include the source tree. This results in a build
error if linux/magic.h is not available or not installed.

For example, this build error occurs on CentOS 5.

$ make -C tools/lib/lk V=1
[...]
gcc -o debugfs.o -c -ggdb3 -Wall -Wextra -std=gnu99 -Werror -O6
-D_FORTIFY_SOURCE=2 -Wbad-function-cast -Wdeclaration-after-statement
-Wformat-security -Wformat-y2k -Winit-self -Wmissing-declarations
-Wmissing-prototypes -Wnested-externs -Wno-system-headers
-Wold-style-definition -Wpacked -Wredundant-decls -Wshadow
-Wstrict-aliasing=3 -Wstrict-prototypes -Wswitch-default -Wswitch-enum
-Wundef -Wwrite-strings -Wformat  -fPIC  -D_LARGEFILE64_SOURCE
-D_FILE_OFFSET_BITS=64 debugfs.c
debugfs.c:8:25: error: linux/magic.h: No such file or directory

The only symbol from linux/magic.h needed by debugfs.c is DEBUGFS_MAGIC,
and that is already defined in debugfs.h. linux/magic.h isn't providing
any extra symbols and can unincluded. This is similar to the approach by
perf, which has its own magic.h wrapper at
tools/perf/util/include/linux/magic.h
Signed-off-by: NVinson Lee <vlee@twitter.com>
Acked-by: NBorislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Vinson Lee <vlee@freedesktop.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1379546200-17028-1-git-send-email-vlee@freedesktop.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move them to util.c and simplify code a bit.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1361374353-30385-6-git-send-email-bp@alien8.deSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This introduces the tools/lib/lk library, that will gradually have the
routines that now are used in tools/perf/ and other tools and that can
be shared.

Start by carving out debugfs routines for general use.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1361374353-30385-5-git-send-email-bp@alien8.de
[ committer note: Add tools/lib/lk/ to perf's MANIFEST so that its tarballs continue to build ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

debugfs_premounted is written-to only so drop it. This functionality is
covered by debugfs_found now. Make it a bool while at it.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1361374353-30385-2-git-send-email-bp@alien8.deSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Following debugfs object functions are not referenced
within the code:

  int debugfs_valid_entry(const char *path);
  int debugfs_umount(void);
  int debugfs_write(const char *entry, const char *value);
  int debugfs_read(const char *entry, char *buffer, size_t size);
  void debugfs_force_cleanup(void);
  int debugfs_make_path(const char *element, char *buffer, int size);

Removing them.

Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1327674868-10486-3-git-send-email-jolsa@redhat.comSigned-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We don't need to have two PATH_MAX char sized arrays holding it, just
one in util/debugfs.c will do.

Also rename debugfs_path to tracing_events_path, as it is not the path
to debugfs, that is debugfs_mountpoint. Both are now accessible.

This will allow accessing this code in the perf python binding without
having to drag in perf.c and util/parse-events.c.

The defaults for these variables are the canonical "/sys/kernel/debug"
and "/sys/kernel/debug/tracing/events/", removing the need for simple
tools to call debugfs_mount(NULL).

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-ug9jvtjrsqbluuhqqxpvg30f@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

No need for multiple definitions for STR() and die(), also use SuSv2's
PATH_MAX instead of adding MAX_PATH.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-qpujjkw7u0bf0tr4wt55cr9y@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Remove redundant code for 'perf trace'
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <4B3870DE.7090500@cn.fujitsu.com>
[ v2: resolved conflicts with recent changes ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Mount debugfs filesystem under '/sys/kernel/debug', if it's not
mounted.
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <4B387090.7080407@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add routines to locate the debugfs mount point and to manage the
mounting and unmounting of the debugfs.
Signed-off-by: NClark Williams <williams@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091101155621.2b3503ee@torg>
Signed-off-by: NIngo Molnar <mingo@elte.hu>