There has been complaints that tracing is tied too much to debugfs,
as there are systems that would like to perform tracing, but do
not mount debugfs for security reasons. That is because any subsystem
may use debugfs for debugging, and these interfaces are not always
tested for security.
Creating a new tracefs that the tracing directory will now be attached
to allows system admins the ability to access the tracing directory
without the need to mount debugfs.
Another advantage is that debugfs does not support the system calls
for mkdir and rmdir. Tracing uses these system calls to create new
instances for sub buffers. This was done by a hack that hijacked the
dentry ops from the "instances" debugfs dentry, and replacing it with
one that could work.
Instead of using this hack, tracefs can provide a proper interface to
allow the tracing system to have a mkdir and rmdir feature.
To maintain backward compatibility with older tools that expect that
the tracing directory is mounted with debugfs, the tracing directory
is still created under debugfs and tracefs is automatically mounted
there.
Finally, a new directory is created when tracefs is enabled called
/sys/kernel/tracing. This will be the new location that system admins
may mount tracefs if they are not using debugfs.
Steven Rostedt (Red Hat) (5):
tracefs: Add new tracefs file system
tracing: Convert the tracing facility over to use tracefs
tracing: Automatically mount tracefs on debugfs/tracing
tracing: Have mkdir and rmdir be part of tracefs
tracefs: Add directory /sys/kernel/tracing
----
fs/Makefile | 1 +
fs/tracefs/Makefile | 4 +
fs/tracefs/inode.c | 649 +++++++++++++++++++++++++++++++++++
include/uapi/linux/magic.h | 2 +
kernel/trace/ftrace.c | 22 +-
kernel/trace/trace.c | 178 +++++-----
kernel/trace/trace.h | 2 +-
kernel/trace/trace_events.c | 32 +-
kernel/trace/trace_functions_graph.c | 7 +-
kernel/trace/trace_kprobe.c | 10 +-
kernel/trace/trace_probe.h | 2 +-
kernel/trace/trace_stat.c | 10 +-
scripts/tags.sh | 2 +-
13 files changed, 789 insertions(+), 132 deletions(-)
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