Pull tracing updates from Steven Rostedt:
- Remove eventfs_file descriptor
This is the biggest change, and the second part of making eventfs
create its files dynamically.
In 6.6 the first part was added, and that maintained a one to one
mapping between eventfs meta descriptors and the directories and file
inodes and dentries that were dynamically created. The directories
were represented by a eventfs_inode and the files were represented by
a eventfs_file.
In v6.7 the eventfs_file is removed. As all events have the same
directory make up (sched_switch has an "enable", "id", "format", etc
files), the handing of what files are underneath each leaf eventfs
directory is moved back to the tracing subsystem via a callback.
When an event is added to the eventfs, it registers an array of
evenfs_entry's. These hold the names of the files and the callbacks
to call when the file is referenced. The callback gets the name so
that the same callback may be used by multiple files. The callback
then supplies the filesystem_operations structure needed to create
this file.
This has brought the memory footprint of creating multiple eventfs
instances down by 2 megs each!
- User events now has persistent events that are not associated to a
single processes. These are privileged events that hang around even
if no process is attached to them
- Clean up of seq_buf
There's talk about using seq_buf more to replace strscpy() and
friends. But this also requires some minor modifications of seq_buf
to be able to do this
- Expand instance ring buffers individually
Currently if boot up creates an instance, and a trace event is
enabled on that instance, the ring buffer for that instance and the
top level ring buffer are expanded (1.4 MB per CPU). This wastes
memory as this happens when nothing is using the top level instance
- Other minor clean ups and fixes
* tag 'trace-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (34 commits)
seq_buf: Export seq_buf_puts()
seq_buf: Export seq_buf_putc()
eventfs: Use simple_recursive_removal() to clean up dentries
eventfs: Remove special processing of dput() of events directory
eventfs: Delete eventfs_inode when the last dentry is freed
eventfs: Hold eventfs_mutex when calling callback functions
eventfs: Save ownership and mode
eventfs: Test for ei->is_freed when accessing ei->dentry
eventfs: Have a free_ei() that just frees the eventfs_inode
eventfs: Remove "is_freed" union with rcu head
eventfs: Fix kerneldoc of eventfs_remove_rec()
tracing: Have the user copy of synthetic event address use correct context
eventfs: Remove extra dget() in eventfs_create_events_dir()
tracing: Have trace_event_file have ref counters
seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str()
eventfs: Fix typo in eventfs_inode union comment
eventfs: Fix WARN_ON() in create_file_dentry()
powerpc: Remove initialisation of readpos
tracing/histograms: Simplify last_cmd_set()
seq_buf: fix a misleading comment
...
There are scenes that we want to show the character value of traced
arguments other than a decimal or hexadecimal or string value for debug
convinience. I add a new type named 'char' to do it and a new test case
file named 'kprobe_args_char.tc' to do selftest for char type.
For example:
The to be traced function is 'void demo_func(char type, char *name);', we
can add a kprobe event as follows to show argument values as we want:
echo 'p:myprobe demo_func $arg1:char +0($arg2):char[5]' > kprobe_events
we will get the following trace log:
... myprobe: (demo_func+0x0/0x29) arg1='A' arg2={'b','p','f','1',''}
Link: https://lore.kernel.org/all/20221219110613.367098-1-dolinux.peng@gmail.com/
Signed-off-by: Donglin Peng <dolinux.peng@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
