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tracing: Fix probes written to the set_ftrace_filter file

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Now that there's a library that accesses the tracefs file system,
 (libtracefs), the way the files are interacted with is slightly
 different than the command line. For instance, the write() system
 call is used directly instead of an echo. This exposes some old bugs.
 
 If a probe is written to "set_ftrace_filter" without any white space
 after it, it will be ignored. This is because the write expects
 that a string written to it that does not end with white spaces thinks
 there is more to come. But if the file is closed, the release function
 needs to finish it. The "set_ftrace_filter" release function handles
 the filter part of the "set_ftrace_filter" file, but did not handle
 the probe part.
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Merge tag 'trace-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix from Steven Rostedt:
 "Fix probes written to the set_ftrace_filter file

  Now that there's a library that accesses the tracefs file system
  (libtracefs), the way the files are interacted with is slightly
  different than the command line. For instance, the write() system call
  is used directly instead of an echo. This exposes some old bugs.

  If a probe is written to "set_ftrace_filter" without any white space
  after it, it will be ignored. This is because the write expects that a
  string written to it that does not end with white spaces thinks there
  is more to come. But if the file is closed, the release function needs
  to finish it. The "set_ftrace_filter" release function handles the
  filter part of the "set_ftrace_filter" file, but did not handle the
  probe part"

* tag 'trace-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Handle commands when closing set_ftrace_filter file
This commit is contained in:
Linus Torvalds 2021-05-06 10:03:38 -07:00
commit 7ec901b6fa
1 changed files with 4 additions and 1 deletions
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5
kernel/trace/ftrace.c
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@ -5624,7 +5624,10 @@ int ftrace_regex_release(struct inode *inode, struct file *file)
parser = &iter->parser;
if (trace_parser_loaded(parser)) {
ftrace_match_records(iter->hash, parser->buffer, parser->idx);
int enable = !(iter->flags & FTRACE_ITER_NOTRACE);
ftrace_process_regex(iter, parser->buffer,
parser->idx, enable);
}
trace_parser_put(parser);