Hi, Here is the v9 of the series to improve backup instances of the persistent ring buffer. The previous version is here:
https://lore.kernel.org/all/177071300558.2293046.12057922262682243630.st...@mhiramat.tok.corp.google.com/ In this version, I removed bugfixes (those are actual fixes/minor updates) and the force permission check in tracefs because superuser can modify the permission by itself. Instead, simply add read-only and FMODE_WRITE check in the related open() file operations[1/3]. Also, I fixed 2 bugs in autoremove patch to init dedicated workqueue correctly [2/3]. Series Description ------------------ Since backup instances are a kind of snapshot of the persistent ring buffer, it should be readonly. And if it is readonly there is no reason to keep it after reading all data via trace_pipe because the data has been consumed. But user should be able to remove the readonly instance by rmdir or truncating `trace` file. Thus, [1/3] makes backup instances readonly (not able to write any events, cleanup trace, change buffer size). Also, [2/3] removes the backup instance after consuming all data via trace_pipe. With this improvements, even if we makes a backup instance (using the same amount of memory of the persistent ring buffer), it will be removed after reading the data automatically. Thanks, --- Masami Hiramatsu (Google) (3): tracing: Make the backup instance non-reusable tracing: Remove the backup instance automatically after read tracing/Documentation: Add a section about backup instance Documentation/trace/debugging.rst | 19 ++++ kernel/trace/trace.c | 166 +++++++++++++++++++++++++++++-------- kernel/trace/trace.h | 13 +++ kernel/trace/trace_boot.c | 5 + kernel/trace/trace_events.c | 76 ++++++++++------- 5 files changed, 208 insertions(+), 71 deletions(-) -- Masami Hiramatsu (Google) <[email protected]>
