On Tue, May 30, 2023 at 04:52:59PM -0700, Beau Belgrave wrote: > As part of the discussions for user_events aligning to be used with eBPF > it became clear [1] we needed a way to delete events without having to rely > upon the delete IOCTL. Steven suggested that we simply have an owner This patch set is not addressing the issues I pointed out earlier. It adds a new flag and new api. It's not a fix. > for the event, however, the event can be held by more than just the > first register FD, such as perf/ftrace or additional registers. In order > to handle all those cases, we must only delete after all references are > gone from both user and kernel space. > > This series adds a new register flag, USER_EVENT_REG_AUTO_DEL, which > causes the event to delete itself upon the last put reference. We cannot Do not introduce a new flag. Make this default. > fully drop the delete IOCTL, since we still want to enable events to be > registered early via dynamic_events and persist. If the auto delete flag > was used during dynamic_events, the event would delete immediately. You have to delete this broken "delete via ioctl" api. For persistent events you need a different api in its own name scope, so it doesn't conflict with per-fd events. > We have a few key events that we enable immediately after boot and are > monitored in our environments. Today this is done via dynamic events, > however, it could also be done directly via the ABI by not passing the > auto delete flag. > > NOTE: I'll need to merge this work once we take these [2] [3] patches > into for-next. I'm happy to do so once they land there. > > 1: https://lore.kernel.org/linux-trace-kernel/20230518093600.3f119d68@xxxxxxxxxxxxxxxxxxxx/ > 2: https://lore.kernel.org/linux-trace-kernel/20230529032100.286534-1-sunliming@xxxxxxxxxx/ > 3: https://lore.kernel.org/linux-trace-kernel/20230519230741.669-1-beaub@xxxxxxxxxxxxxxxxxxx/ > > Beau Belgrave (5): > tracing/user_events: Store register flags on events > tracing/user_events: Track refcount consistently via put/get > tracing/user_events: Add flag to auto-delete events > tracing/user_events: Add self-test for auto-del flag > tracing/user_events: Add auto-del flag documentation > > Documentation/trace/user_events.rst | 21 +- > include/uapi/linux/user_events.h | 10 +- > kernel/trace/trace_events_user.c | 183 ++++++++++++++---- > .../testing/selftests/user_events/abi_test.c | 115 ++++++++++- > 4 files changed, 278 insertions(+), 51 deletions(-) > > > base-commit: 3862f86c1529fa0016de6344eb974877b4cd3838 > -- > 2.25.1 >
