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Samuel Wu
5ff4495544
Iterating through wakeup sources via sysfs or debugfs can be inefficient or restricted. Introduce BPF kfuncs to allow high-performance and safe in-kernel traversal of the wakeup_sources list. There is at least a 30x speedup for walking 150 wakeup sources and all their attributes. The new kfuncs include: - bpf_wakeup_sources_get_head() to obtain the list head. - bpf_wakeup_sources_read_lock/unlock() to manage the SRCU lock. For verifier safety, the underlying SRCU index is wrapped in an opaque 'struct bpf_ws_lock' pointer. This enables the use of KF_ACQUIRE and KF_RELEASE flags, allowing the BPF verifier to strictly enforce paired lock/unlock cycles and prevent resource leaks. Signed-off-by: Samuel Wu <wusamuel@google.com> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20260511174559.659782-2-wusamuel@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>