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Diffstat (limited to 'Documentation/hid/hid-bpf.rst')
| -rw-r--r-- | Documentation/hid/hid-bpf.rst | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/Documentation/hid/hid-bpf.rst b/Documentation/hid/hid-bpf.rst index a55f191d49a3..c205f92b7bcc 100644 --- a/Documentation/hid/hid-bpf.rst +++ b/Documentation/hid/hid-bpf.rst @@ -427,12 +427,22 @@ program first:: prog_fd = bpf_program__fd(hid_skel->progs.attach_prog); err = bpf_prog_test_run_opts(prog_fd, &tattrs); - return err; + if (err) + return err; + + return args.retval; /* the fd of the created bpf_link */ } Our userspace program can now listen to notifications on the ring buffer, and is awaken only when the value changes. +When the userspace program doesn't need to listen to events anymore, it can just +close the returned fd from :c:func:`attach_filter`, which will tell the kernel to +detach the program from the HID device. + +Of course, in other use cases, the userspace program can also pin the fd to the +BPF filesystem through a call to :c:func:`bpf_obj_pin`, as with any bpf_link. + Controlling the device ---------------------- |