|
The purpose is to simplify the use of bpf_wq to defer blocking
operations in a sleepable context. Compared to a more "classic"
async approach, there is no sync mechanism to wait for the async
to finish.
The "simple" API is the following:
```
static int HID_BPF_ASYNC(async_fun)(struct hid_bpf_ctx *hctx)
{
bpf_printk("%s", __fun__);
return 0;
}
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
ctx->retval = HID_BPF_ASYNC_INIT(async_fun);
return 0;
}
SEC(HID_BPF_DEVICE_EVENT)
int BPF_PROG(event_handler, struct hid_bpf_ctx *hctx)
{
/* async_fun() can be called now, it's not a sleepable
* function in this example
*/
async_fun(hctx);
/* but we can also delay the call by 10 ms */
HID_BPF_ASYNC_DELAYED_CALL(async_fun, hctx, 10);
return 0;
}
HID_BPF_OPS(xppen_ack05_remote) = {
.hid_device_event = (void *)event_handler,
};
```
Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/133
Acked-by: Jiri Kosina <jkosina@suse.com>
Link: https://patch.msgid.link/20250207-bpf-import-2025-02-07-v1-6-6048fdd5a206@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
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