From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta0.migadu.com (out-183.mta0.migadu.com [91.218.175.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 52EEA33DECB for ; Fri, 9 Jan 2026 21:39:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767994794; cv=none; b=kK2p2DU1dgBp4Qxkjp7B+dLIo9b3R5gEHsRWa/XIHl10DwEfYBVzwVR+ZPUw1IEUzQ/WpvexESnEZyK4Vg3I3EhyA/TH8DZq2i9/tRdJjKsY4Gxjn2XoH5u459dlhKCQ8i+GZK5FzWzvtkdFsRcWvn5q8xNm43filedvw+GV3Oo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767994794; c=relaxed/simple; bh=2TONpOtiAdOpe+8CZmPigeyTFItzuphg78IHpEPQQHs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ZE0aj4WQU8semnjXAvsEHbTaIE/U2N/IMlekG7a9KGsEo6djkFzR1O2gEZkpOEIA0bHu/gScW+0xrYv/6Xqj6fXYumyIaCKjrKEGH5DQ4HIrOh5TqQsDGILos7lCDP/0OeejuTWxynb356Bjk1roOUjkKE8gT1Ca3XnA2B4GO0k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=SYXUhEP6; arc=none smtp.client-ip=91.218.175.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="SYXUhEP6" Message-ID: <0c4d84ab-1725-45bc-9c1c-8bdc1f5fc032@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1767994787; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=c8tMXOnuAtuUkCGUZeluaJcBlvfdJrx3OeoezqVhGzw=; b=SYXUhEP6bgYIYohlnrcLcTeFyL0VUkmM0y7cNjZ++hgvEHwXrEkf0CSCd9HSpCWa6edufR HsQbysZJ5Wjg8UKxZmpxuBnY3j7x1QWctU2oBEIrLSCNaPoKkQXrQKaXZb7kMZcLQGbjLc RmMAWKT9Jxcw+4/aIfQCJ4oaUmHaOvk= Date: Fri, 9 Jan 2026 13:39:40 -0800 Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v1 08/10] bpf: Add bpf_task_work_schedule_* kfuncs with KF_IMPLICIT_ARGS To: Alexei Starovoitov Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Eduard Zingerman , Mykyta Yatsenko , Tejun Heo , Alan Maguire , Benjamin Tissoires , Jiri Kosina , bpf , LKML , "open list:HID CORE LAYER" , sched-ext@lists.linux.dev References: <20260109184852.1089786-1-ihor.solodrai@linux.dev> <20260109184852.1089786-9-ihor.solodrai@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Ihor Solodrai In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 1/9/26 12:47 PM, Alexei Starovoitov wrote: > On Fri, Jan 9, 2026 at 12:02 PM Ihor Solodrai wrote: >> >> On 1/9/26 11:58 AM, Alexei Starovoitov wrote: >>> On Fri, Jan 9, 2026 at 10:50 AM Ihor Solodrai wrote: >>>> >>>> +__bpf_kfunc int bpf_task_work_schedule_signal(struct task_struct *task, struct bpf_task_work *tw, >>>> + void *map__map, bpf_task_work_callback_t callback, >>>> + struct bpf_prog_aux *aux) >>>> +{ >>>> + return bpf_task_work_schedule(task, tw, map__map, callback, aux, TWA_SIGNAL); >>>> +} >>>> + >>>> __bpf_kfunc int bpf_task_work_schedule_signal_impl(struct task_struct *task, >>>> struct bpf_task_work *tw, void *map__map, >>>> bpf_task_work_callback_t callback, >>>> void *aux__prog) >>>> { >>>> - return bpf_task_work_schedule(task, tw, map__map, callback, aux__prog, TWA_SIGNAL); >>>> + return bpf_task_work_schedule_signal(task, tw, map__map, callback, aux__prog); >>>> } >>> >>> I thought we decided that _impl() will not be marked as __bpf_kfunc >>> and will not be in BTF_ID(func, _impl). >>> We can mark it as __weak noinline and it will be in kallsyms. >>> That's all we need for the verifier and resolve_btfid, no? >>> >>> Sorry, it's been a long time. I must have forgotten something. >> >> For the *generated* _impl kfuncs there is no decl tags and the ids are >> absent from BTF_ID sets, yes. >> >> However for the "legacy" cases it must be there for backwards >> compatibility, as well as relevant verifier checks. > > I see. > I feel bpf_task_work_schedule_resume() is ok to break, since it's so new. > We can remove bpf_task_work_schedule_[resume|singal]_impl() > to avoid carrying forward forever. > > bpf_stream_vprintk_impl() is not that clear. I would remove it too. That leaves only bpf_wq_set_callback_impl(). Can we break that too? Then there won't be legacy cases at all. It was introduced in v6.16 along the with __prog suffix [1][2]. If we go this route, we could clean up __prog support/docs too. I think it's worth it to make an "all or nothing" decision here: either break all 4 existing kfuncs, or backwards-support all of them. git tag --contains bc049387b41f | grep -v rc v6.16 v6.17 v6.18 [1] https://lore.kernel.org/all/20250513142812.1021591-1-memxor@gmail.com/ [2] https://lore.kernel.org/all/20240420-bpf_wq-v2-13-6c986a5a741f@kernel.org/