From patchwork Thu May 23 23:08:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kui-Feng Lee X-Patchwork-Id: 13672356 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-yw1-f173.google.com (mail-yw1-f173.google.com [209.85.128.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64E7084D25 for ; Thu, 23 May 2024 23:08:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716505739; cv=none; b=vD2pR2X3JJhFas6BZq8VBTqrkY31LcLWXBQiZO7avr2pfblOWH0bFyVd0wf4oNecaE4A4H2guCO6BnsZDbs2iLyVa9+RlPGw9PJtACBOE853iq+kkoZ0avLV9cFj3GqleM4Q3OBCE8bRanTIybnWaalpllVzDAOX+qrNl+PiBqU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716505739; c=relaxed/simple; bh=MWDCpjl9BLy3RGzWzjmcFwlOX12n4Lxxz8u31F8OV80=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=K81QuhB6EkNOShGH916v3Rj2sZg4hi7R4iJ+GwJjfaIhhSpz/PiA7x/RvuRdUbxayiF5KvcxwlarP6InOHqSigUBT7UVNRzvQ9QrUVHIx8mSVYJ2FUah/BsxStMeNAIF6BWQef0il/hE2sRlYnzFa6A3UI60wonJ29ms+Gf9s/k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=XWLR9T1s; arc=none smtp.client-ip=209.85.128.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="XWLR9T1s" Received: by mail-yw1-f173.google.com with SMTP id 00721157ae682-62a087bc74bso2609527b3.2 for ; Thu, 23 May 2024 16:08:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1716505736; x=1717110536; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=JsUJ/ZUPCANLU2SOSyqnWVxDYlfF/YXSX4GUUYnQdmY=; b=XWLR9T1skpg1XSsvc+4RLOQAPZ8ypWQpMB+Z8QPpQ2ixRQSovUu7OwdnaJPgYoVmlR OlsF4VRVvt2t3P8KPGAsb9XNQNJn9qDqX69ceCpQFvH3lz0ucNk+agHbXmvsu+6JRE3Z 7Kd9qtDp7+I8sbPaYAUD/uIRiuogWrT2s8BN8C84PBN4KPe2nEL9ZK5ZHYetFRjLrATr //00SXInLSKCFeqMWPF+t5gTaHKUBN9D7q2+uQVhSvr7jA7kybmM/RlP1UizM4Q3MOcB TSHc4TQ0UYQQX2v/FFhrMPPbu/7mfhm27+ZOFM5eaRBvQpMLyPSvktU7ZEAmGFg6E/aV ogeA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716505736; x=1717110536; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=JsUJ/ZUPCANLU2SOSyqnWVxDYlfF/YXSX4GUUYnQdmY=; b=YVNNL45tWXWwEYYmMLfD30FpsluPbD8gOKdAh1lEg6kAekALJEVz9WBbfGF+Ycy8Da YscQ/etZynEVTHOX3Opcf+4y04uIIJKbNtSquuBkWPr6PtI69VSNn9ZGycUtqyVKi+it Rb8/lM53eRTle2GIkStkWChIFkbQq0dCmIjNC3MHkUxmyQlGfOmndbrrLLcX8/HEA7tX /koSxKCq1v1HmjS1cKFSPyntpT+EV6w+gJbrcp3EO5vWvZubtoxD3r6e1RST33J0G4QR ru+8CorFgETNiyuiGhvFVcI4ZmXWOKVOEVraqkKHI5BDtE0I01B3ySB/YvXYgUXBaUJv sRBQ== X-Gm-Message-State: AOJu0YyZnKQ1ArHBpjL6iZrXkb9WiZESQ41r9aFJhg/KIgPK5bfD/M9m P39qyBKC+jvksOub/cBcPgTgQLZxsSqjttiCZZjcWQ5hA5xemsVK9Y9v3Q== X-Google-Smtp-Source: AGHT+IExVd9a5w5wA9Hgfxvdgo+IqYXLuBrgfOlhSG2QrOJUcWYRl16Iy/U3Q4bKHVqQOpm6g72g9g== X-Received: by 2002:a0d:d454:0:b0:61d:fd33:d065 with SMTP id 00721157ae682-62a08d8abe8mr6501767b3.15.1716505735842; Thu, 23 May 2024 16:08:55 -0700 (PDT) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:b7f1:1457:70d4:ab6c]) by smtp.gmail.com with ESMTPSA id 00721157ae682-62a0a37d5d0sm474087b3.16.2024.05.23.16.08.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 May 2024 16:08:55 -0700 (PDT) From: Kui-Feng Lee To: bpf@vger.kernel.org, ast@kernel.org, martin.lau@linux.dev, song@kernel.org, kernel-team@meta.com, andrii@kernel.org Cc: sinquersw@gmail.com, kuifeng@meta.com, Kui-Feng Lee Subject: [PATCH bpf-next v5 3/8] bpf: support epoll from bpf struct_ops links. Date: Thu, 23 May 2024 16:08:43 -0700 Message-Id: <20240523230848.2022072-4-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240523230848.2022072-1-thinker.li@gmail.com> References: <20240523230848.2022072-1-thinker.li@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Add epoll support to bpf struct_ops links to trigger EPOLLHUP event upon detachment. This patch implements the "poll" of the "struct file_operations" for BPF links and introduces a new "poll" operator in the "struct bpf_link_ops". By implementing "poll" of "struct bpf_link_ops" for the links of struct_ops, the file descriptor of a struct_ops link can be added to an epoll file descriptor to receive EPOLLHUP events. Signed-off-by: Kui-Feng Lee --- include/linux/bpf.h | 1 + kernel/bpf/bpf_struct_ops.c | 17 +++++++++++++++++ kernel/bpf/syscall.c | 31 ++++++++++++++++++++++++++----- 3 files changed, 44 insertions(+), 5 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index b600767ebe02..5f7496ef8b7c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1612,6 +1612,7 @@ struct bpf_link_ops { struct bpf_link_info *info); int (*update_map)(struct bpf_link *link, struct bpf_map *new_map, struct bpf_map *old_map); + __poll_t (*poll)(struct file *file, struct poll_table_struct *pts); }; struct bpf_tramp_link { diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index f2439acd9757..855a1b2b6e79 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -12,6 +12,7 @@ #include #include #include +#include struct bpf_struct_ops_value { struct bpf_struct_ops_common_value common; @@ -56,6 +57,7 @@ struct bpf_struct_ops_map { struct bpf_struct_ops_link { struct bpf_link link; struct bpf_map __rcu *map; + wait_queue_head_t wait_hup; }; static DEFINE_MUTEX(update_mutex); @@ -1167,15 +1169,28 @@ static int bpf_struct_ops_map_link_detach(struct bpf_link *link) mutex_unlock(&update_mutex); + wake_up_interruptible_poll(&st_link->wait_hup, EPOLLHUP); + return 0; } +static __poll_t bpf_struct_ops_map_link_poll(struct file *file, + struct poll_table_struct *pts) +{ + struct bpf_struct_ops_link *st_link = file->private_data; + + poll_wait(file, &st_link->wait_hup, pts); + + return rcu_access_pointer(st_link->map) ? 0 : EPOLLHUP; +} + static const struct bpf_link_ops bpf_struct_ops_map_lops = { .dealloc = bpf_struct_ops_map_link_dealloc, .detach = bpf_struct_ops_map_link_detach, .show_fdinfo = bpf_struct_ops_map_link_show_fdinfo, .fill_link_info = bpf_struct_ops_map_link_fill_link_info, .update_map = bpf_struct_ops_map_link_update, + .poll = bpf_struct_ops_map_link_poll, }; int bpf_struct_ops_link_create(union bpf_attr *attr) @@ -1213,6 +1228,8 @@ int bpf_struct_ops_link_create(union bpf_attr *attr) */ RCU_INIT_POINTER(link->map, map); + init_waitqueue_head(&link->wait_hup); + mutex_lock(&update_mutex); err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data, &link->link); if (err) { diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 13ad74ecf2cd..741f91153fe6 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3150,6 +3150,13 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp) } #endif +static __poll_t bpf_link_poll(struct file *file, struct poll_table_struct *pts) +{ + struct bpf_link *link = file->private_data; + + return link->ops->poll(file, pts); +} + static const struct file_operations bpf_link_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = bpf_link_show_fdinfo, @@ -3159,6 +3166,16 @@ static const struct file_operations bpf_link_fops = { .write = bpf_dummy_write, }; +static const struct file_operations bpf_link_fops_poll = { +#ifdef CONFIG_PROC_FS + .show_fdinfo = bpf_link_show_fdinfo, +#endif + .release = bpf_link_release, + .read = bpf_dummy_read, + .write = bpf_dummy_write, + .poll = bpf_link_poll, +}; + static int bpf_link_alloc_id(struct bpf_link *link) { int id; @@ -3201,7 +3218,9 @@ int bpf_link_prime(struct bpf_link *link, struct bpf_link_primer *primer) return id; } - file = anon_inode_getfile("bpf_link", &bpf_link_fops, link, O_CLOEXEC); + file = anon_inode_getfile("bpf_link", + link->ops->poll ? &bpf_link_fops_poll : &bpf_link_fops, + link, O_CLOEXEC); if (IS_ERR(file)) { bpf_link_free_id(id); put_unused_fd(fd); @@ -3229,7 +3248,9 @@ int bpf_link_settle(struct bpf_link_primer *primer) int bpf_link_new_fd(struct bpf_link *link) { - return anon_inode_getfd("bpf-link", &bpf_link_fops, link, O_CLOEXEC); + return anon_inode_getfd("bpf-link", + link->ops->poll ? &bpf_link_fops_poll : &bpf_link_fops, + link, O_CLOEXEC); } struct bpf_link *bpf_link_get_from_fd(u32 ufd) @@ -3239,7 +3260,7 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd) if (!f.file) return ERR_PTR(-EBADF); - if (f.file->f_op != &bpf_link_fops) { + if (f.file->f_op != &bpf_link_fops && f.file->f_op != &bpf_link_fops_poll) { fdput(f); return ERR_PTR(-EINVAL); } @@ -4966,7 +4987,7 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr, uattr); else if (f.file->f_op == &btf_fops) err = bpf_btf_get_info_by_fd(f.file, f.file->private_data, attr, uattr); - else if (f.file->f_op == &bpf_link_fops) + else if (f.file->f_op == &bpf_link_fops || f.file->f_op == &bpf_link_fops_poll) err = bpf_link_get_info_by_fd(f.file, f.file->private_data, attr, uattr); else @@ -5101,7 +5122,7 @@ static int bpf_task_fd_query(const union bpf_attr *attr, if (!file) return -EBADF; - if (file->f_op == &bpf_link_fops) { + if (file->f_op == &bpf_link_fops || file->f_op == &bpf_link_fops_poll) { struct bpf_link *link = file->private_data; if (link->ops == &bpf_raw_tp_link_lops) {