From patchwork Tue Feb 6 12:51:45 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Pirko X-Patchwork-Id: 13547221 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-lf1-f43.google.com (mail-lf1-f43.google.com [209.85.167.43]) (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 8F81812E1FB for ; Tue, 6 Feb 2024 12:51:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.43 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707223914; cv=none; b=KlHB942j6Ua1x2r+B7CyGswkuVAzdHiJArcyoor5Rh/ez0N0XTZjvmddtImvqdgGB5jTqVvepgHvvWm5q7bMBYzE+F22NydFMXGeTDFegWYqiHNxP6K7Ki0+3SyHrprjcaMhh/EZiYua6GA+Se09KPUPTKJ9Frzqgcq1fLjgCB0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707223914; c=relaxed/simple; bh=+zBtpt/Ad+Exm2q8njKeFrta0cT06Gw2DnOsPFb33IM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=nxnXXgXJeO0Sd9CFy7IKg4B5UbKtZBSR4Z6uN6Ec0d0uOkhjka9quuZi54rWdfrWbbjAf/N6PCIk0i182BQBivFVdHxlMkQcXJ9JYE0hmmmB5dAbW7RIJhxeyfSTLviitNUJt0EKxrSIRFnvA+jhuTobPdmqe35KCnTRBnCwiW8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=resnulli.us; spf=none smtp.mailfrom=resnulli.us; dkim=pass (2048-bit key) header.d=resnulli-us.20230601.gappssmtp.com header.i=@resnulli-us.20230601.gappssmtp.com header.b=sa0rskME; arc=none smtp.client-ip=209.85.167.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=resnulli.us Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=resnulli.us Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=resnulli-us.20230601.gappssmtp.com header.i=@resnulli-us.20230601.gappssmtp.com header.b="sa0rskME" Received: by mail-lf1-f43.google.com with SMTP id 2adb3069b0e04-51025cafb51so8251708e87.2 for ; Tue, 06 Feb 2024 04:51:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=resnulli-us.20230601.gappssmtp.com; s=20230601; t=1707223909; x=1707828709; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=1KKARUp87LF6c9UcQtyI6AFhE1UpTF4lkCFhJwlnTdM=; b=sa0rskMEUffsIa+kWpFee2nRzhO+lXwYkQwys6JEm7KkfsoP9QO11QDnkp9UjEGCWw jY7wUtwk6riFgfP0E3fx5d3ZRtDzcMg1jEfi5VSw79/16NIMfsm4nT7HZVhicbyvJUAu ey74maR0S49tmDkKPSzzIpMaLW3FEoCGwobSzHo7tet5U5gg2KaWV0QMcAi3Mu0PiPqo UKTrJwM0arMUa2gjIZnd7NfgaKjVKMgeqzyIjUwGmWLXZSNlgu6WkYoERmj6sO5RexOw 5fo/NXinXYgYUy/TpK1QhjhvG7/ziD39M4NiPcuqQ2iYW758HRqw9PRj5M6ot8nBmThq IgfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707223909; x=1707828709; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=1KKARUp87LF6c9UcQtyI6AFhE1UpTF4lkCFhJwlnTdM=; b=Q7BjGfJCnuHZF8Zu+3Bj6nTe6gTyC8u6AKjh3ymirxD3LUcki2xPC7jIz2HwqXSRWU kqYVWCcaZczBi7bOtBUcZ0TCqU/UrLlQo/GnL6SAf0XMfhxKBPVikgYHiEHkeFFOZt0F JCglwyRDH/rr4Pf5JICqfOmmwN4BillVxF4orCDIba7TKR3/J0qr6g59iTq7WPXCRCF6 9p/HALh0dxVDOtD+QIfMKSqpIGXtsQ2uU3gHxCmP8MtOKbnKNgDcJQ/2JsK8q9czft/F SlBgeHNiWB8H5zGlfnLqSD9rsybW6FVEKD9VYHjG+PsAoEPXvM8bZKLVs4uWMZAoMvt6 ZSog== X-Gm-Message-State: AOJu0YwtSjx2UDQqstj5CD13av8zwMkQvLrbMyGI3iXoHL/fyXgtlr/G nutH1VfrK4cNt1r1ddAlr0kI7N5VRTYTRkq8Ej8T+POdfKgOKGDqvAYsM4Qfq7AGM0wTJIzkXha ov20= X-Google-Smtp-Source: AGHT+IHMPJPr/8nwBUrHQTa0uygSuf0u603eVCCKcaJHxkqjihIwX253Q5QfrRE0X/J5oIc3X5FImA== X-Received: by 2002:a19:760c:0:b0:511:621a:5d5f with SMTP id c12-20020a19760c000000b00511621a5d5fmr82899lff.39.1707223909250; Tue, 06 Feb 2024 04:51:49 -0800 (PST) X-Forwarded-Encrypted: i=0; AJvYcCWc1BQ/1UG4tDjCcd4fZfW2GkJsFdfxwWR3uDqLqtzZf67w0T2mTVjO1Om3ygPbr0YvqBTpAAtoxjpyQ6PHsb47iJpf/zdcdmv3cdYLkUO074TYEk3f3uAVtzQZaTIrApw= Received: from localhost ([193.47.165.251]) by smtp.gmail.com with ESMTPSA id cb6-20020a170906a44600b00a35a11fd795sm1102910ejb.129.2024.02.06.04.51.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Feb 2024 04:51:48 -0800 (PST) From: Jiri Pirko To: netdev@vger.kernel.org Cc: vadim.fedorenko@linux.dev, arkadiusz.kubalewski@intel.com Subject: [patch net] dpll: fix possible deadlock during netlink dump operation Date: Tue, 6 Feb 2024 13:51:45 +0100 Message-ID: <20240206125145.354557-1-jiri@resnulli.us> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Jiri Pirko Recently, I've been hitting following deadlock warning during dpll pin dump: [52804.637962] ====================================================== [52804.638536] WARNING: possible circular locking dependency detected [52804.639111] 6.8.0-rc2jiri+ #1 Not tainted [52804.639529] ------------------------------------------------------ [52804.640104] python3/2984 is trying to acquire lock: [52804.640581] ffff88810e642678 (nlk_cb_mutex-GENERIC){+.+.}-{3:3}, at: netlink_dump+0xb3/0x780 [52804.641417] but task is already holding lock: [52804.642010] ffffffff83bde4c8 (dpll_lock){+.+.}-{3:3}, at: dpll_lock_dumpit+0x13/0x20 [52804.642747] which lock already depends on the new lock. [52804.643551] the existing dependency chain (in reverse order) is: [52804.644259] -> #1 (dpll_lock){+.+.}-{3:3}: [52804.644836] lock_acquire+0x174/0x3e0 [52804.645271] __mutex_lock+0x119/0x1150 [52804.645723] dpll_lock_dumpit+0x13/0x20 [52804.646169] genl_start+0x266/0x320 [52804.646578] __netlink_dump_start+0x321/0x450 [52804.647056] genl_family_rcv_msg_dumpit+0x155/0x1e0 [52804.647575] genl_rcv_msg+0x1ed/0x3b0 [52804.648001] netlink_rcv_skb+0xdc/0x210 [52804.648440] genl_rcv+0x24/0x40 [52804.648831] netlink_unicast+0x2f1/0x490 [52804.649290] netlink_sendmsg+0x36d/0x660 [52804.649742] __sock_sendmsg+0x73/0xc0 [52804.650165] __sys_sendto+0x184/0x210 [52804.650597] __x64_sys_sendto+0x72/0x80 [52804.651045] do_syscall_64+0x6f/0x140 [52804.651474] entry_SYSCALL_64_after_hwframe+0x46/0x4e [52804.652001] -> #0 (nlk_cb_mutex-GENERIC){+.+.}-{3:3}: [52804.652650] check_prev_add+0x1ae/0x1280 [52804.653107] __lock_acquire+0x1ed3/0x29a0 [52804.653559] lock_acquire+0x174/0x3e0 [52804.653984] __mutex_lock+0x119/0x1150 [52804.654423] netlink_dump+0xb3/0x780 [52804.654845] __netlink_dump_start+0x389/0x450 [52804.655321] genl_family_rcv_msg_dumpit+0x155/0x1e0 [52804.655842] genl_rcv_msg+0x1ed/0x3b0 [52804.656272] netlink_rcv_skb+0xdc/0x210 [52804.656721] genl_rcv+0x24/0x40 [52804.657119] netlink_unicast+0x2f1/0x490 [52804.657570] netlink_sendmsg+0x36d/0x660 [52804.658022] __sock_sendmsg+0x73/0xc0 [52804.658450] __sys_sendto+0x184/0x210 [52804.658877] __x64_sys_sendto+0x72/0x80 [52804.659322] do_syscall_64+0x6f/0x140 [52804.659752] entry_SYSCALL_64_after_hwframe+0x46/0x4e [52804.660281] other info that might help us debug this: [52804.661077] Possible unsafe locking scenario: [52804.661671] CPU0 CPU1 [52804.662129] ---- ---- [52804.662577] lock(dpll_lock); [52804.662924] lock(nlk_cb_mutex-GENERIC); [52804.663538] lock(dpll_lock); [52804.664073] lock(nlk_cb_mutex-GENERIC); [52804.664490] The issue as follows: __netlink_dump_start() calls control->start(cb) with nlk->cb_mutex held. In control->start(cb) the dpll_lock is taken. Then nlk->cb_mutex is released and taken again in netlink_dump(), while dpll_lock still being held. That leads to ABBA deadlock when another CPU races with the same operation. Fix this by moving dpll_lock taking into dumpit() callback which ensures correct lock taking order. Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions") Signed-off-by: Jiri Pirko Reviewed-by: Vadim Fedorenko --- drivers/dpll/dpll_netlink.c | 20 ++++++-------------- drivers/dpll/dpll_nl.c | 4 ---- 2 files changed, 6 insertions(+), 18 deletions(-) diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c index 314bb3775465..4ca9ad16cd95 100644 --- a/drivers/dpll/dpll_netlink.c +++ b/drivers/dpll/dpll_netlink.c @@ -1199,6 +1199,7 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) unsigned long i; int ret = 0; + mutex_lock(&dpll_lock); xa_for_each_marked_start(&dpll_pin_xa, i, pin, DPLL_REGISTERED, ctx->idx) { if (!dpll_pin_available(pin)) @@ -1218,6 +1219,8 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) } genlmsg_end(skb, hdr); } + mutex_unlock(&dpll_lock); + if (ret == -EMSGSIZE) { ctx->idx = i; return skb->len; @@ -1373,6 +1376,7 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) unsigned long i; int ret = 0; + mutex_lock(&dpll_lock); xa_for_each_marked_start(&dpll_device_xa, i, dpll, DPLL_REGISTERED, ctx->idx) { hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, @@ -1389,6 +1393,8 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) } genlmsg_end(skb, hdr); } + mutex_unlock(&dpll_lock); + if (ret == -EMSGSIZE) { ctx->idx = i; return skb->len; @@ -1439,20 +1445,6 @@ dpll_unlock_doit(const struct genl_split_ops *ops, struct sk_buff *skb, mutex_unlock(&dpll_lock); } -int dpll_lock_dumpit(struct netlink_callback *cb) -{ - mutex_lock(&dpll_lock); - - return 0; -} - -int dpll_unlock_dumpit(struct netlink_callback *cb) -{ - mutex_unlock(&dpll_lock); - - return 0; -} - int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb, struct genl_info *info) { diff --git a/drivers/dpll/dpll_nl.c b/drivers/dpll/dpll_nl.c index eaee5be7aa64..1e95f5397cfc 100644 --- a/drivers/dpll/dpll_nl.c +++ b/drivers/dpll/dpll_nl.c @@ -95,9 +95,7 @@ static const struct genl_split_ops dpll_nl_ops[] = { }, { .cmd = DPLL_CMD_DEVICE_GET, - .start = dpll_lock_dumpit, .dumpit = dpll_nl_device_get_dumpit, - .done = dpll_unlock_dumpit, .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, }, { @@ -129,9 +127,7 @@ static const struct genl_split_ops dpll_nl_ops[] = { }, { .cmd = DPLL_CMD_PIN_GET, - .start = dpll_lock_dumpit, .dumpit = dpll_nl_pin_get_dumpit, - .done = dpll_unlock_dumpit, .policy = dpll_pin_get_dump_nl_policy, .maxattr = DPLL_A_PIN_ID, .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP,