From patchwork Mon Jul 24 22:41:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Elder X-Patchwork-Id: 13325392 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 206BEEB64DD for ; Mon, 24 Jul 2023 22:41:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231314AbjGXWlN (ORCPT ); Mon, 24 Jul 2023 18:41:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229485AbjGXWlM (ORCPT ); Mon, 24 Jul 2023 18:41:12 -0400 Received: from mail-io1-xd34.google.com (mail-io1-xd34.google.com [IPv6:2607:f8b0:4864:20::d34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 94ADC10C8 for ; Mon, 24 Jul 2023 15:41:10 -0700 (PDT) Received: by mail-io1-xd34.google.com with SMTP id ca18e2360f4ac-785ccf19489so256954139f.3 for ; Mon, 24 Jul 2023 15:41:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1690238470; x=1690843270; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=KeP2Bpkp9J7OOE4sWn2E6NWLqeXa4peAEEdE+9mQzSs=; b=uVBTiaICcqS0cbclHhojIy9A/rn1xLF2yWj0IT3eGwYot+z7UEEoFf8vl2QmbV5HZd oZMhnIVX0R9vxalzBDfEdnRYeggfqAWPp4oZ9iIRiYDirNYDPry665l3xLJOv4w9ndoV atAKzCpgip8LDAIXf6qHwji/s1g3JbuWcbuDNTbWkgkfmMoERf1A203T+0pmhikbtKdF ftEXpPbfnz5Wvvbtbdb23i/4K0J3WvPEoAfxj+wRypNZFJmdRvo094Efvgx0Uz399ao+ kY/uZo+vG0RSD0FXczITHgWRFih72r4lLaRNLR1zaoxfD2RRB/VOQFv104/3q7VyvDCy wRoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690238470; x=1690843270; 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=KeP2Bpkp9J7OOE4sWn2E6NWLqeXa4peAEEdE+9mQzSs=; b=Ck9IcnKx6NwePFc5K4SPWgbqkTtV2EjzMO0rZ/rWYYh3xVgmZ5Ddw1HidOqTKLfqsY 3PvMBFn/Rd3sH4U98VhZEkXa8ETZwuQzq+uBHT1raXbAmZfRJQ6UTQ934J+kHJcsTrs8 0kagx5arS5pn+dyBbnVo4uuaeb1o7lpJlu4CIU4gzwwZfQBwKS6PQZfO7VS9Tg9CP9j+ OKhtvR8AzoHG7QXte1xCM/zXYa2PhbYbQw4hUN1lrR55vKI9rU0lP2Y128GLaD8R1wsj DhHtHpexY+NbkIx2WTFgG8nTxOwGgKGsyOJGLPsNL56oGPfG7FxMp/jM0WJQtpry5MWf I67w== X-Gm-Message-State: ABy/qLYuBB10EwZu5jqymoVydiDcjpPmQpemVNmP6Tq7f70blcgEQ1RW LBlMufxPF7V3m0qoy6D7LhMptQ== X-Google-Smtp-Source: APBJJlEhDUh7RSS2Z2tTSspy5ELCXvyGnC/B2CaIbRlOt16SjoWMnBbRRS+8HrDzVxydj5/qeS3lcg== X-Received: by 2002:a5d:9b8f:0:b0:783:5e20:768d with SMTP id r15-20020a5d9b8f000000b007835e20768dmr1134570iom.18.1690238469994; Mon, 24 Jul 2023 15:41:09 -0700 (PDT) Received: from localhost.localdomain (c-98-61-227-136.hsd1.mn.comcast.net. [98.61.227.136]) by smtp.gmail.com with ESMTPSA id gv18-20020a0566382e5200b0042b1297468esm3103953jab.51.2023.07.24.15.41.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 15:41:08 -0700 (PDT) From: Alex Elder To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: dianders@chromium.org, caleb.connolly@linaro.org, mka@chromium.org, evgreen@chromium.org, andersson@kernel.org, quic_cpratapa@quicinc.com, quic_avuyyuru@quicinc.com, quic_jponduru@quicinc.com, quic_subashab@quicinc.com, elder@kernel.org, netdev@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH net] net: ipa: only reset hashed tables when supported Date: Mon, 24 Jul 2023 17:41:06 -0500 Message-Id: <20230724224106.1688869-1-elder@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Last year, the code that manages GSI channel transactions switched from using spinlock-protected linked lists to using indexes into the ring buffer used for a channel. Recently, Google reported seeing transaction reference count underflows occasionally during shutdown. Doug Anderson found a way to reproduce the issue reliably, and bisected the issue to the commit that eliminated the linked lists and the lock. The root cause was ultimately determined to be related to unused transactions being committed as part of the modem shutdown cleanup activity. Unused transactions are not normally expected (except in error cases). The modem uses some ranges of IPA-resident memory, and whenever it shuts down we zero those ranges. In ipa_filter_reset_table() a transaction is allocated to zero modem filter table entries. If hashing is not supported, hashed table memory should not be zeroed. But currently nothing prevents that, and the result is an unused transaction. Something similar occurs when we zero routing table entries for the modem. By preventing any attempt to clear hashed tables when hashing is not supported, the reference count underflow is avoided in this case. Note that there likely remains an issue with properly freeing unused transactions (if they occur due to errors). This patch addresses only the underflows that Google originally reported. Fixes: d338ae28d8a8 ("net: ipa: kill all other transaction lists") Cc: # 6.1.x Tested-by: Douglas Anderson Signed-off-by: Alex Elder --- drivers/net/ipa/ipa_table.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c index 510ff2dc8999a..cd81dd916c29e 100644 --- a/drivers/net/ipa/ipa_table.c +++ b/drivers/net/ipa/ipa_table.c @@ -311,16 +311,15 @@ static int ipa_filter_reset(struct ipa *ipa, bool modem) if (ret) return ret; - ret = ipa_filter_reset_table(ipa, IPA_MEM_V4_FILTER_HASHED, modem); - if (ret) - return ret; - ret = ipa_filter_reset_table(ipa, IPA_MEM_V6_FILTER, modem); + if (ret || !ipa_table_hash_support(ipa)) + return ret; + + ret = ipa_filter_reset_table(ipa, IPA_MEM_V4_FILTER_HASHED, modem); if (ret) return ret; - ret = ipa_filter_reset_table(ipa, IPA_MEM_V6_FILTER_HASHED, modem); - return ret; + return ipa_filter_reset_table(ipa, IPA_MEM_V6_FILTER_HASHED, modem); } /* The AP routes and modem routes are each contiguous within the @@ -329,11 +328,12 @@ static int ipa_filter_reset(struct ipa *ipa, bool modem) * */ static int ipa_route_reset(struct ipa *ipa, bool modem) { + bool hash_support = ipa_table_hash_support(ipa); struct gsi_trans *trans; u16 first; u16 count; - trans = ipa_cmd_trans_alloc(ipa, 4); + trans = ipa_cmd_trans_alloc(ipa, hash_support ? 4 : 2); if (!trans) { dev_err(&ipa->pdev->dev, "no transaction for %s route reset\n", @@ -350,12 +350,14 @@ static int ipa_route_reset(struct ipa *ipa, bool modem) } ipa_table_reset_add(trans, false, first, count, IPA_MEM_V4_ROUTE); - ipa_table_reset_add(trans, false, first, count, - IPA_MEM_V4_ROUTE_HASHED); - ipa_table_reset_add(trans, false, first, count, IPA_MEM_V6_ROUTE); - ipa_table_reset_add(trans, false, first, count, - IPA_MEM_V6_ROUTE_HASHED); + + if (hash_support) { + ipa_table_reset_add(trans, false, first, count, + IPA_MEM_V4_ROUTE_HASHED); + ipa_table_reset_add(trans, false, first, count, + IPA_MEM_V6_ROUTE_HASHED); + } gsi_trans_commit_wait(trans);