From mboxrd@z Thu Jan 1 00:00:00 1970 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 8DD81C4332F for ; Tue, 13 Dec 2022 22:07:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236873AbiLMWGs (ORCPT ); Tue, 13 Dec 2022 17:06:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236813AbiLMWGi (ORCPT ); Tue, 13 Dec 2022 17:06:38 -0500 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79B4EEE3D; Tue, 13 Dec 2022 14:06:36 -0800 (PST) Received: by mail-pl1-x62a.google.com with SMTP id m4so1344998pls.4; Tue, 13 Dec 2022 14:06:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:from:to:cc:subject :date:message-id:reply-to; bh=3P8+fmlFT4yhtE4PFHqszJb/OdQRA5x5lH9d2KNq6fg=; b=VDgCfOPPh3Dez2V702FiW9sWEczCvVpOadPaJjKhQyxQ+cDVzaUSnvRGyHzasyV8YE onfVcH71E8dx5ZCBL0Fn8EjDSfvhQ1FsFFK4k9qig2n7zJw9JydGDP9FH6Cvhd3MSRqd 1lmT5jwGpDC4HoM7TZqdhc5ptbd/hzV0wcPRrTSTSq8f4SUjAG4A4h/TVJOwSbpPwkGh TTgd8BwWWHx6wB8wuBfirhcUD0IQ66VuSNt9ogoMkqepSxPw+xeq8Sf2Oc0n6QOvNAtT f5YUH9K30XHxAET1u0bjHllNnx3p/PzYgZtvLLplXUoLdqRh1USs4tiZw4aqDPdkmwaW q4VA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=3P8+fmlFT4yhtE4PFHqszJb/OdQRA5x5lH9d2KNq6fg=; b=KqIgqazbnTO/V75+hzgX7HO7H6NPT14Q7UcTcoU/qmUQGaDAAwF2C/f+ljk4G1/Hhb tbryPfvgtv9FRPQKrkOg1RWHzqY4+rHSeckARfID7PVUhBCb/PQmZO1XTasXyGeV4wP2 YQeACo2fBiYdDXJgBQL8MqhlsY6Cf5QEmaGO1/amKw87TUka/nISZwawAAuo3Bd8Q9Y5 Q2/kXOGWVDPW0JHFupRqRVTbSzMABRZWFFHfv4TTdQxTUxA+3W3XnzLF4rPy1Bjjsi4E ncmNgV2Qprp0dsgDNWVFitpxUzo5leIKPIgV0hR5tYVYQbZZKSaZ7HOQvEoe0SMmEcOH +fnw== X-Gm-Message-State: ANoB5pnkXDMSQU+/IloHIb6uNYJxfC8NKTmFibhKoLp8GtSEE3uSB+fj mQEhUc7Exif+mV31tExWcRjDue34+co= X-Google-Smtp-Source: AA0mqf5+My1KMnfxezazmOJwrZzXmTiSo0UQgisY3Zj4etX6aQs0nTfM1azYODLSujjXbo1mcsHkMg== X-Received: by 2002:a17:903:4cd:b0:189:c57c:9a19 with SMTP id jm13-20020a17090304cd00b00189c57c9a19mr20114453plb.58.1670969195803; Tue, 13 Dec 2022 14:06:35 -0800 (PST) Received: from [192.168.0.128] ([98.97.42.38]) by smtp.googlemail.com with ESMTPSA id b5-20020a170902650500b00186a437f4d7sm369916plk.147.2022.12.13.14.06.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Dec 2022 14:06:35 -0800 (PST) Message-ID: Subject: Re: [PATCH v2 net-next 2/3] net: dsa: mv88e6xxx: disable hold of chip lock for handling From: Alexander H Duyck To: "Hans J. Schultz" , davem@davemloft.net, kuba@kernel.org Cc: netdev@vger.kernel.org, Andrew Lunn , Florian Fainelli , Vladimir Oltean , Eric Dumazet , Paolo Abeni , open list Date: Tue, 13 Dec 2022 14:06:33 -0800 In-Reply-To: <20221213174650.670767-3-netdev@kapio-technology.com> References: <20221213174650.670767-1-netdev@kapio-technology.com> <20221213174650.670767-3-netdev@kapio-technology.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4 (3.44.4-2.fc36) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 2022-12-13 at 18:46 +0100, Hans J. Schultz wrote: > As functions called under the interrupt handler will need to take the > netlink lock, we need to release the chip lock before calling those > functions as otherwise double lock deadlocks will occur as userspace > calls towards the driver often take the netlink lock and then the > chip lock. >=20 > The deadlock would look like: >=20 > Interrupt handler: chip lock taken, but cannot take netlink lock as > userspace config call has netlink lock. > Userspace config: netlink lock taken, but cannot take chip lock as > the interrupt handler has the chip lock. >=20 > Signed-off-by: Hans J. Schultz Just to confirm, in order to see the deadlocks I would imagine you need something in the tracepoints that is taking the netlink lock? If so you might want to reference the commit that switched out the dev_err_ratelimited for the tracepoints 8646384d80f3 ("net: dsa: mv88e6xxx: replace ATU violation prints with trace points") so that this patch can be found an applied to any kernels that pull in those tracepoints. > --- > drivers/net/dsa/mv88e6xxx/global1_atu.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) >=20 > diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv= 88e6xxx/global1_atu.c > index 61ae2d61e25c..34203e112eef 100644 > --- a/drivers/net/dsa/mv88e6xxx/global1_atu.c > +++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c > @@ -409,11 +409,11 @@ static irqreturn_t mv88e6xxx_g1_atu_prob_irq_thread= _fn(int irq, void *dev_id) > =20 > err =3D mv88e6xxx_g1_read_atu_violation(chip); > if (err) > - goto out; > + goto out_unlock; > =20 > err =3D mv88e6xxx_g1_read(chip, MV88E6XXX_G1_ATU_OP, &val); > if (err) > - goto out; > + goto out_unlock; > =20 > err =3D mv88e6xxx_g1_atu_fid_read(chip, &fid); > if (err) > @@ -421,11 +421,13 @@ static irqreturn_t mv88e6xxx_g1_atu_prob_irq_thread= _fn(int irq, void *dev_id) > =20 > err =3D mv88e6xxx_g1_atu_data_read(chip, &entry); > if (err) > - goto out; > + goto out_unlock; > =20 > err =3D mv88e6xxx_g1_atu_mac_read(chip, &entry); > if (err) > - goto out; > + goto out_unlock; > + > + mv88e6xxx_reg_unlock(chip); > =20 > spid =3D entry.state; > =20 > @@ -449,13 +451,13 @@ static irqreturn_t mv88e6xxx_g1_atu_prob_irq_thread= _fn(int irq, void *dev_id) > fid); > chip->ports[spid].atu_full_violation++; > } > - mv88e6xxx_reg_unlock(chip); > =20 > return IRQ_HANDLED; > =20 > -out: > +out_unlock: > mv88e6xxx_reg_unlock(chip); > =20 > +out: > dev_err(chip->dev, "ATU problem: error %d while handling interrupt\n", > err); > return IRQ_HANDLED; Reviewed-by: Alexander Duyck