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 X-Spam-Level: X-Spam-Status: No, score=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEDFEC64E90 for ; Fri, 20 Nov 2020 12:50:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB91D22240 for ; Fri, 20 Nov 2020 12:50:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728235AbgKTMt7 (ORCPT ); Fri, 20 Nov 2020 07:49:59 -0500 Received: from mail-lf1-f67.google.com ([209.85.167.67]:37049 "EHLO mail-lf1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727761AbgKTMt5 (ORCPT ); Fri, 20 Nov 2020 07:49:57 -0500 Received: by mail-lf1-f67.google.com with SMTP id s30so13295569lfc.4; Fri, 20 Nov 2020 04:49:55 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=ihaqIlNyoXPWgNUx0pqd6VTxIMabScCyo7XaTtTbQ6k=; b=fqGOWhH2PV1hwBO7ccVACQK7sEWIw7TnqdVugoL0bFbzoNLGYwY6L+8wnTcEGPg0ba Y27Oih8srfzPqv/P0IuPQIetNDp+8Z+rgWuF8U7IBQ4GOK2N7WkQV0fGDqlGtVknfM/8 PnCggmalCZVfUKCtYGbTNtlQKk97FLxi+J6DTbtXjlzUxm6fpGxF32pdYGdaOMpsBnjI 5rirdX0sjDZCvsxRAqAymI3Yz5g0KRM8hYQt99MkbJnuMRTeeEYc//VhTnprGzSlykAa lDuiKS74jkyR1+D3FEWPVGPcOuLg/SK2FmvJZxEFnrO3FuRzIWYNlTxBuPdBmMasB7a/ QvYg== X-Gm-Message-State: AOAM530vTbzFGH2oGQBu2KgUqO4MJrXlE+60KpJF+Da7fRLJyF8XJl// VVbm1vlY7JMP6xlOJ+S7DD0= X-Google-Smtp-Source: ABdhPJwhIKBQ9azhAbSVWT0L5aAOQm6FWyfUQCXxX/5MNNYPLDo1FPdvCXE3+ytVP7hoUjJA+xzVpA== X-Received: by 2002:ac2:44ac:: with SMTP id c12mr8648105lfm.602.1605876594084; Fri, 20 Nov 2020 04:49:54 -0800 (PST) Received: from xi.terra (c-beaee455.07-184-6d6c6d4.bbcust.telenor.se. [85.228.174.190]) by smtp.gmail.com with ESMTPSA id z4sm271546ljh.55.2020.11.20.04.49.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Nov 2020 04:49:53 -0800 (PST) Received: from johan by xi.terra with local (Exim 4.93.0.4) (envelope-from ) id 1kg5rR-0007pd-Qp; Fri, 20 Nov 2020 13:49:57 +0100 Date: Fri, 20 Nov 2020 13:49:57 +0100 From: Johan Hovold To: "tiantao (H)" , Thomas Gleixner Cc: Johan Hovold , Tian Tao , gregkh@linuxfoundation.org, jirislaby@kernel.org, afaerber@suse.de, manivannan.sadhasivam@linaro.org, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tty: serial: replace spin_lock_irqsave by spin_lock in hard IRQ Message-ID: References: <1605776489-16283-1-git-send-email-tiantao6@hisilicon.com> <9ce93d7b-f769-58ed-e6bf-95c34bd0123e@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9ce93d7b-f769-58ed-e6bf-95c34bd0123e@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 20, 2020 at 07:25:03PM +0800, tiantao (H) wrote: > 在 2020/11/20 16:23, Johan Hovold 写道: > > On Thu, Nov 19, 2020 at 05:01:29PM +0800, Tian Tao wrote: > >> The code has been in a irq-disabled context since it is hard IRQ. There > >> is no necessity to do it again. > >> > >> Signed-off-by: Tian Tao > >> --- > >> drivers/tty/serial/owl-uart.c | 5 ++--- > >> 1 file changed, 2 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c > >> index c149f8c3..472fdaf 100644 > >> --- a/drivers/tty/serial/owl-uart.c > >> +++ b/drivers/tty/serial/owl-uart.c > >> @@ -251,10 +251,9 @@ static void owl_uart_receive_chars(struct uart_port *port) > >> static irqreturn_t owl_uart_irq(int irq, void *dev_id) > >> { > >> struct uart_port *port = dev_id; > >> - unsigned long flags; > >> u32 stat; > >> > >> - spin_lock_irqsave(&port->lock, flags); > >> + spin_lock(&port->lock); > > > > Same thing here; this will break with forced irq threading (i.e. > > "threadirqs") since the console code can still end up being called from > > interrupt context. > As the following code shows, owl_uart_irq does not run in the irq > threading context. > ret = request_irq(port->irq, owl_uart_irq, IRQF_TRIGGER_HIGH, > "owl-uart", port); > if (ret) > return ret; It still runs in a thread when interrupts are forced to be threaded using the kernel parameter "threadirqs". We just had a revert of a change like yours after lockdep reported the resulting lock inversion with forced interrupt threading. Whether drivers should have to care about "threadirqs" is a somewhat different question. Not sure how that's even supposed to work generally unless we mass-convert drivers to spin_lock_irqsave() (or mark their interrupts IRQF_NO_THREAD). Thomas, any comments? Johan 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 X-Spam-Level: X-Spam-Status: No, score=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0252C5519F for ; Fri, 20 Nov 2020 12:51:16 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6087422227 for ; Fri, 20 Nov 2020 12:51:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="E6WOn9Yu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6087422227 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7RMgcwwVP9r1TPMjM/+UlRxALSyBgRZa11D69J4TR2U=; b=E6WOn9Yu8Gt9kpXcHGYgKI8Bk c3Pg6/Oj3rNKg3DAOHSNrI94/NDS/3t8KDxzFC7WVsw5/XvpLrV3x0x2YFHCVgyUPCch6UVmDATET FYIR8T38CLHOu4WUBjm9DtL2dUYqc72tL2HpD9eKlwH6YXmI0QoWEHqsKEEPDDeBl547Gq70Rr3Bf 6BUxixLnqNoRTJ5K6XO0Y/8uZLU9aoqCSX8BVaS0fI9kx4p46EQjPsGq7JUk+k1CvuZqOcQMczwCz E+BGxLavpcicP3oA1aCmD3O4M80HdJ0Im/I7+4u6W2RxXFyLq4qs9oPGKxhkQIYSrLDonguc88QTo xdlx3JAxg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kg5rT-00009v-3u; Fri, 20 Nov 2020 12:49:59 +0000 Received: from mail-lf1-f67.google.com ([209.85.167.67]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kg5rQ-00009Q-7l for linux-arm-kernel@lists.infradead.org; Fri, 20 Nov 2020 12:49:57 +0000 Received: by mail-lf1-f67.google.com with SMTP id s30so13295566lfc.4 for ; Fri, 20 Nov 2020 04:49:55 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=ihaqIlNyoXPWgNUx0pqd6VTxIMabScCyo7XaTtTbQ6k=; b=tFR/KKZTv8CedU6HW7MY10bb1bXFXyHtjpYBEvcNAT5+2AVvdJHALbHk1ZEm42xKbX IeW7c2MK7U9KOFgQiaCgeEaJf79Ekvq+JdCNdBfHHVP8l1G89Qs7idRFJvm1oIR34l4l 19P+zysUB+91i7Pur85lUkmJbiZynGbVu8OdOtW1ztK2ixQRv/+/n8pQrwLkrdQkQw+H hA4Stw0YI2cHr1PFR8quTMvnofKG+397ca1/bPfXW3F/Q5EukLfegc0MFKvbhh84nxZg MUDsLYCzK0b/VxnxX2I/2jjWMemVP/gYH2IATTUuDQPMsaz/uvTcpKMnOVQDOiCpxipS tcbw== X-Gm-Message-State: AOAM530qtB8EZpQF332bjzPKAL9ZeaAwbiHbRHVy6dI+LDIY1CSqwDuS ITIybAFj2HbA4EqUbm6fD/I= X-Google-Smtp-Source: ABdhPJwhIKBQ9azhAbSVWT0L5aAOQm6FWyfUQCXxX/5MNNYPLDo1FPdvCXE3+ytVP7hoUjJA+xzVpA== X-Received: by 2002:ac2:44ac:: with SMTP id c12mr8648105lfm.602.1605876594084; Fri, 20 Nov 2020 04:49:54 -0800 (PST) Received: from xi.terra (c-beaee455.07-184-6d6c6d4.bbcust.telenor.se. [85.228.174.190]) by smtp.gmail.com with ESMTPSA id z4sm271546ljh.55.2020.11.20.04.49.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Nov 2020 04:49:53 -0800 (PST) Received: from johan by xi.terra with local (Exim 4.93.0.4) (envelope-from ) id 1kg5rR-0007pd-Qp; Fri, 20 Nov 2020 13:49:57 +0100 Date: Fri, 20 Nov 2020 13:49:57 +0100 From: Johan Hovold To: "tiantao (H)" , Thomas Gleixner Subject: Re: [PATCH] tty: serial: replace spin_lock_irqsave by spin_lock in hard IRQ Message-ID: References: <1605776489-16283-1-git-send-email-tiantao6@hisilicon.com> <9ce93d7b-f769-58ed-e6bf-95c34bd0123e@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <9ce93d7b-f769-58ed-e6bf-95c34bd0123e@huawei.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201120_074956_380658_B4E68C29 X-CRM114-Status: GOOD ( 22.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: gregkh@linuxfoundation.org, Johan Hovold , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, manivannan.sadhasivam@linaro.org, Tian Tao , jirislaby@kernel.org, afaerber@suse.de, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gRnJpLCBOb3YgMjAsIDIwMjAgYXQgMDc6MjU6MDNQTSArMDgwMCwgdGlhbnRhbyAoSCkgd3Jv dGU6Cj4g5ZyoIDIwMjAvMTEvMjAgMTY6MjMsIEpvaGFuIEhvdm9sZCDlhpnpgZM6Cj4gPiBPbiBU aHUsIE5vdiAxOSwgMjAyMCBhdCAwNTowMToyOVBNICswODAwLCBUaWFuIFRhbyB3cm90ZToKPiA+ PiBUaGUgY29kZSBoYXMgYmVlbiBpbiBhIGlycS1kaXNhYmxlZCBjb250ZXh0IHNpbmNlIGl0IGlz IGhhcmQgSVJRLiBUaGVyZQo+ID4+IGlzIG5vIG5lY2Vzc2l0eSB0byBkbyBpdCBhZ2Fpbi4KPiA+ Pgo+ID4+IFNpZ25lZC1vZmYtYnk6IFRpYW4gVGFvIDx0aWFudGFvNkBoaXNpbGljb24uY29tPgo+ ID4+IC0tLQo+ID4+ICAgZHJpdmVycy90dHkvc2VyaWFsL293bC11YXJ0LmMgfCA1ICsrLS0tCj4g Pj4gICAxIGZpbGUgY2hhbmdlZCwgMiBpbnNlcnRpb25zKCspLCAzIGRlbGV0aW9ucygtKQo+ID4+ Cj4gPj4gZGlmZiAtLWdpdCBhL2RyaXZlcnMvdHR5L3NlcmlhbC9vd2wtdWFydC5jIGIvZHJpdmVy cy90dHkvc2VyaWFsL293bC11YXJ0LmMKPiA+PiBpbmRleCBjMTQ5ZjhjMy4uNDcyZmRhZiAxMDA2 NDQKPiA+PiAtLS0gYS9kcml2ZXJzL3R0eS9zZXJpYWwvb3dsLXVhcnQuYwo+ID4+ICsrKyBiL2Ry aXZlcnMvdHR5L3NlcmlhbC9vd2wtdWFydC5jCj4gPj4gQEAgLTI1MSwxMCArMjUxLDkgQEAgc3Rh dGljIHZvaWQgb3dsX3VhcnRfcmVjZWl2ZV9jaGFycyhzdHJ1Y3QgdWFydF9wb3J0ICpwb3J0KQo+ ID4+ICAgc3RhdGljIGlycXJldHVybl90IG93bF91YXJ0X2lycShpbnQgaXJxLCB2b2lkICpkZXZf aWQpCj4gPj4gICB7Cj4gPj4gICAJc3RydWN0IHVhcnRfcG9ydCAqcG9ydCA9IGRldl9pZDsKPiA+ PiAtCXVuc2lnbmVkIGxvbmcgZmxhZ3M7Cj4gPj4gICAJdTMyIHN0YXQ7Cj4gPj4gICAKPiA+PiAt CXNwaW5fbG9ja19pcnFzYXZlKCZwb3J0LT5sb2NrLCBmbGFncyk7Cj4gPj4gKwlzcGluX2xvY2so JnBvcnQtPmxvY2spOwo+ID4gCj4gPiBTYW1lIHRoaW5nIGhlcmU7IHRoaXMgd2lsbCBicmVhayB3 aXRoIGZvcmNlZCBpcnEgdGhyZWFkaW5nIChpLmUuCj4gPiAidGhyZWFkaXJxcyIpIHNpbmNlIHRo ZSBjb25zb2xlIGNvZGUgY2FuIHN0aWxsIGVuZCB1cCBiZWluZyBjYWxsZWQgZnJvbQo+ID4gaW50 ZXJydXB0IGNvbnRleHQuCgo+IEFzIHRoZSBmb2xsb3dpbmcgY29kZSBzaG93cywgb3dsX3VhcnRf aXJxIGRvZXMgbm90IHJ1biBpbiB0aGUgaXJxIAo+IHRocmVhZGluZyBjb250ZXh0Lgo+ICAgcmV0 ID0gcmVxdWVzdF9pcnEocG9ydC0+aXJxLCBvd2xfdWFydF9pcnEsIElSUUZfVFJJR0dFUl9ISUdI LAo+ICAgICAgICAgICAgICAgICAgICAgICAgICAib3dsLXVhcnQiLCBwb3J0KTsKPiAgICAgICAg ICBpZiAocmV0KQo+ICAgICAgICAgICAgICAgICAgcmV0dXJuIHJldDsKCkl0IHN0aWxsIHJ1bnMg aW4gYSB0aHJlYWQgd2hlbiBpbnRlcnJ1cHRzIGFyZSBmb3JjZWQgdG8gYmUgdGhyZWFkZWQKdXNp bmcgdGhlIGtlcm5lbCBwYXJhbWV0ZXIgInRocmVhZGlycXMiLgoKV2UganVzdCBoYWQgYSByZXZl cnQgb2YgYSBjaGFuZ2UgbGlrZSB5b3VycyBhZnRlciBsb2NrZGVwIHJlcG9ydGVkIHRoZQpyZXN1 bHRpbmcgbG9jayBpbnZlcnNpb24gd2l0aCBmb3JjZWQgaW50ZXJydXB0IHRocmVhZGluZy4KCldo ZXRoZXIgZHJpdmVycyBzaG91bGQgaGF2ZSB0byBjYXJlIGFib3V0ICJ0aHJlYWRpcnFzIiBpcyBh IHNvbWV3aGF0CmRpZmZlcmVudCBxdWVzdGlvbi4gTm90IHN1cmUgaG93IHRoYXQncyBldmVuIHN1 cHBvc2VkIHRvIHdvcmsgZ2VuZXJhbGx5CnVubGVzcyB3ZSBtYXNzLWNvbnZlcnQgZHJpdmVycyB0 byBzcGluX2xvY2tfaXJxc2F2ZSgpIChvciBtYXJrIHRoZWlyCmludGVycnVwdHMgSVJRRl9OT19U SFJFQUQpLgoKVGhvbWFzLCBhbnkgY29tbWVudHM/CgpKb2hhbgoKX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxp c3QKbGludXgtYXJtLWtlcm5lbEBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZy YWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtYXJtLWtlcm5lbAo=