From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AABE0239E7E for ; Wed, 17 Jun 2026 12:01:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781697681; cv=none; b=eefaGDTZF7CKut3sDDQQ47PnJZosKYWRANlFdmzWDM/G0MVCWyTnrnEK2afstcx5H41lDG3W805Lzj2kRmRKur78yNu515KaKcN4dHy1lL9bkpqp50wB/dlbGf7CV8ROfRYJNV+anoxSINDvEjd+RZNfOCazhDa8P4b3iaLE1g0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781697681; c=relaxed/simple; bh=V8Rd5Kazt6RdByTHvi7A5NlbN3QZmnMAaXNMTi48UsM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iIu7NKeDglbSFw5hX0fsXIxz00NDV56vU+r0EMRXykZ2auhMg76B/Z5Qi6lmAQZtbwClG8PzhWq3FZ1LYOnSz4qH1T57X9g1DljEXkwtNzVatzgaIRI7ijtgzoGTlc6BOtscOyK38A465BxjZo1aoqosEa4K9XZazXdkpDvtNlE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=EH+SM2L7; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=alHDbJZR; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="EH+SM2L7"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="alHDbJZR" Received: from pps.filterd (m0279864.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 65H8Ug5Z1654590 for ; Wed, 17 Jun 2026 12:01:19 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= HWFTmDf2Lo/JzFBvBuJ3jnJkAJN1DvKDic5JBbNRhM0=; b=EH+SM2L75T+96RT+ y0NQDXIs79wQiFOhqnzBkBH+Nx8QNbD+PmpEx8agPEq8WFm70yh9kJnUg4Tn61zK nYS6xKdHKbeJECIOKm8/ccuSCPujrmCsGqtDEBVf5NVmworWjuWuOgdILCvo7d1t GR7uh930JJz4DbSJPWluarzhqplAYjFgWcRMBRnj6t9zK2m+9KRFM6PV8qVNCvrm Z0BETuOq/VsVdJuDPRGelW5SujHolHZaXitUMhNK/+eauwaebHmYBDhA1OWuF/aM JGCcI5o0MrOvsXrZer+H6QquISpDDIoo88M/hmHDjdrTP1ddVWAF7OICGn8CJJoi pLgFBQ== Received: from mail-ot1-f72.google.com (mail-ot1-f72.google.com [209.85.210.72]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4eueer2x6q-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Wed, 17 Jun 2026 12:01:18 +0000 (GMT) Received: by mail-ot1-f72.google.com with SMTP id 46e09a7af769-7e748b9a930so7402002a34.3 for ; Wed, 17 Jun 2026 05:01:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1781697678; x=1782302478; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=HWFTmDf2Lo/JzFBvBuJ3jnJkAJN1DvKDic5JBbNRhM0=; b=alHDbJZRUDfGbWuBWGFkxh0gTH6QG82wg78uUTZ70RXKoV0QexuSR/QFohsE11ulB/ 9Axmc0Bw9YuOlLGOe4Zx/kXzRYpmk9buWyNe2FnLnsgG3HjOJ/lTdMhzabiicZnhDHBd lA+jxDdSwNmFm5c7wkQf98UJVuq8n8PM4wgGjloVcv0o0lqFROIYLrPf/efqzkzn8m11 0xdCAuRZV1+AGj1NENtLVy04oUH0KjpDZhZywVvm3wUg8RdoZ8NmG/5HJbb3XboBKrd+ +dMYpRv3y9fjB1Knsf/oDrbx0Tf5VluPxmsycCKNyQGi66usTblTsbBknvrcqgQeoLUT cgVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781697678; x=1782302478; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=HWFTmDf2Lo/JzFBvBuJ3jnJkAJN1DvKDic5JBbNRhM0=; b=gtv079xe8aSaxP4kGDBiD/gZQo7oo3gvFLdE/k3pl0gnpwCginnOXXCwzum7L6+xXQ g+HGEFyp5PV00RxmueKr8EO4sjGAUp7A0xWhUlq1EhQGuVkQOk/n7OzDFrK221E5fwjZ OeBXjQT54CpfBjBcriKqjWRkZfvRvQ55/Y1SuuPe1Xwr3rP0528l2i6MCKmpmJB6o8nx 5tZmqr6m6k+VnCqFCROXuhQ4OWIKjhooYIhJiwT+BimjKg1FJERGdnUU3N04zxSqUdux pAicJ88yafH/4Q1rgJqtRroTc0jDyD4ny/B1JFp5iuvrSyU5nTrQAPXDW1DLSZRGLEYl kCWA== X-Forwarded-Encrypted: i=1; AFNElJ/hj+ZTzcLst4iBMWXWiC3EPVA3a/Wd+wlrIajqd1DLkEG8mse9dvnTh0CG1dzEuBjUVkQkoWEKnCNM788=@vger.kernel.org X-Gm-Message-State: AOJu0YwuPTWW/2v4n8cD2n506lXJw/0DANG3HRq4yNBCjEvAjTE20CWX 48vsCAMadg/bsIcnw7A1W7WaFaQrTjHEp+ZAPXYqErjdpcw/RWv/yipYfbwfPyCEv7avcs6kAo3 u26YLgjUBJKKhCdbMyGYUTJd5xzWOqYXn3b58+XwEQ8KIuh/z4FMYTBm3GFVaGBR5mSI= X-Gm-Gg: Acq92OE3H/Zxnnu5APB3a4CPy7W6Abue8o5SihCkVvU55WS2EceqGyfKrALf9tNVMVN qXGXBs61mK5zIfZnfcbRXWKmNf8d/m55zkhlAyT0DDcO5TQQuspvgE3PE5MpsI7x53fShx+iqoI aq4wAMJ8jL2FfPX53uq73buHLiaB8dSQz+f3NjrGFXcSNWaj7nt83nXKUUaQ0liRoTMPj9UIGxm 3NGE9//6ZPLf1jO40oR3qlR13LfMCkf3vuWK51wnonjwOwKsdG9kvFLJjf0qxtuAu9V5ZF4FTpE aOo0TAZpAk6ZTMxeQC4uLSuXU8k7CbDWitMeX5/nt08zwtgv7w9fP9npx3SWy72ixkL5xlb/oHK Hs3L1Z9oXx6b4FEup6x144hWhX6Qoyg== X-Received: by 2002:a05:6830:d11:b0:7e7:c1d:bf5b with SMTP id 46e09a7af769-7e90c99b2a8mr2639159a34.24.1781697677790; Wed, 17 Jun 2026 05:01:17 -0700 (PDT) X-Received: by 2002:a05:6830:d11:b0:7e7:c1d:bf5b with SMTP id 46e09a7af769-7e90c99b2a8mr2639081a34.24.1781697677143; Wed, 17 Jun 2026 05:01:17 -0700 (PDT) Received: from [192.168.69.208] (88-187-86-199.subs.proxad.net. [88.187.86.199]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606f26f309sm48890784f8f.14.2026.06.17.05.01.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 17 Jun 2026 05:01:16 -0700 (PDT) Message-ID: Date: Wed, 17 Jun 2026 14:01:15 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 5/6] serial: sb1250-duart: Switch to spinlock protection for shared resource Content-Language: en-US To: "Maciej W. Rozycki" , Thomas Bogendoerfer , Greg Kroah-Hartman , Jiri Slaby Cc: Elena Reshetova , David Windsor , Kees Cook , Hans Liljestrand , linux-mips@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org References: From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: 4PggtFKY7qQziqJ_CJx_Q1KvppU9z9-C X-Authority-Analysis: v=2.4 cv=Mr1iLWae c=1 sm=1 tr=0 ts=6a328c8e cx=c_pps a=+3WqYijBVYhDct2f5Fivkw==:117 a=4s3hRJSeHn4rkQlkrse1kQ==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=M51BFTxLslgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=BcPKCTjPAAAA:8 a=EUspDBNiAAAA:8 a=EbunRdXsnukT5RqbSTkA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=eYe2g0i6gJ5uXG_o6N4q:22 a=MNXww67FyIVnWKX2fotq:22 X-Proofpoint-GUID: 4PggtFKY7qQziqJ_CJx_Q1KvppU9z9-C X-Proofpoint-Spam-Info: AW1haW4tMjYwNjE3MDExNCBTYWx0ZWRfXxVzaBG9zTShR La0gZBsv7ZJv5DlawIs2mV3YI0A+DjbsOpSb6ktTQWLkELn0S/od1Mbci4JyBh7h5WfGK7NQHzk 5YYTEk6bjtDPdHTWJSzJeBg1Kogxwvk= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjE3MDExNCBTYWx0ZWRfX2JaBiEUT3+IF ezXejKfxNKuQV0GtjvFSMkU8UFwTpzHex8hkTKmyE9OWfsgFrMuZRBVKYsK/cJc6y3jSqdqCOHb ccjyDVxF1irv0yBBBgqSG2Es8GpMDlIzglmb99/DOg6WBvE/YU9GLUH5upzOwsiSbtpHbKUCE3L wpe7T911meVsiojCLE4z0TdCqzaxlR09lK+nuAwmkamof1bBmV344OAL9yzi+fZJRWBiH2jZXiY hFroQ5VKwaupAWzKiyYRh//RQ49tTu3x1bS+lMZIGUQVCXMh78m4dWHxmoaUv/ZGEH49ESjFYGe TLjAWXXU/2EtpG+U1iDpJzkx/eYgAM6aXiNA1oEl9kLP81hIVCzLGn/QuArTjVlI2b+4yQS1PBx 55ZdEx1BTdht9gYclMFg/K36m0gTs9WYwzYBqk0aiabjwCJsZsagMbC8W/WBlKxPyEg7AtQwLRL F9EkNQCLBgWRTVTaZjg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-17_01,2026-06-16_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 phishscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 adultscore=0 suspectscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606170114 On 25/5/26 01:12, Maciej W. Rozycki wrote: > The control register block is shared between DUART channels and so its > resource has to be requested by the first channel claimed and released > by the last one dropped. > > It is currently handled with an atomic counter, which however does not > protect against a situation where request_mem_region() has failed, but > another CPU has seen the map guard nonzero and refrained from calling > this function for another channel where it should have (and likely also > fail). This parallel execution scenario can in principle be arranged > via the TIOCSSERIAL ioctl. > > Switch to using an ordinary counter then and spinlock protection for the > counter updates along with the corresponding resource request/release > calls, so that the case described above is covered. > > Fixes: b45d52797432 ("sb1250-duart.c: SB1250 DUART serial support") > Signed-off-by: Maciej W. Rozycki > --- > New change in v2. > --- > drivers/tty/serial/sb1250-duart.c | 28 ++++++++++++++++++---------- > 1 file changed, 18 insertions(+), 10 deletions(-) Reviewed-by: Philippe Mathieu-Daudé