From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout.web.de (mout.web.de [217.72.192.78]) (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 E55F01D7E31; Fri, 26 Sep 2025 18:16:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.72.192.78 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758910579; cv=none; b=uBoTeAegmM2ulunU/sZIBCU02J2AV2EWtskxpUHWPUCsSBdMBxNPb0RAvuC0nENdosU3jCTMABYffd3CVRvWT8Yzs0u3NHXaDcvs09Vq0o4b7IQ74fzfollfhtIOU3cnz934SLUNsD+2W3dVrEhLUUbOb5Zo1oTEgjLhWZ+w3T4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758910579; c=relaxed/simple; bh=CP15thKib2R8+k5xSriEGbfQdYizPZTAvRCg91KReCE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=c521evfoeBvOQxymZe/iUV5aoZtuCZ8w+tLwf6VX7UvsoOVpMngBD3W6yI0Ow9wYwySesHdJomGRvFBMRNXFIq2ZLGDz3uYbAh90/xwGYlrveM7n5FCItqxGKQQUbVkQR2FrvbpVKqwDRi8mjmxddtY/CyRom+BM8hAgjNSspmM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=web.de; spf=pass smtp.mailfrom=web.de; dkim=pass (2048-bit key) header.d=web.de header.i=markus.elfring@web.de header.b=UjjSGDmK; arc=none smtp.client-ip=217.72.192.78 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=web.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=web.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=web.de header.i=markus.elfring@web.de header.b="UjjSGDmK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=web.de; s=s29768273; t=1758910567; x=1759515367; i=markus.elfring@web.de; bh=E7bujOx4DLPqZWlI88EeoZQECVrnfxfxTKQOIZYfXFk=; h=X-UI-Sender-Class:Message-ID:Date:MIME-Version:Subject:To:Cc: References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding:cc:content-transfer-encoding: content-type:date:from:message-id:mime-version:reply-to:subject: to; b=UjjSGDmKMNhinqObi/9/aMnoURgOynKmAmlpClh7bd6cijbMOrAuv/pX7OTFo4hD VJ6fMTZdEBQw9/HGZV8QCAiFH00ykuAvrO4FK8pfvis2LS9NZ4/MnqruNy75Co7dE 3BdHfaggo9amSSqkIM466kcqujKISTndRismn7MKMWv5g9DICKVv9vhSbxv+cl+Rb C7/7yyy5fN88QIbejFBIKB39B4U1jTVHOQMbqsjSJSbTjGA/TpjngN7omx6692BMq V18stSp1xSKbKllvOP2Xe7aHcQRafahZO6s7yFueWfl5QdJ+WovRrXbeS0d6g/10q ovublZK2YBjxd6bWng== X-UI-Sender-Class: 814a7b36-bfc1-4dae-8640-3722d8ec6cd6 Received: from [192.168.178.29] ([94.31.69.192]) by smtp.web.de (mrweb105 [213.165.67.124]) with ESMTPSA (Nemesis) id 1M2xrq-1v3Iux1ocO-00HEZy; Fri, 26 Sep 2025 20:16:07 +0200 Message-ID: Date: Fri, 26 Sep 2025 20:15:59 +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 08/29] arm_mpam: Add the class and component structures for firmware described ris To: James Morse , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: LKML , Amit Singh Tomar , Baisheng Gao , Baolin Wang , Ben Horgan , Carl Worth , Catalin Marinas , D Scott Phillips , Danilo Krummrich , Dave Martin , David Hildenbrand , Drew Fustini , Fenghua Yu , Greg Kroah-Hartman , Hanjun Guo , Jamie Iles , Jonathan Cameron , Koba Ko , Len Brown , Linu Cherian , Lorenzo Pieralisi , Peter Newman , "Rafael J. Wysocki" , Rob Herring , Rohit Mathew , Shanker Donthineni , Sudeep Holla , Shaopeng Tan , Wang ShaoBo , Will Deacon , Xin Hao References: <20250910204309.20751-9-james.morse@arm.com> <5a80cb91-6095-4f44-b576-53badc4575f5@web.de> <88f45c7f-9769-478b-9abd-749ec8f8d43b@arm.com> Content-Language: en-GB, de-DE From: Markus Elfring In-Reply-To: <88f45c7f-9769-478b-9abd-749ec8f8d43b@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:3maQEK1CnO2+DU9yp6HepDChC5p4ETeKuI0ApbsfHO+X/YgS2LC dRzrPIgIcL1KhPZ7dv0Oa8fyvEzmUMF3LO/0E10X2ePh7UkZTEOzX4loa0dXfGdb147k1jH Ze60pl3hfj+dqInxRRgQkBBWCGZmNtoZcZ99tcTJX2g86Yk1DyH7ZgaFQIcd6Gu8aci7yP7 1qxwDsznYILHFBXSEGYvg== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:5Isi+WWbkIM=;uYOd6aMpArFg9S1d4KDVSF55ybB 2TfQsO2yC6oqGvroJo2pEY0KRu83tcchE21fvkdzOu9Zsk16ATfR70a6GURsL5Pxvqi3mj2eO X0c/CVqbVNTzTWN8Km4+fVQVLabmAusrOW5adn7slPtKFmSVtWLs5wcKaOiRkoXK4Ancc3Wqm 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Mj711HaczTSfqQjEUWuwpQieQbbyxc9LWXRHliMEUL6WScozbrGSFkbxC85SE9+2v994tPOqG 9pUAkGCLStFryWj11phuew3CBLw2NpIsSOgWTnUw0uCjyF5uIOaTIYND5q+XaSzI/ >> =E2=80=A6 >>> +++ b/drivers/resctrl/mpam_devices.c >> =E2=80=A6 >>>> +int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx, >>> + enum mpam_class_types type, u8 class_id, int component_id) >>> +{ >>> + int err; >>> + >>> + mutex_lock(&mpam_list_lock); >>> + err =3D mpam_ris_create_locked(msc, ris_idx, type, class_id, >>> + component_id); >>> + mutex_unlock(&mpam_list_lock); >> =E2=80=A6 >> >> Under which circumstances would you become interested to apply a statem= ent >> like =E2=80=9Cguard(mutex)(&mpam_list_lock);=E2=80=9D? >> https://elixir.bootlin.com/linux/v6.17-rc5/source/include/linux/mutex.h= #L228 >=20 > None! The bit of this you cut out is a call to mpam_free_garbage() which= calls > synchronize_srcu(). That may sleep for a while. The whole point of the d= eferred free-ing > is it does not happen under the lock. The 'guard' magic means the compil= er gets to choose > when to call unlock. How does this feedback fit to the proposed addition of a mutex_lock()/mute= x_unlock() call combination (which might be achievable also with another programming = interface)? Regards, Markus