From patchwork Mon Mar 11 06:54:25 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shinichiro Kawasaki X-Patchwork-Id: 13588319 Received: from esa6.hgst.iphmx.com (esa6.hgst.iphmx.com [216.71.154.45]) (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 2E38110FA for ; Mon, 11 Mar 2024 06:54:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.71.154.45 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710140077; cv=none; b=kUgJZtEBt+70NA7aSv0vQRi8JzyWvhNF58aGv2iT3KYtmBiBAn/DbotlPRotIwFKORMvrc/7Is7iCRnx69Qj+AgqwaGocSQtvaY7D4CjHtCJUqZkFi4TxF7/R/DRTcVrFEw1A28JcC3cmgNXB1B6W4Lct55cYwdUSxZJLLEteVs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710140077; c=relaxed/simple; bh=sFd4n4HachYGv1YT7DWo8m3BNQL9cqEdluNkh5Nqe/Q=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=QVq23r016zXaFvaFArLTICWBmKVLDL2hTzRAyOyKYxL8lBPdajI1t+5lYC0dHoB2fTTwwJ1M0kRrsVRaGfoip0xvqr6ZgTOgfPhw6wvrf1Gci44BgofThvSCx1Jej+X/Qk+URYgRYS67PFN6OpMX5meyOfAnJ2gCbiJKbGHne4s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=wdc.com; spf=pass smtp.mailfrom=wdc.com; dkim=pass (2048-bit key) header.d=wdc.com header.i=@wdc.com header.b=gaWHsUjq; arc=none smtp.client-ip=216.71.154.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=wdc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=wdc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=wdc.com header.i=@wdc.com header.b="gaWHsUjq" DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1710140075; x=1741676075; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=sFd4n4HachYGv1YT7DWo8m3BNQL9cqEdluNkh5Nqe/Q=; b=gaWHsUjqvU1cVa/EkDSvzBzcGeJBBoAmXTfuNMA0NsiO/JcikD9uxvpu 8Q80McrodZ9vUsI/ieq8b9GuuQTZAvc3UeSmc6gTzNELj3jv1brpD3B4s MX6JCSMPxQhUsm1g4xbQ8LGbBzn3QnH3GQtrobC5tZP+0L5r1BN6/Eu10 TNPX4uKi9lk2rpT8KaVp3oY1aT/OLrDZZpCBZ2WxGgBIakvrWNwk/nMzl GvntNR+sRggbUpUefvIyVDhM0RJK+U/9PjeKoBUTgTdU12pb/RqAJV3QB tKBz4hnEgjTfnAGU7Wp3/ydX76/DnQRGtK61NG238KRfApHKDC9MaLF66 w==; X-CSE-ConnectionGUID: dhjHTNl2RKav2B2kyiX+dw== X-CSE-MsgGUID: JRAml5uOQKGtkIyQF6yK4A== X-IronPort-AV: E=Sophos;i="6.07,115,1708358400"; d="scan'208";a="11270701" Received: from uls-op-cesaip02.wdc.com (HELO uls-op-cesaep02.wdc.com) ([199.255.45.15]) by ob1.hgst.iphmx.com with ESMTP; 11 Mar 2024 14:54:28 +0800 IronPort-SDR: lY9lVT4jgEvH1sIKBSE3poyv4t4DQRCPYfsc46yfcrsAO7sDEVCuH4SG+QWjCjnYzyGff1ZCa+ UbRjsbv6MoBQ== Received: from uls-op-cesaip02.wdc.com ([10.248.3.37]) by uls-op-cesaep02.wdc.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 10 Mar 2024 22:57:51 -0700 IronPort-SDR: +/7+4XnqWmU0Lv6EvaSOBKdRlZ+ZicPXUQvNszSdhCn6/eS9LUbHCudHcfz9t5Nf+pKacejfMD kAw82Kkjb/6g== WDCIronportException: Internal Received: from unknown (HELO shindev.ssa.fujisawa.hgst.com) ([10.149.66.30]) by uls-op-cesaip02.wdc.com with ESMTP; 10 Mar 2024 23:54:27 -0700 From: Shin'ichiro Kawasaki To: linux-scsi@vger.kernel.org, "Martin K . Petersen" , Douglas Gilbert Cc: Shin'ichiro Kawasaki Subject: [PATCH RFC 0/2] scsi: scsi_debug: Allow parameter changes through sysfs Date: Mon, 11 Mar 2024 15:54:25 +0900 Message-ID: <20240311065427.3006023-1-shinichiro.kawasaki@wdc.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Some of the blktests users run tests using kernels with built-in modules to run tests easier and quicker. For that reason, it is desirable to run tests with the built-in scsi_debug [1]. However, some of the scsi_debug parameters can be modified only at module load, as module parameters. They are visible as sysfs attribute files, but they are read-only and not writable. There are ten, read-only scsi_debug parameters used in blktests [2]. Because of these parameters, eight test cases are skipped when scsi_debug is built-in [3]. The values of those parameters are kept as global variables and referred to in many places. Changes in the parameter values affect live scsi_debug hosts and cause various troubles. That is why the parameters are read-only. I once tried to make the parameters non-global and unique to each host, but found this approach will need large code changes in scsi_debug. To minimize the code changes for such parameter changes, I propose to allow the parameter changes "only when scsi_debug has no hosts." Users need to remove all hosts before changing the parameters. With this restriction, users can run tests with any, desired parameter values using the built-in scsi_debug. This series shows how the code will change with this approach. I chose dev_size_mb as the example parameter, which is referred to in multiple blktests test cases. The first patch in the series is preparation. The second patch makes dev_size_mb writable through sysfs only when there is no host. This change will allow the test case block/032 to run with the built-in scsi_debug. Corresponding blktests side changes are available on github [4]. The work for the other listed parameters is in progress. While the work is on going, I would like to ask for comments on this approach. Is this approach acceptable? Is there any other better way? [1] https://lore.kernel.org/linux-block/20220530130811.3006554-1-hch@lst.de/ [2] Parameters used in blktests which have read-only sysfs attribute files dev_size_mb sector_size lbpws lbpws10 dix dif zbc zone_cap_mb zone_size_mb zone_nr_conv [3] Test cases skipped with built-in scsi_debug block/009 block/025 block/028 block/032 loop/004 zbd/008 zbd/009 zbd/010 [4] https://github.com/kawasaki/blktests/tree/scsi_debug Shin'ichiro Kawasaki (2): scsi: scsi_debug: Factor out initialization of size parameters scsi: scsi_debug: Allow dev_size_mb changes through sysfs drivers/scsi/scsi_debug.c | 91 ++++++++++++++++++++++++++++++--------- 1 file changed, 70 insertions(+), 21 deletions(-)