From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) (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 405C8433A8; Mon, 23 Jun 2025 14:51:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750690282; cv=none; b=uvz9qJb25GSFD8SmGijSMEDKseNU1y73CtaidfK/X/MpME89g5q9zijZ7RxWJEpjNBDFxgzxA9u8K5UJsEkD/DFqVvK7Crjgw3le39QdQou4ZrdXvE43mOwi3NNIdIz4uFbWloct/0JRkbIq1n+l/JYvThT3T1W/V2PInZu2blM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750690282; c=relaxed/simple; bh=bf8TIBVP9FgVJ5xoztwF4ppRrlZy1qaZ4xMEOoPGxTk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HRoGOjLclduccY5EabrNV49YgjUdWZvOccXklHZxS4DDYu43aN3MDbnv3uTp28MtRA2CnqiKHLn9ptRNAG23XPCS9UU+xV6muC/aCisCesZK6DX6Cxw+NzIQwNSwNalg/cIFtj7NHDUzFZKJPl8jNbxDgh3NG2SDmcJlfbu+lY4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=OToxZIIP; arc=none smtp.client-ip=198.175.65.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="OToxZIIP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1750690281; x=1782226281; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=bf8TIBVP9FgVJ5xoztwF4ppRrlZy1qaZ4xMEOoPGxTk=; b=OToxZIIPzMJnMOEm1orRee6NCbmoYeCWPjxh73/rfoijqLt/2jjAk9/N 6jACQBzVgl4yILxalpzLg+lq7ORQKWbFuVvLt10BLzanfkzYjEf4HB06e /KwKI0H/b5HsKUwvglFGIL3OMko81AGZ+XMuF7iN3TrEaThdV2PwAZgi7 9BVxJTMm74jj/bueBTsIvGW8HyRGEYincw9yFFSO0DB4oMOGaZaIYfR0u GBnyGwdz1pUqVmLnViDQRTaK+aWmM85dQHvmCjF/DQr21/Fvpfx7LZ3lC 2PZo751ZzIMssvcESQwKHguVUciC4AKcQIxhvnt1noV9DfwEclQG/S6bh g==; X-CSE-ConnectionGUID: 2sxCJPUGTdCsiUPA6If1gw== X-CSE-MsgGUID: sQMUtJvSRaOWenyMklUpuw== X-IronPort-AV: E=McAfee;i="6800,10657,11473"; a="52771202" X-IronPort-AV: E=Sophos;i="6.16,258,1744095600"; d="scan'208";a="52771202" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2025 07:51:20 -0700 X-CSE-ConnectionGUID: WxtZ9p+QR/GGBqrdHa+MUQ== X-CSE-MsgGUID: RRtWJ+zdTbm2BjGCpiAudA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,258,1744095600"; d="scan'208";a="152139979" Received: from msatwood-mobl.amr.corp.intel.com (HELO [10.125.108.178]) ([10.125.108.178]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2025 07:51:20 -0700 Message-ID: <99145cb3-1cb7-43ef-84bd-203616d00681@intel.com> Date: Mon, 23 Jun 2025 07:51:19 -0700 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 4/8] cxl/decoder: Drop pointless locking To: Dan Williams , linux-cxl@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Davidlohr Bueso , Jonathan Cameron , Alison Schofield , Vishal Verma , Ira Weiny References: <20250619050416.782871-1-dan.j.williams@intel.com> <20250619050416.782871-5-dan.j.williams@intel.com> Content-Language: en-US From: Dave Jiang In-Reply-To: <20250619050416.782871-5-dan.j.williams@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/18/25 10:04 PM, Dan Williams wrote: > cxl_dpa_rwsem coordinates changes to dpa allocation settings for a given > decoder. cxl_decoder_reset() has no need for a consistent snapshot of the > dpa settings since it is merely clearing out whatever was there previously. > > Otherwise, cxl_region_rwsem protects against 'reset' racing 'setup'. > > In preparationg for converting to rw_semaphore_acquire semantics, drop this > locking. > > Cc: Davidlohr Bueso > Cc: Jonathan Cameron > Cc: Dave Jiang > Cc: Alison Schofield > Cc: Vishal Verma > Cc: Ira Weiny > Signed-off-by: Dan Williams Reviewed-by: Dave Jiang > --- > drivers/cxl/core/hdm.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c > index 81556d12e9b8..e9cb34e30248 100644 > --- a/drivers/cxl/core/hdm.c > +++ b/drivers/cxl/core/hdm.c > @@ -914,7 +914,6 @@ static void cxl_decoder_reset(struct cxl_decoder *cxld) > "%s: out of order reset, expected decoder%d.%d\n", > dev_name(&cxld->dev), port->id, port->commit_end); > > - down_read(&cxl_dpa_rwsem); > ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id)); > ctrl &= ~CXL_HDM_DECODER0_CTRL_COMMIT; > writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id)); > @@ -923,7 +922,6 @@ static void cxl_decoder_reset(struct cxl_decoder *cxld) > writel(0, hdm + CXL_HDM_DECODER0_SIZE_LOW_OFFSET(id)); > writel(0, hdm + CXL_HDM_DECODER0_BASE_HIGH_OFFSET(id)); > writel(0, hdm + CXL_HDM_DECODER0_BASE_LOW_OFFSET(id)); > - up_read(&cxl_dpa_rwsem); > > cxld->flags &= ~CXL_DECODER_F_ENABLE; >