From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8B36D1C8618; Wed, 19 Mar 2025 14:39:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742395199; cv=none; b=ALsxJ7yYScM8y3YZ3ty1uWqVqIc6+xFAOcw5nH4kxsMIjtbo4WADH1TboCOTShE4mG4kVKAeRpUYpNRjBsJu1wqu+cHjZQo1+5MzeAwNbQgLzyfq3UhhEpuXpdD3UHBGv99MhP6SsnCJI0mcrSdgVnW0Iq4ofpUensCUnzevuoY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742395199; c=relaxed/simple; bh=kDIZvDqYvmYW8ax17i78/7aphxkRU2Y90nxhfHACy84=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pLy4VzvQKYKiPNchCgsTY/S9bmmjItC1pSq4/g4kOG1cRsrKj48z3VKbaSy/ocY3T+tf8B4bisi//19ngNbIlXuKzfE+TXr4gtg5HKsyhPfZa2P/DDgJiC3yXE5pHiPLF4cerNSlVMvdXnXCAGFbTckytTlFNPg70JTtAr5xW5k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=C0xi92E/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="C0xi92E/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 623C6C4CEE4; Wed, 19 Mar 2025 14:39:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1742395199; bh=kDIZvDqYvmYW8ax17i78/7aphxkRU2Y90nxhfHACy84=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C0xi92E/FZkuYGrpGrzXOZcvXYyMip4a4yaQjidNGXLdWxsLccjt/YTpHgLOUGUQt ytuZYeng2pIqq+r1KNTYgLSnML4ut/UN7EJUAnUmdX8w4OZWqNKzN5diVccWbEpGHb a2KmjiIIGRWbkHaQvTLie7+sbbP0iDPDC7v5EIfA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vineeth Vijayan , Eric Farman , Peter Oberparleiter , Vasily Gorbik , Sasha Levin Subject: [PATCH 6.6 061/166] s390/cio: Fix CHPID "configure" attribute caching Date: Wed, 19 Mar 2025 07:30:32 -0700 Message-ID: <20250319143021.660076820@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250319143019.983527953@linuxfoundation.org> References: <20250319143019.983527953@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Oberparleiter [ Upstream commit 32ae4a2992529e2c7934e422035fad1d9b0f1fb5 ] In some environments, the SCLP firmware interface used to query a CHPID's configured state is not supported. On these environments, rapidly reading the corresponding sysfs attribute produces inconsistent results: $ cat /sys/devices/css0/chp0.00/configure cat: /sys/devices/css0/chp0.00/configure: Operation not supported $ cat /sys/devices/css0/chp0.00/configure 3 This occurs for example when Linux is run as a KVM guest. The inconsistency is a result of CIO using cached results for generating the value of the "configure" attribute while failing to handle the situation where no data was returned by SCLP. Fix this by not updating the cache-expiration timestamp when SCLP returns no data. With the fix applied, the system response is consistent: $ cat /sys/devices/css0/chp0.00/configure cat: /sys/devices/css0/chp0.00/configure: Operation not supported $ cat /sys/devices/css0/chp0.00/configure cat: /sys/devices/css0/chp0.00/configure: Operation not supported Reviewed-by: Vineeth Vijayan Reviewed-by: Eric Farman Tested-by: Eric Farman Signed-off-by: Peter Oberparleiter Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin --- drivers/s390/cio/chp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/s390/cio/chp.c b/drivers/s390/cio/chp.c index 5440f285f3494..7e00c061538db 100644 --- a/drivers/s390/cio/chp.c +++ b/drivers/s390/cio/chp.c @@ -661,7 +661,8 @@ static int info_update(void) if (time_after(jiffies, chp_info_expires)) { /* Data is too old, update. */ rc = sclp_chp_read_info(&chp_info); - chp_info_expires = jiffies + CHP_INFO_UPDATE_INTERVAL ; + if (!rc) + chp_info_expires = jiffies + CHP_INFO_UPDATE_INTERVAL; } mutex_unlock(&info_lock); -- 2.39.5