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 664322080CE; Tue, 18 Feb 2025 20:26:59 +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=1739910419; cv=none; b=bjT2Y44eyl+Whn+eWKyXH8u4UhlXtzGu/aEyNcIfsvdf35jBPO9Q0Sysx/D5coLbKt7HzIoPNtABACe+AM3qQqNnGFW2DQ5IxCKnI5vzfy9ttf+DtOgWMAyazeKamfL13Jj8z5hj+79+NaV32kEHT8kdol6wCbuMoYXTLQb7O6A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739910419; c=relaxed/simple; bh=+BpSywo2RlI8BW6DOlE1otMjRAQJkJig6+pDphhevfA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=SWWwhHfILBb5H0xx1oQvbXGiYDl7i3cu2VQZweT0ue1zMGSaizJQQRZd8JeJb5fSGRT+F1CKuqIhiM7x+IOn1DBVhwQPqhF6PDe7BUUMsuqXMEXk/3fvwiiasJQzVEivFfqUXnBAX1TLMfuiBbv2hH/+2OyoS64iZ+cXEoryBRM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Hvep/sNG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Hvep/sNG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38514C4CEEC; Tue, 18 Feb 2025 20:26:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739910419; bh=+BpSywo2RlI8BW6DOlE1otMjRAQJkJig6+pDphhevfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hvep/sNGRESIUqOcBxcaw4Yf42g8NewRR7QPA0ZxtkcGbgkFq3DlEgqy8e1i6cPw4 bvowu75A7pWKuCeHWJQvhzHdrtBTHUbIULMvI8C5HnL+xv/54nxiVnzfIMfxzcqLGb G9btS+iV31gMkZJhoW2/DUxtc3vj4UHl0tP714AtadATJ1x7FiAQI6ql/WrqPw7iJk y5yoVAgjYXGbv6lE4Jldd3B7Mf+TXelh2dNsBQ53P8LDvuGMrl9BK+iDp0vrSPEeKc PzyJa2L1S3duvVh2Ks/M93+JdQSSP7AHffSH3zeyGb33vzD9K266r4noCBytIwua2X J1vobllgcTYrw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Peter Oberparleiter , Vineeth Vijayan , Eric Farman , Vasily Gorbik , Sasha Levin , hca@linux.ibm.com, agordeev@linux.ibm.com, linux-s390@vger.kernel.org Subject: [PATCH AUTOSEL 6.12 19/31] s390/cio: Fix CHPID "configure" attribute caching Date: Tue, 18 Feb 2025 15:26:05 -0500 Message-Id: <20250218202619.3592630-19-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250218202619.3592630-1-sashal@kernel.org> References: <20250218202619.3592630-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.12.15 Content-Transfer-Encoding: 8bit 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 a07bbecba61cd..0c5bda060249e 100644 --- a/drivers/s390/cio/chp.c +++ b/drivers/s390/cio/chp.c @@ -682,7 +682,8 @@ 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