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 EC27223472A; Tue, 18 Feb 2025 20:29:22 +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=1739910563; cv=none; b=jBU6uvkl29ikNwRYW7YL/ozxBZ1BfiZzQXRxbRLmKz5I5RwQ1BjKU0NsEDrjyWXHzt7ZOG1IJdM2oGdkcJsXEZgoyUXQFe7FZWQ0g+DBxF93cl8TKYivuCoB2Zr0/GiTXzBWaBFGvwOUH3HujPti0Ezl61z7/AK/I+Zu7ibeV3E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739910563; c=relaxed/simple; bh=dmPRugDYWLomWeFIK7sg+U6WYeBFqFFsqpCpSW2sVdk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=SgMEBbyw3NHJViRlde+/oD6x8lqRJ1nrmeaa0axCszuF50ORJ2SbQVNWln3B/kBEZcf/ACrnfE/GUJuxSQe4o7AiYYinos4GrmBgkjoU1xignvrM42z3BJMSjcgBE01hWkIvqUvXJTihWbFj2z+5lEU8x+jeM361Tj2JDP6znrk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Cka1kJs1; 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="Cka1kJs1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 668A8C4CEE4; Tue, 18 Feb 2025 20:29:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739910562; bh=dmPRugDYWLomWeFIK7sg+U6WYeBFqFFsqpCpSW2sVdk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cka1kJs1BZblNpbZwt1sK9VkMWY7N86Cm7yshD7KEnsB4KAdirb+2IdZYbcJSLln0 JOIxXvklBaOQ8LagwKoYhjjc8CZNiI5ETpCEI5bmhPfET8pcYJ2YSIjOTY5l/EgrJN y15vf0iNkGSftlLpIgw8L6sPz7Vuio73L2gpIJre3vixZjALE0uabtSce21/kShHpn 6S7+InCjOv+tS46kier2GdyWZDt06PosPWz46lmNViXjC9f1d3a6KwR+r3DT3jh6dy IAyD19BawKzRW68czJ8iO2q6jnH6nYjkZFGBEFiDtKDFrCTfquCmiIvYus2UBo9vvY 2HjIHv2I3oC6w== 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 5.4 3/3] s390/cio: Fix CHPID "configure" attribute caching Date: Tue, 18 Feb 2025 15:29:13 -0500 Message-Id: <20250218202914.3594039-3-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250218202914.3594039-1-sashal@kernel.org> References: <20250218202914.3594039-1-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 5.4.290 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 1fd982b4d64bd..18b2fc50463ba 100644 --- a/drivers/s390/cio/chp.c +++ b/drivers/s390/cio/chp.c @@ -646,7 +646,8 @@ 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