From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752564AbeEPFvt (ORCPT ); Wed, 16 May 2018 01:51:49 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:53042 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752245AbeEPFvq (ORCPT ); Wed, 16 May 2018 01:51:46 -0400 From: Nayna Jain To: linux-integrity@vger.kernel.org Cc: zohar@linux.vnet.ibm.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, peterhuewe@gmx.de, jarkko.sakkinen@linux.intel.com, tpmdd@selhorst.net, jgunthorpe@obsidianresearch.com, patrickc@us.ibm.com, Nayna Jain Subject: [PATCH v4 0/2] tpm: improving granularity in poll sleep times Date: Wed, 16 May 2018 01:51:23 -0400 X-Mailer: git-send-email 2.13.3 X-TM-AS-GCONF: 00 x-cbid: 18051605-0044-0000-0000-00000552E910 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18051605-0045-0000-0000-0000289453BA Message-Id: <20180516055125.5685-1-nayna@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-16_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805160059 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The existing TPM polling code sleeps in each loop iteration for time in msecs ranging from 1 msecs to 5 msecs. However, many of the TPM commands complete much faster, resulting in unnecessary delays. This set of patches identifies such iterations and optimizes the sleep time. The first patch replaces TPM_POLL_SLEEP with TPM_TIMEOUT_POLL and moves it from tpm_tis_core.c to tpm.h as an enum with value 1 msecs. The second patch further reduces the TPM poll sleep time in get_burstcount() and wait_for_tpm_stat() in tpm_tis_core.c by calling usleep_range() directly. The change is only in the polling time, and the maximum timeout is still maintained the same. Thus, it should not affect the overall existing behavior. Changelog: v4: tpm: reduce poll sleep time in tpm_transmit() * added Reviewed-by, Tested-by and Ack-by tpm: reduce polling time to usecs for even finer granularity * included Jarkko's feedback * added Ack-by v3: tpm: reduce poll sleep time in tpm_transmit() * added testing platform information * updated patch description for more clarity on reasoning tpm: reduce polling time to usecs for even finer granularity * added testing platform information * added Jarkko's and Mimi's Reviewed-by v2: tpm: reduce poll sleep time in tpm_transmit() * merged previously defined two patches into this. * updated patch description as per Jarkko's feedback tpm: reduce polling time to usecs for even finer granularity * directly use usleep_range with finer granularity less than 1msec Nayna Jain (2): tpm: reduce poll sleep time in tpm_transmit() tpm: reduce polling time to usecs for even finer granularity drivers/char/tpm/tpm-interface.c | 2 +- drivers/char/tpm/tpm.h | 5 ++++- drivers/char/tpm/tpm_tis_core.c | 11 +++-------- 3 files changed, 8 insertions(+), 10 deletions(-) -- 2.13.3