From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtTrxgGDKcLkjJNCwvUp49PE2prE5oDbqhHpTSY3mywu9Tct3SGFILqRmCoWwNzj77GeHfX ARC-Seal: i=1; a=rsa-sha256; t=1521483777; cv=none; d=google.com; s=arc-20160816; b=wGl4JcJqrU9LSnYVvDfCD1EaAG0CyF30zLGBHmu9WeNQvOP66h+KxQx9B6XO8mUBPf cYKGlTUuMPLbXJJldePNSA/+aAfEnwuQLgvdsIC8owia3UAomgIObOgDaHnB7LWYDdhG +oe011ui63MnJPO6hrRLQ6dEVqG7KzKtFA26oA40MFFt7U4Yg0644Ws8+vzZLNtS2SRv lQC4Hi3kMDQFQNf6ad4Pes8EOoUDFytlhCpmd0h3x44/DpQ3sDYc78D7RF+EQL/KMkiW STzZyYkmgLcz8pC0+ovxSvIvBGkr0JQBKWxD0LuRBAjDt+EY/8QyGavc569CyjRoB7Hw 8mNA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=zcY1Vltpw7gzXqdP0G1pyGYUH13TMIFdeWtKvaR7Q0Y=; b=kT5/VaaMzKwVAYHRkT+d/o1Xz2MqpSYh9N4KYTBCwI1QyPy0QhiGZaKv/ERv3Df4CO JLHxsPvCMV+GE2xOPTqo7aXIUyE+lFjaCUjQhWECUyvMOPjwpLtRitc+/cSIckKvka05 YJz61xnF9baw/OW+iA8TLvqdZgglJcrcqIXFdbMuJ8WgV2ggtpbYFNEFiBVwHe7JmKAW +JhYJsbhyAKfcUaY8hwjIS2R0dOquJy/y7BfwKN0CMfBdpDt3IA1Y5rcMRtwjp4FOBgN lUkZi3SFVcxnohfBsumO1Nya6OR0aB7FXUgIwbp6aD2buFP8fiESWc8idRT20tvaABoC N3hA== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mauricio Faria de Oliveira , Dan Williams , Song Liu , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 4.9 114/241] scsi: ses: dont get power status of SES device slot on probe Date: Mon, 19 Mar 2018 19:06:19 +0100 Message-Id: <20180319180755.922534281@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180319180751.172155436@linuxfoundation.org> References: <20180319180751.172155436@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1595390823017346049?= X-GMAIL-MSGID: =?utf-8?q?1595391373359930413?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mauricio Faria de Oliveira [ Upstream commit 75106523f39751390b5789b36ee1d213b3af1945 ] The commit 08024885a2a3 ("ses: Add power_status to SES device slot") introduced the 'power_status' attribute to enclosure components and the associated callbacks. There are 2 callbacks available to get the power status of a device: 1) ses_get_power_status() for 'struct enclosure_component_callbacks' 2) get_component_power_status() for the sysfs device attribute (these are available for kernel-space and user-space, respectively.) However, despite both methods being available to get power status on demand, that commit also introduced a call to get power status in ses_enclosure_data_process(). This dramatically increased the total probe time for SCSI devices on larger configurations, because ses_enclosure_data_process() is called several times during the SCSI devices probe and loops over the component devices (but that is another problem, another patch). That results in a tremendous continuous hammering of SCSI Receive Diagnostics commands to the enclosure-services device, which does delay the total probe time for the SCSI devices __significantly__: Originally, ~34 minutes on a system attached to ~170 disks: [ 9214.490703] mpt3sas version 13.100.00.00 loaded ... [11256.580231] scsi 17:0:177:0: qdepth(16), tagged(1), simple(0), ordered(0), scsi_level(6), cmd_que(1) With this patch, it decreased to ~2.5 minutes -- a 13.6x faster [ 1002.992533] mpt3sas version 13.100.00.00 loaded ... [ 1151.978831] scsi 11:0:177:0: qdepth(16), tagged(1), simple(0), ordered(0), scsi_level(6), cmd_que(1) Back to the commit discussion.. on the ses_get_power_status() call introduced in ses_enclosure_data_process(): impact of removing it. That may possibly be in place to initialize the power status value on device probe. However, those 2 functions available to retrieve that value _do_ automatically refresh/update it. So the potential benefit would be a direct access of the 'power_status' field which does not use the callbacks... But the only reader of 'struct enclosure_component::power_status' is the get_component_power_status() callback for sysfs attribute, and it _does_ check for and call the .get_power_status callback, (which indeed is defined and implemented by that commit), so the power status value is, again, automatically updated. So, the remaining potential for a direct/non-callback access to the power_status attribute would be out-of-tree modules -- well, for those, if they are for whatever reason interested in values that are set during device probe and not up-to-date by the time they need it.. well, that would be curious. Well, to handle that more properly, set the initial power state value to '-1' (i.e., uninitialized) instead of '1' (power 'on'), and check for it in that callback which may do an direct access to the field value _if_ a callback function is not defined. Signed-off-by: Mauricio Faria de Oliveira Fixes: 08024885a2a3 ("ses: Add power_status to SES device slot") Reviewed-by: Dan Williams Reviewed-by: Song Liu Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/misc/enclosure.c | 7 ++++++- drivers/scsi/ses.c | 1 - 2 files changed, 6 insertions(+), 2 deletions(-) --- a/drivers/misc/enclosure.c +++ b/drivers/misc/enclosure.c @@ -148,7 +148,7 @@ enclosure_register(struct device *dev, c for (i = 0; i < components; i++) { edev->component[i].number = -1; edev->component[i].slot = -1; - edev->component[i].power_status = 1; + edev->component[i].power_status = -1; } mutex_lock(&container_list_lock); @@ -600,6 +600,11 @@ static ssize_t get_component_power_statu if (edev->cb->get_power_status) edev->cb->get_power_status(edev, ecomp); + + /* If still uninitialized, the callback failed or does not exist. */ + if (ecomp->power_status == -1) + return (edev->cb->get_power_status) ? -EIO : -ENOTTY; + return snprintf(buf, 40, "%s\n", ecomp->power_status ? "on" : "off"); } --- a/drivers/scsi/ses.c +++ b/drivers/scsi/ses.c @@ -548,7 +548,6 @@ static void ses_enclosure_data_process(s ecomp = &edev->component[components++]; if (!IS_ERR(ecomp)) { - ses_get_power_status(edev, ecomp); if (addl_desc_ptr) ses_process_descriptor( ecomp,