From 1b22cfb14142aba7742d307c4f8d7006f919308c Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Thu, 11 May 2023 03:13:42 +0200 Subject: [PATCH] scsi: core: Allow enabling and disabling command duration limits Add the sysfs scsi_device attribute cdl_enable to allow a user to enable or disable a device command duration limits feature. CDL is disabled by default. This feature must be explicitly enabled by a user by setting the cdl_enable attribute to 1. The new function scsi_cdl_enable() does not do anything beside setting the cdl_enable field of struct scsi_device in the case of a (real) SCSI device (e.g. a SAS HDD). For ATA devices, the command duration limits feature needs to be enabled/disabled using the ATA feature sub-page of the control mode page. To do so, the scsi_cdl_enable() function checks if this mode page is supported using scsi_mode_sense(). If it is, scsi_mode_select() is used to enable and disable CDL. Signed-off-by: Damien Le Moal Reviewed-by: Hannes Reinecke Co-developed-by: Niklas Cassel Signed-off-by: Niklas Cassel Link: https://lore.kernel.org/r/20230511011356.227789-10-nks@flawful.org Signed-off-by: Martin K. Petersen --- Documentation/ABI/testing/sysfs-block-device | 13 ++++++ drivers/scsi/scsi.c | 62 ++++++++++++++++++++++++++++ drivers/scsi/scsi_sysfs.c | 28 +++++++++++++ include/scsi/scsi_device.h | 2 + 4 files changed, 105 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-block-device b/Documentation/ABI/testing/sysfs-block-device index ffc3358..2d543cf 100644 --- a/Documentation/ABI/testing/sysfs-block-device +++ b/Documentation/ABI/testing/sysfs-block-device @@ -104,3 +104,16 @@ Contact: linux-scsi@vger.kernel.org Description: (RO) Indicates if the device supports the command duration limits feature found in some ATA and SCSI devices. + + +What: /sys/block/*/device/cdl_enable +Date: May, 2023 +KernelVersion: v6.5 +Contact: linux-scsi@vger.kernel.org +Description: + (RW) For a device supporting the command duration limits + feature, write to the file to turn on or off the feature. + By default this feature is turned off. + Writing "1" to this file enables the use of command duration + limits for read and write commands in the kernel and turns on + the feature on the device. Writing "0" disables the feature. diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index c03814c..c4bf99a 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -652,6 +652,68 @@ void scsi_cdl_check(struct scsi_device *sdev) } /** + * scsi_cdl_enable - Enable or disable a SCSI device supports for Command + * Duration Limits + * @sdev: The target device + * @enable: the target state + */ +int scsi_cdl_enable(struct scsi_device *sdev, bool enable) +{ + struct scsi_mode_data data; + struct scsi_sense_hdr sshdr; + struct scsi_vpd *vpd; + bool is_ata = false; + char buf[64]; + int ret; + + if (!sdev->cdl_supported) + return -EOPNOTSUPP; + + rcu_read_lock(); + vpd = rcu_dereference(sdev->vpd_pg89); + if (vpd) + is_ata = true; + rcu_read_unlock(); + + /* + * For ATA devices, CDL needs to be enabled with a SET FEATURES command. + */ + if (is_ata) { + char *buf_data; + int len; + + ret = scsi_mode_sense(sdev, 0x08, 0x0a, 0xf2, buf, sizeof(buf), + 5 * HZ, 3, &data, NULL); + if (ret) + return -EINVAL; + + /* Enable CDL using the ATA feature page */ + len = min_t(size_t, sizeof(buf), + data.length - data.header_length - + data.block_descriptor_length); + buf_data = buf + data.header_length + + data.block_descriptor_length; + if (enable) + buf_data[4] = 0x02; + else + buf_data[4] = 0; + + ret = scsi_mode_select(sdev, 1, 0, buf_data, len, 5 * HZ, 3, + &data, &sshdr); + if (ret) { + if (scsi_sense_valid(&sshdr)) + scsi_print_sense_hdr(sdev, + dev_name(&sdev->sdev_gendev), &sshdr); + return ret; + } + } + + sdev->cdl_enable = enable; + + return 0; +} + +/** * scsi_device_get - get an additional reference to a scsi_device * @sdev: device to get a reference to * diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 98fcbbf..6031767 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -1222,6 +1222,33 @@ static DEVICE_ATTR(queue_ramp_up_period, S_IRUGO | S_IWUSR, sdev_show_queue_ramp_up_period, sdev_store_queue_ramp_up_period); +static ssize_t sdev_show_cdl_enable(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct scsi_device *sdev = to_scsi_device(dev); + + return sysfs_emit(buf, "%d\n", (int)sdev->cdl_enable); +} + +static ssize_t sdev_store_cdl_enable(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + int ret; + bool v; + + if (kstrtobool(buf, &v)) + return -EINVAL; + + ret = scsi_cdl_enable(to_scsi_device(dev), v); + if (ret) + return ret; + + return count; +} +static DEVICE_ATTR(cdl_enable, S_IRUGO | S_IWUSR, + sdev_show_cdl_enable, sdev_store_cdl_enable); + static umode_t scsi_sdev_attr_is_visible(struct kobject *kobj, struct attribute *attr, int i) { @@ -1302,6 +1329,7 @@ static struct attribute *scsi_sdev_attrs[] = { #endif &dev_attr_queue_ramp_up_period.attr, &dev_attr_cdl_supported.attr, + &dev_attr_cdl_enable.attr, REF_EVT(media_change), REF_EVT(inquiry_change_reported), REF_EVT(capacity_change_reported), diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 6b8df9e..b2cdb07 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -219,6 +219,7 @@ struct scsi_device { unsigned no_vpd_size:1; /* No VPD size reported in header */ unsigned cdl_supported:1; /* Command duration limits supported */ + unsigned cdl_enable:1; /* Enable/disable Command duration limits */ unsigned int queue_stopped; /* request queue is quiesced */ bool offline_already; /* Device offline message logged */ @@ -367,6 +368,7 @@ extern void scsi_remove_device(struct scsi_device *); extern int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh); void scsi_attach_vpd(struct scsi_device *sdev); void scsi_cdl_check(struct scsi_device *sdev); +int scsi_cdl_enable(struct scsi_device *sdev, bool enable); extern struct scsi_device *scsi_device_from_queue(struct request_queue *q); extern int __must_check scsi_device_get(struct scsi_device *); -- 2.7.4