Re: [PATCH v9 16/17] scsi: ufs: Forbid auto-hibernation without I/O scheduler

Bao D. Nguyen
2023-08-17T18:52:09Z

On 8/16/2023 12:53 PM, Bart Van Assche wrote:
> UFSHCI 3.0 controllers do not preserve the write order if auto-hibernation
> is enabled. If the write order is not preserved, an I/O scheduler is
> required to serialize zoned writes. Hence do not allow auto-hibernation
> to be enabled without I/O scheduler if a zoned logical unit is present
> and if the controller is operating in legacy mode. This patch has been
> tested with the following shell script:
>
> show_ah8() {
> echo -n "auto_hibern8: "
> adb shell "cat /sys/devices/platform/13200000.ufs/auto_hibern8"
> }
>
> set_ah8() {
> local rc
> adb shell "echo $1 > /sys/devices/platform/13200000.ufs/auto_hibern8"
> rc=$?
> show_ah8
> return $rc
> }
>
> set_iosched() {
> adb shell "echo $1 >/sys/class/block/$zoned_bdev/queue/scheduler &&
> echo -n 'I/O scheduler: ' &&
> cat /sys/class/block/sde/queue/scheduler"
> }
>
> adb root
> zoned_bdev=$(adb shell grep -lvw 0 /sys/class/block/sd*/queue/chunk_sectors |&
> sed 's|/sys/class/block/||g;s|/queue/chunk_sectors||g')
> [ -n "$zoned_bdev" ]
> show_ah8
> set_ah8 0
> set_iosched none
> if set_ah8 150000; then
> echo "Error: enabled AH8 without I/O scheduler"
> fi
> set_iosched mq-deadline
> set_ah8 150000
>
> Cc: Martin K. Petersen <martin.petersen@oracle.com>
> Cc: Can Guo <quic_cang@quicinc.com>
> Cc: Avri Altman <avri.altman@wdc.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Damien Le Moal <dlemoal@kernel.org>
> Cc: Ming Lei <ming.lei@redhat.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
> drivers/ufs/core/ufs-sysfs.c | 2 +-
> drivers/ufs/core/ufshcd-priv.h | 1 -
> drivers/ufs/core/ufshcd.c | 60 ++++++++++++++++++++++++++++++++--
> include/ufs/ufshcd.h | 2 +-
> 4 files changed, 60 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
> index 6c72075750dd..a693dea1bd18 100644
> --- a/drivers/ufs/core/ufs-sysfs.c
> +++ b/drivers/ufs/core/ufs-sysfs.c
> @@ -203,7 +203,7 @@ static ssize_t auto_hibern8_store(struct device *dev,
> goto out;
> }
>
> - ufshcd_auto_hibern8_update(hba, ufshcd_us_to_ahit(timer));
> + ret = ufshcd_auto_hibern8_update(hba, ufshcd_us_to_ahit(timer));
>
> out:
> up(&hba->host_sem);
> diff --git a/drivers/ufs/core/ufshcd-priv.h b/drivers/ufs/core/ufshcd-priv.h
> index 0f3bd943b58b..a2b74fbc2056 100644
> --- a/drivers/ufs/core/ufshcd-priv.h
> +++ b/drivers/ufs/core/ufshcd-priv.h
> @@ -60,7 +60,6 @@ int ufshcd_query_attr(struct ufs_hba *hba, enum query_opcode opcode,
> enum attr_idn idn, u8 index, u8 selector, u32 *attr_val);
> int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
> enum flag_idn idn, u8 index, bool *flag_res);
> -void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit);
> void ufshcd_compl_one_cqe(struct ufs_hba *hba, int task_tag,
> struct cq_entry *cqe);
> int ufshcd_mcq_init(struct ufs_hba *hba);
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 39000c018d8b..37d430d20939 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -4337,6 +4337,29 @@ int ufshcd_uic_hibern8_exit(struct ufs_hba *hba)
> }
> EXPORT_SYMBOL_GPL(ufshcd_uic_hibern8_exit);
>
> +static int ufshcd_update_preserves_write_order(struct ufs_hba *hba,
> + bool preserves_write_order)
> +{
> + struct scsi_device *sdev;
> +
> + if (!preserves_write_order) {
> + shost_for_each_device(sdev, hba->host) {
> + struct request_queue *q = sdev->request_queue;
> +
> + /*
> + * This code does not check whether the attached I/O
> + * scheduler serializes zoned writes
> + * (ELEVATOR_F_ZBD_SEQ_WRITE) because this cannot be
> + * checked from outside the block layer core.
> + */
> + if (blk_queue_is_zoned(q) && !q->elevator)
> + return -EPERM;
> + }
> + }
> +
> + return 0;
> +}
> +
> static void ufshcd_configure_auto_hibern8(struct ufs_hba *hba)
> {
> if (!ufshcd_is_auto_hibern8_supported(hba))
> @@ -4345,13 +4368,37 @@ static void ufshcd_configure_auto_hibern8(struct ufs_hba *hba)
> ufshcd_writel(hba, hba->ahit, REG_AUTO_HIBERNATE_IDLE_TIMER);
> }
>
> -void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit)
> +/**
> + * ufshcd_auto_hibern8_update() - Modify the auto-hibernation control register
> + * @hba: per-adapter instance
> + * @ahit: New auto-hibernate settings. Includes the scale and the value of the
> + * auto-hibernation timer. See also the UFSHCI_AHIBERN8_TIMER_MASK and
> + * UFSHCI_AHIBERN8_SCALE_MASK constants.
> + *
> + * Note: enabling auto-hibernation if a zoned logical unit is present without
> + * attaching the mq-deadline scheduler first to the zoned logical unit may cause
> + * unaligned write errors for the zoned logical unit.
> + */
Please improve this "Note:". It seems like a run-on sentence and not
very clear.

> +int ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit)
> {
> const u32 cur_ahit = READ_ONCE(hba->ahit);
> + bool prev_state, new_state;
> + int ret;
>
> if (!ufshcd_is_auto_hibern8_supported(hba) || cur_ahit == ahit)
> - return;
> + return 0;
>
> + prev_state = FIELD_GET(UFSHCI_AHIBERN8_TIMER_MASK, cur_ahit);
> + new_state = FIELD_GET(UFSHCI_AHIBERN8_TIMER_MASK, ahit);
> +
> + if (!is_mcq_enabled(hba) && !prev_state && new_state) {
> + /*
> + * Auto-hibernation will be enabled for legacy UFSHCI mode.
> + */
> + ret = ufshcd_update_preserves_write_order(hba, false);
> + if (ret)
> + return ret;
> + }
> WRITE_ONCE(hba->ahit, ahit);
> if (!pm_runtime_suspended(&hba->ufs_device_wlun->sdev_gendev)) {
> ufshcd_rpm_get_sync(hba);
> @@ -4360,6 +4407,15 @@ void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit)
> ufshcd_release(hba);
> ufshcd_rpm_put_sync(hba);
> }
> + if (!is_mcq_enabled(hba) && prev_state && !new_state) {
> + /*
> + * Auto-hibernation has been disabled.
> + */
> + ret = ufshcd_update_preserves_write_order(hba, true);
> + WARN_ON_ONCE(ret);
> + }
> +
> + return 0;
> }
> EXPORT_SYMBOL_GPL(ufshcd_auto_hibern8_update);
>
> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> index 040d66d99912..7ae071a6811c 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -1363,7 +1363,7 @@ static inline int ufshcd_disable_host_tx_lcc(struct ufs_hba *hba)
> return ufshcd_dme_set(hba, UIC_ARG_MIB(PA_LOCAL_TX_LCC_ENABLE), 0);
> }
>
> -void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit);
> +int ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit);
> void ufshcd_fixup_dev_quirks(struct ufs_hba *hba,
> const struct ufs_dev_quirk *fixups);
> #define SD_ASCII_STD true