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Message-ID:
<DM6PR04MB6575F8FA15D71505DFE39FFDFC5E2@DM6PR04MB6575.namprd04.prod.outlook.com>
Date: Sat, 9 Nov 2024 06:05:44 +0000
From: Avri Altman <Avri.Altman@....com>
To: "Martin K . Petersen" <martin.petersen@...cle.com>
CC: "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Bart Van
Assche <bvanassche@....org>
Subject: RE: [PATCH v3 1/2] scsi: ufs: core: Introduce a new clock_gating lock
A gentle ping.
Thanks,
Avri
> -----Original Message-----
> From: Avri Altman <avri.altman@....com>
> Sent: Tuesday, November 5, 2024 1:25 PM
> To: Martin K . Petersen <martin.petersen@...cle.com>
> Cc: linux-scsi@...r.kernel.org; linux-kernel@...r.kernel.org; Bart Van Assche
> <bvanassche@....org>; Avri Altman <Avri.Altman@....com>
> Subject: [PATCH v3 1/2] scsi: ufs: core: Introduce a new clock_gating lock
>
> Introduce a new clock gating lock to serialize access to some of the clock gating
> members instead of the host_lock.
>
> While at it, simplify the code with the guard() macro and co for automatic
> cleanup of the new lock. There are some explicit
> spin_lock_irqsave/spin_unlock_irqrestore snaking instances I left behind
> because I couldn't make heads or tails of it.
>
> Additionally, move the trace_ufshcd_clk_gating() call from inside the region
> protected by the lock as it doesn't needs protection.
>
> Signed-off-by: Avri Altman <avri.altman@....com>
> ---
> drivers/ufs/core/ufshcd.c | 93 +++++++++++++++++----------------------
> include/ufs/ufshcd.h | 8 +++-
> 2 files changed, 46 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index
> e338867bc96c..62c0e2323f50 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -1811,19 +1811,17 @@ static void ufshcd_exit_clk_scaling(struct ufs_hba
> *hba) static void ufshcd_ungate_work(struct work_struct *work) {
> int ret;
> - unsigned long flags;
> struct ufs_hba *hba = container_of(work, struct ufs_hba,
> clk_gating.ungate_work);
>
> cancel_delayed_work_sync(&hba->clk_gating.gate_work);
>
> - spin_lock_irqsave(hba->host->host_lock, flags);
> - if (hba->clk_gating.state == CLKS_ON) {
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> - return;
> + scoped_guard(spinlock_irqsave, &hba->clk_gating.lock)
> + {
> + if (hba->clk_gating.state == CLKS_ON)
> + return;
> }
>
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> ufshcd_hba_vreg_set_hpm(hba);
> ufshcd_setup_clocks(hba, true);
>
> @@ -1858,7 +1856,7 @@ void ufshcd_hold(struct ufs_hba *hba)
> if (!ufshcd_is_clkgating_allowed(hba) ||
> !hba->clk_gating.is_initialized)
> return;
> - spin_lock_irqsave(hba->host->host_lock, flags);
> + spin_lock_irqsave(&hba->clk_gating.lock, flags);
> hba->clk_gating.active_reqs++;
>
> start:
> @@ -1874,11 +1872,11 @@ void ufshcd_hold(struct ufs_hba *hba)
> */
> if (ufshcd_can_hibern8_during_gating(hba) &&
> ufshcd_is_link_hibern8(hba)) {
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> + spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> flush_result = flush_work(&hba-
> >clk_gating.ungate_work);
> if (hba->clk_gating.is_suspended && !flush_result)
> return;
> - spin_lock_irqsave(hba->host->host_lock, flags);
> + spin_lock_irqsave(&hba->clk_gating.lock, flags);
> goto start;
> }
> break;
> @@ -1907,17 +1905,17 @@ void ufshcd_hold(struct ufs_hba *hba)
> */
> fallthrough;
> case REQ_CLKS_ON:
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> + spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> flush_work(&hba->clk_gating.ungate_work);
> /* Make sure state is CLKS_ON before returning */
> - spin_lock_irqsave(hba->host->host_lock, flags);
> + spin_lock_irqsave(&hba->clk_gating.lock, flags);
> goto start;
> default:
> dev_err(hba->dev, "%s: clk gating is in invalid state %d\n",
> __func__, hba->clk_gating.state);
> break;
> }
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> + spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> }
> EXPORT_SYMBOL_GPL(ufshcd_hold);
>
> @@ -1925,29 +1923,28 @@ static void ufshcd_gate_work(struct work_struct
> *work) {
> struct ufs_hba *hba = container_of(work, struct ufs_hba,
> clk_gating.gate_work.work);
> - unsigned long flags;
> int ret;
>
> - spin_lock_irqsave(hba->host->host_lock, flags);
> - /*
> - * In case you are here to cancel this work the gating state
> - * would be marked as REQ_CLKS_ON. In this case save time by
> - * skipping the gating work and exit after changing the clock
> - * state to CLKS_ON.
> - */
> - if (hba->clk_gating.is_suspended ||
> - (hba->clk_gating.state != REQ_CLKS_OFF)) {
> - hba->clk_gating.state = CLKS_ON;
> - trace_ufshcd_clk_gating(dev_name(hba->dev),
> - hba->clk_gating.state);
> - goto rel_lock;
> + scoped_guard(spinlock_irqsave, &hba->clk_gating.lock)
> + {
> + /*
> + * In case you are here to cancel this work the gating state
> + * would be marked as REQ_CLKS_ON. In this case save time by
> + * skipping the gating work and exit after changing the clock
> + * state to CLKS_ON.
> + */
> + if (hba->clk_gating.is_suspended ||
> + hba->clk_gating.state != REQ_CLKS_OFF) {
> + hba->clk_gating.state = CLKS_ON;
> + trace_ufshcd_clk_gating(dev_name(hba->dev),
> + hba->clk_gating.state);
> + return;
> + }
> + if (ufshcd_is_ufs_dev_busy(hba) ||
> + hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL)
> + return;
> }
>
> - if (ufshcd_is_ufs_dev_busy(hba) || hba->ufshcd_state !=
> UFSHCD_STATE_OPERATIONAL)
> - goto rel_lock;
> -
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> -
> /* put the link into hibern8 mode before turning off clocks */
> if (ufshcd_can_hibern8_during_gating(hba)) {
> ret = ufshcd_uic_hibern8_enter(hba);
> @@ -1957,7 +1954,7 @@ static void ufshcd_gate_work(struct work_struct
> *work)
> __func__, ret);
> trace_ufshcd_clk_gating(dev_name(hba->dev),
> hba->clk_gating.state);
> - goto out;
> + return;
> }
> ufshcd_set_link_hibern8(hba);
> }
> @@ -1977,16 +1974,12 @@ static void ufshcd_gate_work(struct work_struct
> *work)
> * prevent from doing cancel work multiple times when there are
> * new requests arriving before the current cancel work is done.
> */
> - spin_lock_irqsave(hba->host->host_lock, flags);
> + guard(spinlock_irqsave)(&hba->clk_gating.lock);
> if (hba->clk_gating.state == REQ_CLKS_OFF) {
> hba->clk_gating.state = CLKS_OFF;
> trace_ufshcd_clk_gating(dev_name(hba->dev),
> hba->clk_gating.state);
> }
> -rel_lock:
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> -out:
> - return;
> }
>
> /* host lock must be held before calling this variant */ @@ -2013,11 +2006,8
> @@ static void __ufshcd_release(struct ufs_hba *hba)
>
> void ufshcd_release(struct ufs_hba *hba) {
> - unsigned long flags;
> -
> - spin_lock_irqsave(hba->host->host_lock, flags);
> + guard(spinlock_irqsave)(&hba->clk_gating.lock);
> __ufshcd_release(hba);
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> }
> EXPORT_SYMBOL_GPL(ufshcd_release);
>
> @@ -2032,11 +2022,9 @@ static ssize_t ufshcd_clkgate_delay_show(struct
> device *dev, void ufshcd_clkgate_delay_set(struct device *dev, unsigned long
> value) {
> struct ufs_hba *hba = dev_get_drvdata(dev);
> - unsigned long flags;
>
> - spin_lock_irqsave(hba->host->host_lock, flags);
> + guard(spinlock_irqsave)(&hba->clk_gating.lock);
> hba->clk_gating.delay_ms = value;
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> }
> EXPORT_SYMBOL_GPL(ufshcd_clkgate_delay_set);
>
> @@ -2064,7 +2052,6 @@ static ssize_t ufshcd_clkgate_enable_store(struct
> device *dev,
> struct device_attribute *attr, const char *buf, size_t count) {
> struct ufs_hba *hba = dev_get_drvdata(dev);
> - unsigned long flags;
> u32 value;
>
> if (kstrtou32(buf, 0, &value))
> @@ -2072,9 +2059,10 @@ static ssize_t ufshcd_clkgate_enable_store(struct
> device *dev,
>
> value = !!value;
>
> - spin_lock_irqsave(hba->host->host_lock, flags);
> + guard(spinlock_irqsave)(&hba->clk_gating.lock);
> +
> if (value == hba->clk_gating.is_enabled)
> - goto out;
> + return count;
>
> if (value)
> __ufshcd_release(hba);
> @@ -2082,8 +2070,7 @@ static ssize_t ufshcd_clkgate_enable_store(struct
> device *dev,
> hba->clk_gating.active_reqs++;
>
> hba->clk_gating.is_enabled = value;
> -out:
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> +
> return count;
> }
>
> @@ -2125,6 +2112,8 @@ static void ufshcd_init_clk_gating(struct ufs_hba
> *hba)
> INIT_DELAYED_WORK(&hba->clk_gating.gate_work,
> ufshcd_gate_work);
> INIT_WORK(&hba->clk_gating.ungate_work, ufshcd_ungate_work);
>
> + spin_lock_init(&hba->clk_gating.lock);
> +
> hba->clk_gating.clk_gating_workq = alloc_ordered_workqueue(
> "ufs_clk_gating_%d", WQ_MEM_RECLAIM | WQ_HIGHPRI,
> hba->host->host_no);
> @@ -9112,7 +9101,6 @@ static int ufshcd_setup_clocks(struct ufs_hba *hba,
> bool on)
> int ret = 0;
> struct ufs_clk_info *clki;
> struct list_head *head = &hba->clk_list_head;
> - unsigned long flags;
> ktime_t start = ktime_get();
> bool clk_state_changed = false;
>
> @@ -9163,11 +9151,10 @@ static int ufshcd_setup_clocks(struct ufs_hba *hba,
> bool on)
> clk_disable_unprepare(clki->clk);
> }
> } else if (!ret && on) {
> - spin_lock_irqsave(hba->host->host_lock, flags);
> - hba->clk_gating.state = CLKS_ON;
> + scoped_guard(spinlock_irqsave, &hba->clk_gating.lock)
> + hba->clk_gating.state = CLKS_ON;
> trace_ufshcd_clk_gating(dev_name(hba->dev),
> hba->clk_gating.state);
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> }
>
> if (clk_state_changed)
> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h index
> d7aca9e61684..8f9997b0dbf9 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -403,6 +403,8 @@ enum clk_gating_state {
> * delay_ms
> * @ungate_work: worker to turn on clocks that will be used in case of
> * interrupt context
> + * @clk_gating_workq: workqueue for clock gating work.
> + * @lock: serialize access to some struct ufs_clk_gating members
> * @state: the current clocks state
> * @delay_ms: gating delay in ms
> * @is_suspended: clk gating is suspended when set to 1 which can be used
> @@ -413,11 +415,14 @@ enum clk_gating_state {
> * @is_initialized: Indicates whether clock gating is initialized or not
> * @active_reqs: number of requests that are pending and should be waited for
> * completion before gating clocks.
> - * @clk_gating_workq: workqueue for clock gating work.
> */
> struct ufs_clk_gating {
> struct delayed_work gate_work;
> struct work_struct ungate_work;
> + struct workqueue_struct *clk_gating_workq;
> +
> + spinlock_t lock;
> +
> enum clk_gating_state state;
> unsigned long delay_ms;
> bool is_suspended;
> @@ -426,7 +431,6 @@ struct ufs_clk_gating {
> bool is_enabled;
> bool is_initialized;
> int active_reqs;
> - struct workqueue_struct *clk_gating_workq;
> };
>
> /**
> --
> 2.25.1
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