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@wdc.com>
Link: https://lore.kernel.org/r/20241124070808.194860-4-avri.altman@wdc.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 939030672c8424a50c44e0111eb5d4ff29673eb7..9288575f94a2abdea88375848c2f3e57031120df 100644 (file)
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1816,19 +1816,16 @@ 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);
 
@@ -1863,7 +1860,7 @@ 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:
@@ -1879,11 +1876,11 @@ start:
                 */
                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;
@@ -1912,17 +1909,17 @@ start:
                 */
                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);
 
@@ -1930,30 +1927,32 @@ 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 ||
-           hba->clk_gating.active_reqs)
-               goto rel_lock;
+               if (hba->clk_gating.active_reqs)
+                       return;
+       }
 
-       spin_unlock_irqrestore(hba->host->host_lock, flags);
+       scoped_guard(spinlock_irqsave, hba->host->host_lock) {
+               if (ufshcd_is_ufs_dev_busy(hba) ||
+                   hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL)
+                       return;
+       }
 
        /* put the link into hibern8 mode before turning off clocks */
        if (ufshcd_can_hibern8_during_gating(hba)) {
@@ -1964,7 +1963,7 @@ 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);
        }
@@ -1984,32 +1983,34 @@ 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 */
 static void __ufshcd_release(struct ufs_hba *hba)
 {
+       lockdep_assert_held(&hba->clk_gating.lock);
+
        if (!ufshcd_is_clkgating_allowed(hba))
                return;
 
        hba->clk_gating.active_reqs--;
 
        if (hba->clk_gating.active_reqs || hba->clk_gating.is_suspended ||
-           hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL ||
-           ufshcd_has_pending_tasks(hba) || !hba->clk_gating.is_initialized ||
+           !hba->clk_gating.is_initialized ||
            hba->clk_gating.state == CLKS_OFF)
                return;
 
+       scoped_guard(spinlock_irqsave, hba->host->host_lock) {
+               if (ufshcd_has_pending_tasks(hba) ||
+                   hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL)
+                       return;
+       }
+
        hba->clk_gating.state = REQ_CLKS_OFF;
        trace_ufshcd_clk_gating(dev_name(hba->dev), hba->clk_gating.state);
        queue_delayed_work(hba->clk_gating.clk_gating_workq,
@@ -2019,11 +2020,8 @@ 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);
 
@@ -2038,11 +2036,9 @@ 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);
 
@@ -2070,7 +2066,6 @@ 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))
@@ -2078,9 +2073,10 @@ 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);
@@ -2088,8 +2084,7 @@ 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;
 }
 
@@ -2131,6 +2126,8 @@ 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);
@@ -9126,7 +9123,6 @@ 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;
 
@@ -9177,11 +9173,10 @@ out:
                                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 d7aca9e61684f9208f58126ff5c85b2934028361..b6311069d901aeb9ff5d7048f82557c549636490 100644 (file)
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -403,6 +403,9 @@ 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. An outer lock
+ * relative to the host lock
  * @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 +416,14 @@ 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 +432,6 @@ struct ufs_clk_gating {
        bool is_enabled;
        bool is_initialized;
        int active_reqs;
-       struct workqueue_struct *clk_gating_workq;
 };
 
 /**