coresight: cti: Make spinlock usage consistent

The spinlock is acquired sometimes with IRQs disabled and sometimes
without.  This leads to inconsistent semantics: the lock can be either
HARDIRQ-safe or HARDIRQ-unsafe, which may trigger lockdep complaints.

Make spinlock usage consistent by acquiring it with disabling IRQs.  It
is possible for sysfs knobs to acquire the spinlock for accessing a
CTI device, while at the same time a perf session sends an IPI to
enable the same CTI device.  In this case, the spinlock must be
IRQ-safe, which is why all lock acquisitions are changed to disable
IRQs.

Use guard() and scoped_guard() for spinlock to tidy up the code.

Fixes: 984f37efa385 ("coresight: cti: Write regsiters directly in cti_enable_hw()")
Tested-by: James Clark <james.clark@linaro.org>
Reviewed-by: Mike Leach <mike.leach@arm.com>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20260226-arm_coresight_cti_refactor_v1-v2-1-b30fada3cfec@arm.com

diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c
index fddc8f31b91dccba1506aae8c2fd5f348240b98b..e3c98d89c987c10faafa02d1dbd721cfd4187edb 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-cti-core.c
+++ b/drivers/hwtracing/coresight/coresight-cti-core.c
@@ -81,10 +81,9 @@ void cti_write_all_hw_regs(struct cti_drvdata *drvdata)
 static int cti_enable_hw(struct cti_drvdata *drvdata)
 {
        struct cti_config *config = &drvdata->config;
-       unsigned long flags;
-       int rc = 0;
+       int rc;
 
-       raw_spin_lock_irqsave(&drvdata->spinlock, flags);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
 
        /* no need to do anything if enabled or unpowered*/
        if (config->hw_enabled || !config->hw_powered)
@@ -93,22 +92,15 @@ static int cti_enable_hw(struct cti_drvdata *drvdata)
        /* claim the device */
        rc = coresight_claim_device(drvdata->csdev);
        if (rc)
-               goto cti_err_not_enabled;
+               return rc;
 
        cti_write_all_hw_regs(drvdata);
 
        config->hw_enabled = true;
-       drvdata->config.enable_req_count++;
-       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
-       return rc;
 
 cti_state_unchanged:
        drvdata->config.enable_req_count++;
-
-       /* cannot enable due to error */
-cti_err_not_enabled:
-       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
-       return rc;
+       return 0;
 }
 
 /* re-enable CTI on CPU when using CPU hotplug */
@@ -116,25 +108,21 @@ static void cti_cpuhp_enable_hw(struct cti_drvdata *drvdata)
 {
        struct cti_config *config = &drvdata->config;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        config->hw_powered = true;
 
        /* no need to do anything if no enable request */
        if (!drvdata->config.enable_req_count)
-               goto cti_hp_not_enabled;
+               return;
 
        /* try to claim the device */
        if (coresight_claim_device(drvdata->csdev))
-               goto cti_hp_not_enabled;
+               return;
 
        cti_write_all_hw_regs(drvdata);
        config->hw_enabled = true;
-       raw_spin_unlock(&drvdata->spinlock);
        return;
-
-       /* did not re-enable due to no claim / no request */
-cti_hp_not_enabled:
-       raw_spin_unlock(&drvdata->spinlock);
 }
 
 /* disable hardware */
@@ -142,23 +130,20 @@ static int cti_disable_hw(struct cti_drvdata *drvdata)
 {
        struct cti_config *config = &drvdata->config;
        struct coresight_device *csdev = drvdata->csdev;
-       int ret = 0;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
 
        /* don't allow negative refcounts, return an error */
-       if (!drvdata->config.enable_req_count) {
-               ret = -EINVAL;
-               goto cti_not_disabled;
-       }
+       if (!drvdata->config.enable_req_count)
+               return -EINVAL;
 
        /* check refcount - disable on 0 */
        if (--drvdata->config.enable_req_count > 0)
-               goto cti_not_disabled;
+               return 0;
 
        /* no need to do anything if disabled or cpu unpowered */
        if (!config->hw_enabled || !config->hw_powered)
-               goto cti_not_disabled;
+               return 0;
 
        CS_UNLOCK(drvdata->base);
 
@@ -168,13 +153,7 @@ static int cti_disable_hw(struct cti_drvdata *drvdata)
 
        coresight_disclaim_device_unlocked(csdev);
        CS_LOCK(drvdata->base);
-       raw_spin_unlock(&drvdata->spinlock);
-       return ret;
-
-       /* not disabled this call */
-cti_not_disabled:
-       raw_spin_unlock(&drvdata->spinlock);
-       return ret;
+       return 0;
 }
 
 void cti_write_single_reg(struct cti_drvdata *drvdata, int offset, u32 value)
@@ -189,11 +168,11 @@ void cti_write_intack(struct device *dev, u32 ackval)
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
        struct cti_config *config = &drvdata->config;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        /* write if enabled */
        if (cti_active(config))
                cti_write_single_reg(drvdata, CTIINTACK, ackval);
-       raw_spin_unlock(&drvdata->spinlock);
 }
 
 /*
@@ -360,7 +339,7 @@ int cti_channel_trig_op(struct device *dev, enum cti_chan_op op,
        reg_offset = (direction == CTI_TRIG_IN ? CTIINEN(trigger_idx) :
                      CTIOUTEN(trigger_idx));
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
 
        /* read - modify write - the trigger / channel enable value */
        reg_value = direction == CTI_TRIG_IN ? config->ctiinen[trigger_idx] :
@@ -379,7 +358,7 @@ int cti_channel_trig_op(struct device *dev, enum cti_chan_op op,
        /* write through if enabled */
        if (cti_active(config))
                cti_write_single_reg(drvdata, reg_offset, reg_value);
-       raw_spin_unlock(&drvdata->spinlock);
+
        return 0;
 }
 
@@ -397,7 +376,8 @@ int cti_channel_gate_op(struct device *dev, enum cti_chan_gate_op op,
 
        chan_bitmask = BIT(channel_idx);
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        reg_value = config->ctigate;
        switch (op) {
        case CTI_GATE_CHAN_ENABLE:
@@ -417,7 +397,7 @@ int cti_channel_gate_op(struct device *dev, enum cti_chan_gate_op op,
                if (cti_active(config))
                        cti_write_single_reg(drvdata, CTIGATE, reg_value);
        }
-       raw_spin_unlock(&drvdata->spinlock);
+
        return err;
 }
 
@@ -436,7 +416,8 @@ int cti_channel_setop(struct device *dev, enum cti_chan_set_op op,
 
        chan_bitmask = BIT(channel_idx);
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        reg_value = config->ctiappset;
        switch (op) {
        case CTI_CHAN_SET:
@@ -464,7 +445,6 @@ int cti_channel_setop(struct device *dev, enum cti_chan_set_op op,
 
        if ((err == 0) && cti_active(config))
                cti_write_single_reg(drvdata, reg_offset, reg_value);
-       raw_spin_unlock(&drvdata->spinlock);
 
        return err;
 }
@@ -667,7 +647,7 @@ static int cti_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
        if (WARN_ON_ONCE(drvdata->ctidev.cpu != cpu))
                return NOTIFY_BAD;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
 
        switch (cmd) {
        case CPU_PM_ENTER:
@@ -707,7 +687,6 @@ static int cti_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
        }
 
 cti_notify_exit:
-       raw_spin_unlock(&drvdata->spinlock);
        return notify_res;
 }
 
@@ -734,11 +713,12 @@ static int cti_dying_cpu(unsigned int cpu)
        if (!drvdata)
                return 0;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        drvdata->config.hw_powered = false;
        if (drvdata->config.hw_enabled)
                coresight_disclaim_device(drvdata->csdev);
-       raw_spin_unlock(&drvdata->spinlock);
+
        return 0;
 }
 

diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
index 572b80ee96fbf18ec8cf9abc30d109a676dfbc5d..455d08bcccd49a3f1eac8abd8246806ef73a9ab6 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
@@ -84,11 +84,11 @@ static ssize_t enable_show(struct device *dev,
        bool enabled, powered;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
 
-       raw_spin_lock(&drvdata->spinlock);
-       enable_req = drvdata->config.enable_req_count;
-       powered = drvdata->config.hw_powered;
-       enabled = drvdata->config.hw_enabled;
-       raw_spin_unlock(&drvdata->spinlock);
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               enable_req = drvdata->config.enable_req_count;
+               powered = drvdata->config.hw_powered;
+               enabled = drvdata->config.hw_enabled;
+       }
 
        if (powered)
                return sprintf(buf, "%d\n", enabled);
@@ -134,9 +134,8 @@ static ssize_t powered_show(struct device *dev,
        bool powered;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
 
-       raw_spin_lock(&drvdata->spinlock);
-       powered = drvdata->config.hw_powered;
-       raw_spin_unlock(&drvdata->spinlock);
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock)
+               powered = drvdata->config.hw_powered;
 
        return sprintf(buf, "%d\n", powered);
 }
@@ -181,10 +180,12 @@ static ssize_t coresight_cti_reg_show(struct device *dev,
        u32 val = 0;
 
        pm_runtime_get_sync(dev->parent);
-       raw_spin_lock(&drvdata->spinlock);
-       if (drvdata->config.hw_powered)
-               val = readl_relaxed(drvdata->base + cti_attr->off);
-       raw_spin_unlock(&drvdata->spinlock);
+
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               if (drvdata->config.hw_powered)
+                       val = readl_relaxed(drvdata->base + cti_attr->off);
+       }
+
        pm_runtime_put_sync(dev->parent);
        return sysfs_emit(buf, "0x%x\n", val);
 }
@@ -202,10 +203,12 @@ static __maybe_unused ssize_t coresight_cti_reg_store(struct device *dev,
                return -EINVAL;
 
        pm_runtime_get_sync(dev->parent);
-       raw_spin_lock(&drvdata->spinlock);
-       if (drvdata->config.hw_powered)
-               cti_write_single_reg(drvdata, cti_attr->off, val);
-       raw_spin_unlock(&drvdata->spinlock);
+
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               if (drvdata->config.hw_powered)
+                       cti_write_single_reg(drvdata, cti_attr->off, val);
+       }
+
        pm_runtime_put_sync(dev->parent);
        return size;
 }
@@ -264,17 +267,18 @@ static ssize_t cti_reg32_show(struct device *dev, char *buf,
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
        struct cti_config *config = &drvdata->config;
 
-       raw_spin_lock(&drvdata->spinlock);
-       if ((reg_offset >= 0) && cti_active(config)) {
-               CS_UNLOCK(drvdata->base);
-               val = readl_relaxed(drvdata->base + reg_offset);
-               if (pcached_val)
-                       *pcached_val = val;
-               CS_LOCK(drvdata->base);
-       } else if (pcached_val) {
-               val = *pcached_val;
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               if ((reg_offset >= 0) && cti_active(config)) {
+                       CS_UNLOCK(drvdata->base);
+                       val = readl_relaxed(drvdata->base + reg_offset);
+                       if (pcached_val)
+                               *pcached_val = val;
+                       CS_LOCK(drvdata->base);
+               } else if (pcached_val) {
+                       val = *pcached_val;
+               }
        }
-       raw_spin_unlock(&drvdata->spinlock);
+
        return sprintf(buf, "%#x\n", val);
 }
 
@@ -293,15 +297,16 @@ static ssize_t cti_reg32_store(struct device *dev, const char *buf,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
-       /* local store */
-       if (pcached_val)
-               *pcached_val = (u32)val;
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               /* local store */
+               if (pcached_val)
+                       *pcached_val = (u32)val;
+
+               /* write through if offset and enabled */
+               if ((reg_offset >= 0) && cti_active(config))
+                       cti_write_single_reg(drvdata, reg_offset, val);
+       }
 
-       /* write through if offset and enabled */
-       if ((reg_offset >= 0) && cti_active(config))
-               cti_write_single_reg(drvdata, reg_offset, val);
-       raw_spin_unlock(&drvdata->spinlock);
        return size;
 }
 
@@ -349,9 +354,9 @@ static ssize_t inout_sel_store(struct device *dev,
        if (val > (CTIINOUTEN_MAX - 1))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        drvdata->config.ctiinout_sel = val;
-       raw_spin_unlock(&drvdata->spinlock);
        return size;
 }
 static DEVICE_ATTR_RW(inout_sel);
@@ -364,10 +369,11 @@ static ssize_t inen_show(struct device *dev,
        int index;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
 
-       raw_spin_lock(&drvdata->spinlock);
-       index = drvdata->config.ctiinout_sel;
-       val = drvdata->config.ctiinen[index];
-       raw_spin_unlock(&drvdata->spinlock);
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               index = drvdata->config.ctiinout_sel;
+               val = drvdata->config.ctiinen[index];
+       }
+
        return sprintf(buf, "%#lx\n", val);
 }
 
@@ -383,14 +389,15 @@ static ssize_t inen_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        index = config->ctiinout_sel;
        config->ctiinen[index] = val;
 
        /* write through if enabled */
        if (cti_active(config))
                cti_write_single_reg(drvdata, CTIINEN(index), val);
-       raw_spin_unlock(&drvdata->spinlock);
+
        return size;
 }
 static DEVICE_ATTR_RW(inen);
@@ -403,10 +410,11 @@ static ssize_t outen_show(struct device *dev,
        int index;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
 
-       raw_spin_lock(&drvdata->spinlock);
-       index = drvdata->config.ctiinout_sel;
-       val = drvdata->config.ctiouten[index];
-       raw_spin_unlock(&drvdata->spinlock);
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               index = drvdata->config.ctiinout_sel;
+               val = drvdata->config.ctiouten[index];
+       }
+
        return sprintf(buf, "%#lx\n", val);
 }
 
@@ -422,14 +430,15 @@ static ssize_t outen_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        index = config->ctiinout_sel;
        config->ctiouten[index] = val;
 
        /* write through if enabled */
        if (cti_active(config))
                cti_write_single_reg(drvdata, CTIOUTEN(index), val);
-       raw_spin_unlock(&drvdata->spinlock);
+
        return size;
 }
 static DEVICE_ATTR_RW(outen);
@@ -463,7 +472,7 @@ static ssize_t appclear_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
 
        /* a 1'b1 in appclr clears down the same bit in appset*/
        config->ctiappset &= ~val;
@@ -471,7 +480,7 @@ static ssize_t appclear_store(struct device *dev,
        /* write through if enabled */
        if (cti_active(config))
                cti_write_single_reg(drvdata, CTIAPPCLEAR, val);
-       raw_spin_unlock(&drvdata->spinlock);
+
        return size;
 }
 static DEVICE_ATTR_WO(appclear);
@@ -487,12 +496,12 @@ static ssize_t apppulse_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
 
        /* write through if enabled */
        if (cti_active(config))
                cti_write_single_reg(drvdata, CTIAPPPULSE, val);
-       raw_spin_unlock(&drvdata->spinlock);
+
        return size;
 }
 static DEVICE_ATTR_WO(apppulse);
@@ -681,9 +690,9 @@ static ssize_t trig_filter_enable_show(struct device *dev,
        u32 val;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
 
-       raw_spin_lock(&drvdata->spinlock);
-       val = drvdata->config.trig_filter_enable;
-       raw_spin_unlock(&drvdata->spinlock);
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock)
+               val = drvdata->config.trig_filter_enable;
+
        return sprintf(buf, "%d\n", val);
 }
 
@@ -697,9 +706,9 @@ static ssize_t trig_filter_enable_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        drvdata->config.trig_filter_enable = !!val;
-       raw_spin_unlock(&drvdata->spinlock);
        return size;
 }
 static DEVICE_ATTR_RW(trig_filter_enable);
@@ -728,7 +737,7 @@ static ssize_t chan_xtrigs_reset_store(struct device *dev,
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
        struct cti_config *config = &drvdata->config;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
 
        /* clear the CTI trigger / channel programming registers */
        for (i = 0; i < config->nr_trig_max; i++) {
@@ -747,7 +756,6 @@ static ssize_t chan_xtrigs_reset_store(struct device *dev,
        if (cti_active(config))
                cti_write_all_hw_regs(drvdata);
 
-       raw_spin_unlock(&drvdata->spinlock);
        return size;
 }
 static DEVICE_ATTR_WO(chan_xtrigs_reset);
@@ -768,9 +776,9 @@ static ssize_t chan_xtrigs_sel_store(struct device *dev,
        if (val > (drvdata->config.nr_ctm_channels - 1))
                return -EINVAL;
 
-       raw_spin_lock(&drvdata->spinlock);
+       guard(raw_spinlock_irqsave)(&drvdata->spinlock);
+
        drvdata->config.xtrig_rchan_sel = val;
-       raw_spin_unlock(&drvdata->spinlock);
        return size;
 }
 
@@ -781,9 +789,8 @@ static ssize_t chan_xtrigs_sel_show(struct device *dev,
        unsigned long val;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
 
-       raw_spin_lock(&drvdata->spinlock);
-       val = drvdata->config.xtrig_rchan_sel;
-       raw_spin_unlock(&drvdata->spinlock);
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock)
+               val = drvdata->config.xtrig_rchan_sel;
 
        return sprintf(buf, "%ld\n", val);
 }
@@ -838,12 +845,12 @@ static ssize_t print_chan_list(struct device *dev,
        unsigned long inuse_bits = 0, chan_mask;
 
        /* scan regs to get bitmap of channels in use. */
-       raw_spin_lock(&drvdata->spinlock);
-       for (i = 0; i < config->nr_trig_max; i++) {
-               inuse_bits |= config->ctiinen[i];
-               inuse_bits |= config->ctiouten[i];
+       scoped_guard(raw_spinlock_irqsave, &drvdata->spinlock) {
+               for (i = 0; i < config->nr_trig_max; i++) {
+                       inuse_bits |= config->ctiinen[i];
+                       inuse_bits |= config->ctiouten[i];
+               }
        }
-       raw_spin_unlock(&drvdata->spinlock);
 
        /* inverse bits if printing free channels */
        if (!inuse)