Re: [PATCH v3 4/9] coresight-cti: change cti_drvdata spinlock's type to raw_spinlock_t - CoreSight

19 Dec 2024

On Mon, 16 Dec 2024 at 11:50, Yeoreum Yun yeoreum.yun@arm.com wrote:
...
In coresight-cti drivers, cti_drvdata->spinlock can be held during __schedule()
by perf_event_task_sched_out()/in().
Since cti_drvdata->spinlock type is spinlock_t and
perf_event_task_sched_out()/in() is called after acquiring rq_lock,
which is raw_spinlock_t (an unsleepable lock),
this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable.
To address this, change type cti_drvdata->spinlock in coresight-cti drivers,
which can be called by perf_event_task_sched_out()/in(),
from spinlock_t to raw_spinlock_t.
Signed-off-by: Yeoreum Yun yeoreum.yun@arm.com
.../hwtracing/coresight/coresight-cti-core.c  | 44 +++++------
 .../hwtracing/coresight/coresight-cti-sysfs.c | 76 +++++++++----------
 drivers/hwtracing/coresight/coresight-cti.h   |  2 +-
 3 files changed, 61 insertions(+), 61 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c
index d2b5a5718c29..80f6265e3740 100644
--- a/drivers/hwtracing/coresight/coresight-cti-core.c
+++ b/drivers/hwtracing/coresight/coresight-cti-core.c
@@ -93,7 +93,7 @@ static int cti_enable_hw(struct cti_drvdata *drvdata)
        unsigned long flags;
        int rc = 0;

  spin_lock_irqsave(&drvdata->spinlock, flags);




  raw_spin_lock_irqsave(&drvdata->spinlock, flags);

  /* no need to do anything if enabled or unpowered*/
  if (config->hw_enabled || !config->hw_powered)



@@ -108,7 +108,7 @@ static int cti_enable_hw(struct cti_drvdata *drvdata)
    config->hw_enabled = true;
    drvdata->config.enable_req_count++;


  spin_unlock_irqrestore(&drvdata->spinlock, flags);




  raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
  return rc;




cti_state_unchanged:
@@ -116,7 +116,7 @@ static int cti_enable_hw(struct cti_drvdata *drvdata)
    /* cannot enable due to error */

cti_err_not_enabled:

  spin_unlock_irqrestore(&drvdata->spinlock, flags);




  raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
  return rc;



}
@@ -125,7 +125,7 @@ static void cti_cpuhp_enable_hw(struct cti_drvdata *drvdata)
 {
        struct cti_config *config = &drvdata->config;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  config->hw_powered = true;

  /* no need to do anything if no enable request */



@@ -138,12 +138,12 @@ static void cti_cpuhp_enable_hw(struct cti_drvdata *drvdata)
    cti_write_all_hw_regs(drvdata);
    config->hw_enabled = true;


  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return;

  /* did not re-enable due to no claim / no request */



cti_hp_not_enabled:

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);



}
/* disable hardware */
@@ -153,7 +153,7 @@ static int cti_disable_hw(struct cti_drvdata *drvdata)
        struct coresight_device *csdev = drvdata->csdev;
        int ret = 0;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);

  /* don't allow negative refcounts, return an error */
  if (!drvdata->config.enable_req_count) {



@@ -177,12 +177,12 @@ static int cti_disable_hw(struct cti_drvdata *drvdata)
    coresight_disclaim_device_unlocked(csdev);
    CS_LOCK(drvdata->base);


  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return ret;

  /* not disabled this call */



cti_not_disabled:

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return ret;



}
@@ -198,11 +198,11 @@ void cti_write_intack(struct device *dev, u32 ackval)
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);
        struct cti_config *config = &drvdata->config;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  /* write if enabled */
  if (cti_active(config))
          cti_write_single_reg(drvdata, CTIINTACK, ackval);




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);



}
/*
@@ -369,7 +369,7 @@ 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));

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);

  /* read - modify write - the trigger / channel enable value */
  reg_value = direction == CTI_TRIG_IN ? config->ctiinen[trigger_idx] :



@@ -388,7 +388,7 @@ 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);

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return 0;



}
@@ -406,7 +406,7 @@ int cti_channel_gate_op(struct device *dev, enum cti_chan_gate_op op,
    chan_bitmask = BIT(channel_idx);



  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  reg_value = config->ctigate;
  switch (op) {
  case CTI_GATE_CHAN_ENABLE:



@@ -426,7 +426,7 @@ 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);
        }

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return err;



}
@@ -445,7 +445,7 @@ int cti_channel_setop(struct device *dev, enum cti_chan_set_op op,
    chan_bitmask = BIT(channel_idx);



  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  reg_value = config->ctiappset;
  switch (op) {
  case CTI_CHAN_SET:



@@ -473,7 +473,7 @@ 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);


  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);

  return err;



}
@@ -676,7 +676,7 @@ static int cti_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
        if (WARN_ON_ONCE(drvdata->ctidev.cpu != cpu))
                return NOTIFY_BAD;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);

  switch (cmd) {
  case CPU_PM_ENTER:



@@ -716,7 +716,7 @@ static int cti_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
        }
cti_notify_exit:

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return notify_res;



}
@@ -743,11 +743,11 @@ static int cti_dying_cpu(unsigned int cpu)
        if (!drvdata)
                return 0;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  drvdata->config.hw_powered = false;
  if (drvdata->config.hw_enabled)
          coresight_disclaim_device(drvdata->csdev);




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return 0;



}
@@ -888,7 +888,7 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
        drvdata->ctidev.ctm_id = 0;
        INIT_LIST_HEAD(&drvdata->ctidev.trig_cons);

  spin_lock_init(&drvdata->spinlock);




  raw_spin_lock_init(&drvdata->spinlock);

  /* initialise CTI driver config values */
  cti_set_default_config(dev, drvdata);



diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
index d25dd2737b49..572b80ee96fb 100644
--- 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);

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  enable_req = drvdata->config.enable_req_count;
  powered = drvdata->config.hw_powered;
  enabled = drvdata->config.hw_enabled;




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);

  if (powered)
          return sprintf(buf, "%d\n", enabled);



@@ -134,9 +134,9 @@ static ssize_t powered_show(struct device *dev,
        bool powered;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  powered = drvdata->config.hw_powered;




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);

  return sprintf(buf, "%d\n", powered);



}
@@ -181,10 +181,10 @@ static ssize_t coresight_cti_reg_show(struct device *dev,
        u32 val = 0;
    pm_runtime_get_sync(dev->parent);


  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  if (drvdata->config.hw_powered)
          val = readl_relaxed(drvdata->base + cti_attr->off);




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  pm_runtime_put_sync(dev->parent);
  return sysfs_emit(buf, "0x%x\n", val);



}
@@ -202,10 +202,10 @@ static __maybe_unused ssize_t coresight_cti_reg_store(struct device *dev,
                return -EINVAL;
    pm_runtime_get_sync(dev->parent);


  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  if (drvdata->config.hw_powered)
          cti_write_single_reg(drvdata, cti_attr->off, val);




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  pm_runtime_put_sync(dev->parent);
  return size;



}
@@ -264,7 +264,7 @@ 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;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  if ((reg_offset >= 0) && cti_active(config)) {
          CS_UNLOCK(drvdata->base);
          val = readl_relaxed(drvdata->base + reg_offset);



@@ -274,7 +274,7 @@ static ssize_t cti_reg32_show(struct device *dev, char *buf,
        } else if (pcached_val) {
                val = *pcached_val;
        }

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return sprintf(buf, "%#x\n", val);



}
@@ -293,7 +293,7 @@ static ssize_t cti_reg32_store(struct device *dev, const char *buf,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  /* local store */
  if (pcached_val)
          *pcached_val = (u32)val;



@@ -301,7 +301,7 @@ static ssize_t cti_reg32_store(struct device *dev, const char *buf,
        /* write through if offset and enabled */
        if ((reg_offset >= 0) && cti_active(config))
                cti_write_single_reg(drvdata, reg_offset, val);

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
@@ -349,9 +349,9 @@ static ssize_t inout_sel_store(struct device *dev,
        if (val > (CTIINOUTEN_MAX - 1))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  drvdata->config.ctiinout_sel = val;




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
 static DEVICE_ATTR_RW(inout_sel);
@@ -364,10 +364,10 @@ static ssize_t inen_show(struct device *dev,
        int index;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  index = drvdata->config.ctiinout_sel;
  val = drvdata->config.ctiinen[index];




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return sprintf(buf, "%#lx\n", val);



}
@@ -383,14 +383,14 @@ static ssize_t inen_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&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);




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
 static DEVICE_ATTR_RW(inen);
@@ -403,10 +403,10 @@ static ssize_t outen_show(struct device *dev,
        int index;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  index = drvdata->config.ctiinout_sel;
  val = drvdata->config.ctiouten[index];




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return sprintf(buf, "%#lx\n", val);



}
@@ -422,14 +422,14 @@ static ssize_t outen_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&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);




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
 static DEVICE_ATTR_RW(outen);
@@ -463,7 +463,7 @@ static ssize_t appclear_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);

  /* a 1'b1 in appclr clears down the same bit in appset*/
  config->ctiappset &= ~val;



@@ -471,7 +471,7 @@ static ssize_t appclear_store(struct device *dev,
        /* write through if enabled */
        if (cti_active(config))
                cti_write_single_reg(drvdata, CTIAPPCLEAR, val);

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
 static DEVICE_ATTR_WO(appclear);
@@ -487,12 +487,12 @@ static ssize_t apppulse_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);

  /* write through if enabled */
  if (cti_active(config))
          cti_write_single_reg(drvdata, CTIAPPPULSE, val);




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
 static DEVICE_ATTR_WO(apppulse);
@@ -681,9 +681,9 @@ static ssize_t trig_filter_enable_show(struct device *dev,
        u32 val;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  val = drvdata->config.trig_filter_enable;




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return sprintf(buf, "%d\n", val);



}
@@ -697,9 +697,9 @@ static ssize_t trig_filter_enable_store(struct device *dev,
        if (kstrtoul(buf, 0, &val))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  drvdata->config.trig_filter_enable = !!val;




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
 static DEVICE_ATTR_RW(trig_filter_enable);
@@ -728,7 +728,7 @@ 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;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);

  /* clear the CTI trigger / channel programming registers */
  for (i = 0; i < config->nr_trig_max; i++) {



@@ -747,7 +747,7 @@ static ssize_t chan_xtrigs_reset_store(struct device *dev,
        if (cti_active(config))
                cti_write_all_hw_regs(drvdata);

  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
 static DEVICE_ATTR_WO(chan_xtrigs_reset);
@@ -768,9 +768,9 @@ static ssize_t chan_xtrigs_sel_store(struct device *dev,
        if (val > (drvdata->config.nr_ctm_channels - 1))
                return -EINVAL;

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  drvdata->config.xtrig_rchan_sel = val;




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);
  return size;



}
@@ -781,9 +781,9 @@ static ssize_t chan_xtrigs_sel_show(struct device *dev,
        unsigned long val;
        struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent);

  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  val = drvdata->config.xtrig_rchan_sel;




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);

  return sprintf(buf, "%ld\n", val);



}
@@ -838,12 +838,12 @@ 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. */


  spin_lock(&drvdata->spinlock);




  raw_spin_lock(&drvdata->spinlock);
  for (i = 0; i < config->nr_trig_max; i++) {
          inuse_bits |= config->ctiinen[i];
          inuse_bits |= config->ctiouten[i];
  }




  spin_unlock(&drvdata->spinlock);




  raw_spin_unlock(&drvdata->spinlock);

  /* inverse bits if printing free channels */
  if (!inuse)



diff --git a/drivers/hwtracing/coresight/coresight-cti.h b/drivers/hwtracing/coresight/coresight-cti.h
index cb9ee616d01f..16e310e7e9d4 100644
--- a/drivers/hwtracing/coresight/coresight-cti.h
+++ b/drivers/hwtracing/coresight/coresight-cti.h
@@ -175,7 +175,7 @@ struct cti_drvdata {
        void __iomem *base;
        struct coresight_device *csdev;
        struct cti_device ctidev;

  spinlock_t spinlock;




  raw_spinlock_t spinlock;
  struct cti_config config;
  struct list_head node;
  void (*csdev_release)(struct device *dev);



--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
Reviewed-by: Mike Leach mike.leach@linaro.org
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

    