When tracing etm data of multiple threads on multiple cpus through perf
interface, some link devices are shared between paths of different cpus.
It creates race conditions when different cpus wants to enable/disable
the same link device at the same time.
Example 1:
Two cpus want to enable different ports of a coresight funnel, thus
calling the funnel enable operation at the same time. But the funnel
enable operation isn't reentrantable.
Example 2:
For an enabled coresight dynamic replicator with refcnt=1, one cpu wants
to disable it, while another cpu wants to enable it. Ideally we still have
an enabled replicator with refcnt=1 at the end. But in reality the result
is uncertain.
Since coresight devices claim themselves when enabled for self-hosted
usage, the race conditions above usually make the link devices not usable
after many cycles.
To fix the race conditions, this patch uses spinlocks to serialize
enabling/disabling link devices.
Fixes: a06ae8609b3d ("coresight: add CoreSight core layer framework")
Signed-off-by: Yabin Cui <yabinc@google.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: stable <stable@vger.kernel.org> # 5.3
Link: https://lore.kernel.org/r/20191104181251.26732-14-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* @atclk: optional clock for the core parts of the funnel.
* @csdev: component vitals needed by the framework.
* @priority: port selection order.
+ * @spinlock: serialize enable/disable operations.
*/
struct funnel_drvdata {
void __iomem *base;
struct clk *atclk;
struct coresight_device *csdev;
unsigned long priority;
+ spinlock_t spinlock;
};
static int dynamic_funnel_enable_hw(struct funnel_drvdata *drvdata, int port)
{
int rc = 0;
struct funnel_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
-
- if (drvdata->base)
- rc = dynamic_funnel_enable_hw(drvdata, inport);
-
+ unsigned long flags;
+ bool first_enable = false;
+
+ spin_lock_irqsave(&drvdata->spinlock, flags);
+ if (atomic_read(&csdev->refcnt[inport]) == 0) {
+ if (drvdata->base)
+ rc = dynamic_funnel_enable_hw(drvdata, inport);
+ if (!rc)
+ first_enable = true;
+ }
if (!rc)
+ atomic_inc(&csdev->refcnt[inport]);
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+ if (first_enable)
dev_dbg(&csdev->dev, "FUNNEL inport %d enabled\n", inport);
return rc;
}
int outport)
{
struct funnel_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+ unsigned long flags;
+ bool last_disable = false;
+
+ spin_lock_irqsave(&drvdata->spinlock, flags);
+ if (atomic_dec_return(&csdev->refcnt[inport]) == 0) {
+ if (drvdata->base)
+ dynamic_funnel_disable_hw(drvdata, inport);
+ last_disable = true;
+ }
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);
- if (drvdata->base)
- dynamic_funnel_disable_hw(drvdata, inport);
-
- dev_dbg(&csdev->dev, "FUNNEL inport %d disabled\n", inport);
+ if (last_disable)
+ dev_dbg(&csdev->dev, "FUNNEL inport %d disabled\n", inport);
}
static const struct coresight_ops_link funnel_link_ops = {
* whether this one is programmable or not.
* @atclk: optional clock for the core parts of the replicator.
* @csdev: component vitals needed by the framework
+ * @spinlock: serialize enable/disable operations.
*/
struct replicator_drvdata {
void __iomem *base;
struct clk *atclk;
struct coresight_device *csdev;
+ spinlock_t spinlock;
};
static void dynamic_replicator_reset(struct replicator_drvdata *drvdata)
{
int rc = 0;
struct replicator_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
-
- if (drvdata->base)
- rc = dynamic_replicator_enable(drvdata, inport, outport);
+ unsigned long flags;
+ bool first_enable = false;
+
+ spin_lock_irqsave(&drvdata->spinlock, flags);
+ if (atomic_read(&csdev->refcnt[outport]) == 0) {
+ if (drvdata->base)
+ rc = dynamic_replicator_enable(drvdata, inport,
+ outport);
+ if (!rc)
+ first_enable = true;
+ }
if (!rc)
+ atomic_inc(&csdev->refcnt[outport]);
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+ if (first_enable)
dev_dbg(&csdev->dev, "REPLICATOR enabled\n");
return rc;
}
int outport)
{
struct replicator_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+ unsigned long flags;
+ bool last_disable = false;
+
+ spin_lock_irqsave(&drvdata->spinlock, flags);
+ if (atomic_dec_return(&csdev->refcnt[outport]) == 0) {
+ if (drvdata->base)
+ dynamic_replicator_disable(drvdata, inport, outport);
+ last_disable = true;
+ }
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);
- if (drvdata->base)
- dynamic_replicator_disable(drvdata, inport, outport);
- dev_dbg(&csdev->dev, "REPLICATOR disabled\n");
+ if (last_disable)
+ dev_dbg(&csdev->dev, "REPLICATOR disabled\n");
}
static const struct coresight_ops_link replicator_link_ops = {
static int tmc_enable_etf_link(struct coresight_device *csdev,
int inport, int outport)
{
- int ret;
+ int ret = 0;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+ bool first_enable = false;
spin_lock_irqsave(&drvdata->spinlock, flags);
if (drvdata->reading) {
return -EBUSY;
}
- ret = tmc_etf_enable_hw(drvdata);
+ if (atomic_read(&csdev->refcnt[0]) == 0) {
+ ret = tmc_etf_enable_hw(drvdata);
+ if (!ret) {
+ drvdata->mode = CS_MODE_SYSFS;
+ first_enable = true;
+ }
+ }
if (!ret)
- drvdata->mode = CS_MODE_SYSFS;
+ atomic_inc(&csdev->refcnt[0]);
spin_unlock_irqrestore(&drvdata->spinlock, flags);
- if (!ret)
+ if (first_enable)
dev_dbg(&csdev->dev, "TMC-ETF enabled\n");
return ret;
}
{
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+ bool last_disable = false;
spin_lock_irqsave(&drvdata->spinlock, flags);
if (drvdata->reading) {
return;
}
- tmc_etf_disable_hw(drvdata);
- drvdata->mode = CS_MODE_DISABLED;
+ if (atomic_dec_return(&csdev->refcnt[0]) == 0) {
+ tmc_etf_disable_hw(drvdata);
+ drvdata->mode = CS_MODE_DISABLED;
+ last_disable = true;
+ }
spin_unlock_irqrestore(&drvdata->spinlock, flags);
- dev_dbg(&csdev->dev, "TMC-ETF disabled\n");
+ if (last_disable)
+ dev_dbg(&csdev->dev, "TMC-ETF disabled\n");
}
static void *tmc_alloc_etf_buffer(struct coresight_device *csdev,
struct coresight_device *parent,
struct coresight_device *child)
{
- int ret;
+ int ret = 0;
int link_subtype;
- int refport, inport, outport;
+ int inport, outport;
if (!parent || !child)
return -EINVAL;
outport = coresight_find_link_outport(csdev, child);
link_subtype = csdev->subtype.link_subtype;
- if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG)
- refport = inport;
- else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT)
- refport = outport;
- else
- refport = 0;
-
- if (refport < 0)
- return refport;
+ if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG && inport < 0)
+ return inport;
+ if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT && outport < 0)
+ return outport;
- if (atomic_inc_return(&csdev->refcnt[refport]) == 1) {
- if (link_ops(csdev)->enable) {
- ret = link_ops(csdev)->enable(csdev, inport, outport);
- if (ret) {
- atomic_dec(&csdev->refcnt[refport]);
- return ret;
- }
- }
- }
-
- csdev->enable = true;
+ if (link_ops(csdev)->enable)
+ ret = link_ops(csdev)->enable(csdev, inport, outport);
+ if (!ret)
+ csdev->enable = true;
- return 0;
+ return ret;
}
static void coresight_disable_link(struct coresight_device *csdev,
{
int i, nr_conns;
int link_subtype;
- int refport, inport, outport;
+ int inport, outport;
if (!parent || !child)
return;
link_subtype = csdev->subtype.link_subtype;
if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG) {
- refport = inport;
nr_conns = csdev->pdata->nr_inport;
} else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT) {
- refport = outport;
nr_conns = csdev->pdata->nr_outport;
} else {
- refport = 0;
nr_conns = 1;
}
- if (atomic_dec_return(&csdev->refcnt[refport]) == 0) {
- if (link_ops(csdev)->disable)
- link_ops(csdev)->disable(csdev, inport, outport);
- }
+ if (link_ops(csdev)->disable)
+ link_ops(csdev)->disable(csdev, inport, outport);
for (i = 0; i < nr_conns; i++)
if (atomic_read(&csdev->refcnt[i]) != 0)