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Message-Id: <20241125094816.365472-6-yeoreum.yun@arm.com>
Date: Mon, 25 Nov 2024 09:48:12 +0000
From: Yeoreum Yun <yeoreum.yun@....com>
To: suzuki.poulose@....com,
mike.leach@...aro.org,
james.clark@...aro.org,
alexander.shishkin@...ux.intel.com,
bigeasy@...utronix.de,
clrkwllms@...nel.org,
rostedt@...dmis.org
Cc: coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
linux-rt-devel@...ts.linux.dev,
nd@....com,
Levi Yun <yeoreum.yun@....com>
Subject: [PATCH 5/9] coresight-etb10: change etb_drvdata spinlock's type to raw_spinlock_t
From: Levi Yun <yeoreum.yun@....com>
In coresight-etb10 drivers, etb_drvdata->spinlock can be held
during __schedule() by perf_event_task_sched_out()/in().
Since etb_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 etb_drvdata->spinlock in coresight-etb10 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@....com>
---
drivers/hwtracing/coresight/coresight-etb10.c | 62 +++++++------------
1 file changed, 22 insertions(+), 40 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index aea9ac9c4bd0..ec439f8fbc1e 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -84,7 +84,7 @@ struct etb_drvdata {
struct clk *atclk;
struct coresight_device *csdev;
struct miscdevice miscdev;
- spinlock_t spinlock;
+ raw_spinlock_t spinlock;
local_t reading;
pid_t pid;
u8 *buf;
@@ -141,56 +141,47 @@ static int etb_enable_hw(struct etb_drvdata *drvdata)
static int etb_enable_sysfs(struct coresight_device *csdev)
{
- int ret = 0;
- unsigned long flags;
+ int ret;
struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
- spin_lock_irqsave(&drvdata->spinlock, flags);
+ guard(raw_spinlock_irqsave)(&drvdata->spinlock);
/* Don't messup with perf sessions. */
- if (coresight_get_mode(csdev) == CS_MODE_PERF) {
- ret = -EBUSY;
- goto out;
- }
+ if (coresight_get_mode(csdev) == CS_MODE_PERF)
+ return -EBUSY;
if (coresight_get_mode(csdev) == CS_MODE_DISABLED) {
ret = etb_enable_hw(drvdata);
if (ret)
- goto out;
+ return ret;
coresight_set_mode(csdev, CS_MODE_SYSFS);
}
csdev->refcnt++;
-out:
- spin_unlock_irqrestore(&drvdata->spinlock, flags);
- return ret;
+
+ return 0;
}
static int etb_enable_perf(struct coresight_device *csdev, void *data)
{
- int ret = 0;
+ int ret;
pid_t pid;
- unsigned long flags;
struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
struct perf_output_handle *handle = data;
struct cs_buffers *buf = etm_perf_sink_config(handle);
- spin_lock_irqsave(&drvdata->spinlock, flags);
+ guard(raw_spinlock_irqsave)(&drvdata->spinlock);
/* No need to continue if the component is already in used by sysFS. */
- if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
- ret = -EBUSY;
- goto out;
- }
+ if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS)
+ return -EBUSY;
/* Get a handle on the pid of the process to monitor */
pid = buf->pid;
- if (drvdata->pid != -1 && drvdata->pid != pid) {
- ret = -EBUSY;
- goto out;
- }
+ if (drvdata->pid != -1 && drvdata->pid != pid)
+ return -EBUSY;
/*
* No HW configuration is needed if the sink is already in
@@ -198,7 +189,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data)
*/
if (drvdata->pid == pid) {
csdev->refcnt++;
- goto out;
+ return 0;
}
/*
@@ -208,7 +199,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data)
*/
ret = etb_set_buffer(csdev, handle);
if (ret)
- goto out;
+ return ret;
ret = etb_enable_hw(drvdata);
if (!ret) {
@@ -218,8 +209,6 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data)
csdev->refcnt++;
}
-out:
- spin_unlock_irqrestore(&drvdata->spinlock, flags);
return ret;
}
@@ -350,13 +339,11 @@ static void etb_disable_hw(struct etb_drvdata *drvdata)
static int etb_disable(struct coresight_device *csdev)
{
struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
- unsigned long flags;
- spin_lock_irqsave(&drvdata->spinlock, flags);
+ guard(raw_spinlock_irqsave)(&drvdata->spinlock);
csdev->refcnt--;
if (csdev->refcnt) {
- spin_unlock_irqrestore(&drvdata->spinlock, flags);
return -EBUSY;
}
@@ -366,7 +353,6 @@ static int etb_disable(struct coresight_device *csdev)
/* Dissociate from monitored process. */
drvdata->pid = -1;
coresight_set_mode(csdev, CS_MODE_DISABLED);
- spin_unlock_irqrestore(&drvdata->spinlock, flags);
dev_dbg(&csdev->dev, "ETB disabled\n");
return 0;
@@ -434,7 +420,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
const u32 *barrier;
u32 read_ptr, write_ptr, capacity;
u32 status, read_data;
- unsigned long offset, to_read = 0, flags;
+ unsigned long offset, to_read = 0;
struct cs_buffers *buf = sink_config;
struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
@@ -443,11 +429,11 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS;
- spin_lock_irqsave(&drvdata->spinlock, flags);
+ guard(raw_spinlock_irqsave)(&drvdata->spinlock);
/* Don't do anything if another tracer is using this sink */
if (csdev->refcnt != 1)
- goto out;
+ return 0;
__etb_disable_hw(drvdata);
CS_UNLOCK(drvdata->base);
@@ -565,8 +551,6 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
__etb_enable_hw(drvdata);
CS_LOCK(drvdata->base);
-out:
- spin_unlock_irqrestore(&drvdata->spinlock, flags);
return to_read;
}
@@ -585,15 +569,13 @@ static const struct coresight_ops etb_cs_ops = {
static void etb_dump(struct etb_drvdata *drvdata)
{
- unsigned long flags;
+ guard(raw_spinlock_irqsave)(&drvdata->spinlock);
- spin_lock_irqsave(&drvdata->spinlock, flags);
if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
__etb_disable_hw(drvdata);
etb_dump_hw(drvdata);
__etb_enable_hw(drvdata);
}
- spin_unlock_irqrestore(&drvdata->spinlock, flags);
dev_dbg(&drvdata->csdev->dev, "ETB dumped\n");
}
@@ -746,7 +728,7 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id)
drvdata->base = base;
desc.access = CSDEV_ACCESS_IOMEM(base);
- spin_lock_init(&drvdata->spinlock);
+ raw_spin_lock_init(&drvdata->spinlock);
drvdata->buffer_depth = etb_get_buffer_depth(drvdata);
--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
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