[PATCH] mfd: ezx-pcap: replace mutex_lock with spin_lock

From: Fuqian Huang
Date: Tue Aug 13 2019 - 06:31:52 EST

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As mutex_lock might sleep.
Function pcap_adc_irq is an interrupt handler.
The use of mutex_lock in pcap_adc_irq may cause sleep
in IRQ context.
Replace mutex_lock with spin_lock to avoid this.

Signed-off-by: Fuqian Huang <huangfq.daxian@xxxxxxxxx>
---
drivers/mfd/ezx-pcap.c | 53 ++++++++++++++++++++++++++++----------------------
1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/drivers/mfd/ezx-pcap.c b/drivers/mfd/ezx-pcap.c
index f505e3e1274b..70fa18b04ad2 100644
--- a/drivers/mfd/ezx-pcap.c
+++ b/drivers/mfd/ezx-pcap.c
@@ -35,7 +35,7 @@ struct pcap_chip {

/* IO */
u32 buf;
- struct mutex io_mutex;
+ spinlock_t io_lock;

/* IRQ */
unsigned int irq_base;
@@ -48,7 +48,7 @@ struct pcap_chip {
struct pcap_adc_request *adc_queue[PCAP_ADC_MAXQ];
u8 adc_head;
u8 adc_tail;
- struct mutex adc_mutex;
+ spinlock_t adc_lock;
};

/* IO */
@@ -76,14 +76,15 @@ static int ezx_pcap_putget(struct pcap_chip *pcap, u32 *data)

int ezx_pcap_write(struct pcap_chip *pcap, u8 reg_num, u32 value)
{
+ unsigned long flags;
int ret;

- mutex_lock(&pcap->io_mutex);
+ spin_lock_irqsave(&pcap->io_lock, flags);
value &= PCAP_REGISTER_VALUE_MASK;
value |= PCAP_REGISTER_WRITE_OP_BIT
| (reg_num << PCAP_REGISTER_ADDRESS_SHIFT);
ret = ezx_pcap_putget(pcap, &value);
- mutex_unlock(&pcap->io_mutex);
+ spin_unlock_irqrestore(&pcap->io_lock, flags);

return ret;
}
@@ -91,14 +92,15 @@ EXPORT_SYMBOL_GPL(ezx_pcap_write);

int ezx_pcap_read(struct pcap_chip *pcap, u8 reg_num, u32 *value)
{
+ unsigned long flags;
int ret;

- mutex_lock(&pcap->io_mutex);
+ spin_lock_irqsave(&pcap->io_lock, flags);
*value = PCAP_REGISTER_READ_OP_BIT
| (reg_num << PCAP_REGISTER_ADDRESS_SHIFT);

ret = ezx_pcap_putget(pcap, value);
- mutex_unlock(&pcap->io_mutex);
+ spin_unlock_irqrestore(&pcap->io_lock, flags);

return ret;
}
@@ -106,11 +108,12 @@ EXPORT_SYMBOL_GPL(ezx_pcap_read);

int ezx_pcap_set_bits(struct pcap_chip *pcap, u8 reg_num, u32 mask, u32 val)
{
+ unsigned long flags;
int ret;
u32 tmp = PCAP_REGISTER_READ_OP_BIT |
(reg_num << PCAP_REGISTER_ADDRESS_SHIFT);

- mutex_lock(&pcap->io_mutex);
+ spin_lock_irqsave(&pcap->io_lock, flags);
ret = ezx_pcap_putget(pcap, &tmp);
if (ret)
goto out_unlock;
@@ -121,7 +124,7 @@ int ezx_pcap_set_bits(struct pcap_chip *pcap, u8 reg_num, u32 mask, u32 val)

ret = ezx_pcap_putget(pcap, &tmp);
out_unlock:
- mutex_unlock(&pcap->io_mutex);
+ spin_unlock_irqrestore(&pcap->io_lock, flags);

return ret;
}
@@ -212,14 +215,15 @@ static void pcap_irq_handler(struct irq_desc *desc)
/* ADC */
void pcap_set_ts_bits(struct pcap_chip *pcap, u32 bits)
{
+ unsigned long flags;
u32 tmp;

- mutex_lock(&pcap->adc_mutex);
+ spin_lock_irqsave(&pcap->adc_lock, flags);
ezx_pcap_read(pcap, PCAP_REG_ADC, &tmp);
tmp &= ~(PCAP_ADC_TS_M_MASK | PCAP_ADC_TS_REF_LOWPWR);
tmp |= bits & (PCAP_ADC_TS_M_MASK | PCAP_ADC_TS_REF_LOWPWR);
ezx_pcap_write(pcap, PCAP_REG_ADC, tmp);
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock_irqrestore(&pcap->adc_lock, flags);
}
EXPORT_SYMBOL_GPL(pcap_set_ts_bits);

@@ -234,15 +238,16 @@ static void pcap_disable_adc(struct pcap_chip *pcap)

static void pcap_adc_trigger(struct pcap_chip *pcap)
{
+ unsigned long flags;
u32 tmp;
u8 head;

- mutex_lock(&pcap->adc_mutex);
+ spin_lock_irqsave(&pcap->adc_lock, flags);
head = pcap->adc_head;
if (!pcap->adc_queue[head]) {
/* queue is empty, save power */
pcap_disable_adc(pcap);
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock_irqrestore(&pcap->adc_lock, flags);
return;
}
/* start conversion on requested bank, save TS_M bits */
@@ -254,7 +259,7 @@ static void pcap_adc_trigger(struct pcap_chip *pcap)
tmp |= PCAP_ADC_AD_SEL1;

ezx_pcap_write(pcap, PCAP_REG_ADC, tmp);
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock_irqrestore(&pcap->adc_lock, flags);
ezx_pcap_write(pcap, PCAP_REG_ADR, PCAP_ADR_ASC);
}

@@ -265,11 +270,11 @@ static irqreturn_t pcap_adc_irq(int irq, void *_pcap)
u16 res[2];
u32 tmp;

- mutex_lock(&pcap->adc_mutex);
+ spin_lock(&pcap->adc_lock);
req = pcap->adc_queue[pcap->adc_head];

if (WARN(!req, "adc irq without pending request\n")) {
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock(&pcap->adc_lock);
return IRQ_HANDLED;
}

@@ -285,7 +290,7 @@ static irqreturn_t pcap_adc_irq(int irq, void *_pcap)

pcap->adc_queue[pcap->adc_head] = NULL;
pcap->adc_head = (pcap->adc_head + 1) & (PCAP_ADC_MAXQ - 1);
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock(&pcap->adc_lock);

/* pass the results and release memory */
req->callback(req->data, res);
@@ -301,6 +306,7 @@ int pcap_adc_async(struct pcap_chip *pcap, u8 bank, u32 flags, u8 ch[],
void *callback, void *data)
{
struct pcap_adc_request *req;
+ unsigned long irq_flags;

/* This will be freed after we have a result */
req = kmalloc(sizeof(struct pcap_adc_request), GFP_KERNEL);
@@ -314,15 +320,15 @@ int pcap_adc_async(struct pcap_chip *pcap, u8 bank, u32 flags, u8 ch[],
req->callback = callback;
req->data = data;

- mutex_lock(&pcap->adc_mutex);
+ spin_lock_irqsave(&pcap->adc_lock, irq_flags);
if (pcap->adc_queue[pcap->adc_tail]) {
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock_irqrestore(&pcap->adc_lock, irq_flags);
kfree(req);
return -EBUSY;
}
pcap->adc_queue[pcap->adc_tail] = req;
pcap->adc_tail = (pcap->adc_tail + 1) & (PCAP_ADC_MAXQ - 1);
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock_irqrestore(&pcap->adc_lock, irq_flags);

/* start conversion */
pcap_adc_trigger(pcap);
@@ -389,16 +395,17 @@ static int pcap_add_subdev(struct pcap_chip *pcap,
static int ezx_pcap_remove(struct spi_device *spi)
{
struct pcap_chip *pcap = spi_get_drvdata(spi);
+ unsigned long flags;
int i;

/* remove all registered subdevs */
device_for_each_child(&spi->dev, NULL, pcap_remove_subdev);

/* cleanup ADC */
- mutex_lock(&pcap->adc_mutex);
+ spin_lock_irqsave(&pcap->adc_lock, flags);
for (i = 0; i < PCAP_ADC_MAXQ; i++)
kfree(pcap->adc_queue[i]);
- mutex_unlock(&pcap->adc_mutex);
+ spin_unlock_irqrestore(&pcap->adc_lock, flags);

/* cleanup irqchip */
for (i = pcap->irq_base; i < (pcap->irq_base + PCAP_NIRQS); i++)
@@ -426,8 +433,8 @@ static int ezx_pcap_probe(struct spi_device *spi)
goto ret;
}

- mutex_init(&pcap->io_mutex);
- mutex_init(&pcap->adc_mutex);
+ spin_lock_init(&pcap->io_lock);
+ spin_lock_init(&pcap->adc_lock);
INIT_WORK(&pcap->isr_work, pcap_isr_work);
INIT_WORK(&pcap->msr_work, pcap_msr_work);
spi_set_drvdata(spi, pcap);
--
2.11.0

Next message: Colin King: "[PATCH] drm/amdgpu/powerplay: fix spelling mistake "unsuported" -> "unsupported""
Previous message: Nitesh Narayan Lal: "Re: [RFC][Patch v12 1/2] mm: page_reporting: core infrastructure"
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