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Message-Id: <20240628152543.281105-1-piotr.wojtaszczyk@timesys.com>
Date: Fri, 28 Jun 2024 17:25:42 +0200
From: Piotr Wojtaszczyk <piotr.wojtaszczyk@...esys.com>
To: Vladimir Zapolskiy <vz@...ia.com>,
Piotr Wojtaszczyk <piotr.wojtaszczyk@...esys.com>,
Andi Shyti <andi.shyti@...nel.org>,
linux-arm-kernel@...ts.infradead.org,
linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [Patch v6] i2c: pnx: Fix potential deadlock warning from del_timer_sync() call in isr
When del_timer_sync() is called in an interrupt context it throws a warning
because of potential deadlock. The timer is used only to exit from
wait_for_completion() after a timeout so replacing the call with
wait_for_completion_timeout() allows to remove the problematic timer and
its related functions altogether.
Signed-off-by: Piotr Wojtaszczyk <piotr.wojtaszczyk@...esys.com>
---
Changes for v6:
- Fixed typo in the patch subject
Changes for v5:
- Replaced wait_for_completion() with wait_for_completion_timeout().
- Removed unneded "alg_data->mif.timer" and its functions
- Request irq with devm_request_irq() as before the patch
- Renamed the patch and reword description for the new way to fix
the warning
Changes for v4:
- Request irq with devm_request_threaded_irq() to prevent the warning
drivers/i2c/busses/i2c-pnx.c | 48 ++++++++----------------------------
1 file changed, 10 insertions(+), 38 deletions(-)
diff --git a/drivers/i2c/busses/i2c-pnx.c b/drivers/i2c/busses/i2c-pnx.c
index a12525b3186b..f448505d5468 100644
--- a/drivers/i2c/busses/i2c-pnx.c
+++ b/drivers/i2c/busses/i2c-pnx.c
@@ -15,7 +15,6 @@
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/i2c.h>
-#include <linux/timer.h>
#include <linux/completion.h>
#include <linux/platform_device.h>
#include <linux/io.h>
@@ -32,7 +31,6 @@ struct i2c_pnx_mif {
int ret; /* Return value */
int mode; /* Interface mode */
struct completion complete; /* I/O completion */
- struct timer_list timer; /* Timeout */
u8 * buf; /* Data buffer */
int len; /* Length of data buffer */
int order; /* RX Bytes to order via TX */
@@ -117,24 +115,6 @@ static inline int wait_reset(struct i2c_pnx_algo_data *data)
return (timeout <= 0);
}
-static inline void i2c_pnx_arm_timer(struct i2c_pnx_algo_data *alg_data)
-{
- struct timer_list *timer = &alg_data->mif.timer;
- unsigned long expires = msecs_to_jiffies(alg_data->timeout);
-
- if (expires <= 1)
- expires = 2;
-
- del_timer_sync(timer);
-
- dev_dbg(&alg_data->adapter.dev, "Timer armed at %lu plus %lu jiffies.\n",
- jiffies, expires);
-
- timer->expires = jiffies + expires;
-
- add_timer(timer);
-}
-
/**
* i2c_pnx_start - start a device
* @slave_addr: slave address
@@ -259,8 +239,6 @@ static int i2c_pnx_master_xmit(struct i2c_pnx_algo_data *alg_data)
~(mcntrl_afie | mcntrl_naie | mcntrl_drmie),
I2C_REG_CTL(alg_data));
- del_timer_sync(&alg_data->mif.timer);
-
dev_dbg(&alg_data->adapter.dev,
"%s(): Waking up xfer routine.\n",
__func__);
@@ -276,8 +254,6 @@ static int i2c_pnx_master_xmit(struct i2c_pnx_algo_data *alg_data)
~(mcntrl_afie | mcntrl_naie | mcntrl_drmie),
I2C_REG_CTL(alg_data));
- /* Stop timer. */
- del_timer_sync(&alg_data->mif.timer);
dev_dbg(&alg_data->adapter.dev,
"%s(): Waking up xfer routine after zero-xfer.\n",
__func__);
@@ -364,8 +340,6 @@ static int i2c_pnx_master_rcv(struct i2c_pnx_algo_data *alg_data)
mcntrl_drmie | mcntrl_daie);
iowrite32(ctl, I2C_REG_CTL(alg_data));
- /* Kill timer. */
- del_timer_sync(&alg_data->mif.timer);
complete(&alg_data->mif.complete);
}
}
@@ -400,8 +374,6 @@ static irqreturn_t i2c_pnx_interrupt(int irq, void *dev_id)
mcntrl_drmie);
iowrite32(ctl, I2C_REG_CTL(alg_data));
- /* Stop timer, to prevent timeout. */
- del_timer_sync(&alg_data->mif.timer);
complete(&alg_data->mif.complete);
} else if (stat & mstatus_nai) {
/* Slave did not acknowledge, generate a STOP */
@@ -419,8 +391,6 @@ static irqreturn_t i2c_pnx_interrupt(int irq, void *dev_id)
/* Our return value. */
alg_data->mif.ret = -EIO;
- /* Stop timer, to prevent timeout. */
- del_timer_sync(&alg_data->mif.timer);
complete(&alg_data->mif.complete);
} else {
/*
@@ -453,9 +423,8 @@ static irqreturn_t i2c_pnx_interrupt(int irq, void *dev_id)
return IRQ_HANDLED;
}
-static void i2c_pnx_timeout(struct timer_list *t)
+static void i2c_pnx_timeout(struct i2c_pnx_algo_data *alg_data)
{
- struct i2c_pnx_algo_data *alg_data = from_timer(alg_data, t, mif.timer);
u32 ctl;
dev_err(&alg_data->adapter.dev,
@@ -472,7 +441,6 @@ static void i2c_pnx_timeout(struct timer_list *t)
iowrite32(ctl, I2C_REG_CTL(alg_data));
wait_reset(alg_data);
alg_data->mif.ret = -EIO;
- complete(&alg_data->mif.complete);
}
static inline void bus_reset_if_active(struct i2c_pnx_algo_data *alg_data)
@@ -514,6 +482,7 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
struct i2c_msg *pmsg;
int rc = 0, completed = 0, i;
struct i2c_pnx_algo_data *alg_data = adap->algo_data;
+ unsigned long time_left;
u32 stat;
dev_dbg(&alg_data->adapter.dev,
@@ -548,7 +517,6 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
dev_dbg(&alg_data->adapter.dev, "%s(): mode %d, %d bytes\n",
__func__, alg_data->mif.mode, alg_data->mif.len);
- i2c_pnx_arm_timer(alg_data);
/* initialize the completion var */
init_completion(&alg_data->mif.complete);
@@ -564,7 +532,10 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
break;
/* Wait for completion */
- wait_for_completion(&alg_data->mif.complete);
+ time_left = wait_for_completion_timeout(&alg_data->mif.complete,
+ alg_data->timeout);
+ if (time_left == 0)
+ i2c_pnx_timeout(alg_data);
if (!(rc = alg_data->mif.ret))
completed++;
@@ -653,7 +624,10 @@ static int i2c_pnx_probe(struct platform_device *pdev)
alg_data->adapter.algo_data = alg_data;
alg_data->adapter.nr = pdev->id;
- alg_data->timeout = I2C_PNX_TIMEOUT_DEFAULT;
+ alg_data->timeout = msecs_to_jiffies(I2C_PNX_TIMEOUT_DEFAULT);
+ if (alg_data->timeout <= 1)
+ alg_data->timeout = 2;
+
#ifdef CONFIG_OF
alg_data->adapter.dev.of_node = of_node_get(pdev->dev.of_node);
if (pdev->dev.of_node) {
@@ -673,8 +647,6 @@ static int i2c_pnx_probe(struct platform_device *pdev)
if (IS_ERR(alg_data->clk))
return PTR_ERR(alg_data->clk);
- timer_setup(&alg_data->mif.timer, i2c_pnx_timeout, 0);
-
snprintf(alg_data->adapter.name, sizeof(alg_data->adapter.name),
"%s", pdev->name);
--
2.25.1
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