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i2c: altera: Fix race between xfer_msg and isr thread

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Use a mutex to protect access to idev->msg_len, idev->buf, etc. which
are modified by both altr_i2c_xfer_msg() and altr_i2c_isr().

This is the minimal fix for easy backporting. A cleanup to remove the
spinlock will be added later.

Signed-off-by: Atsushi Nemoto <atsushi.nemoto@sord.co.jp>
Acked-by: Thor Thayer <thor.thayer@linux.intel.com>
[wsa: updated commit message]
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Atsushi Nemoto 2020-05-08 22:12:48 +09:00 committed by Wolfram Sang
parent ab7cf7e53c
commit 5d4c797749
1 changed files with 9 additions and 1 deletions
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10
drivers/i2c/busses/i2c-altera.c
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@ -70,6 +70,7 @@
* @isr_mask: cached copy of local ISR enables.
* @isr_status: cached copy of local ISR status.
* @lock: spinlock for IRQ synchronization.
* @isr_mutex: mutex for IRQ thread.
*/
struct altr_i2c_dev {
void __iomem *base;
@ -86,6 +87,7 @@ struct altr_i2c_dev {
u32 isr_mask;
u32 isr_status;
spinlock_t lock; /* IRQ synchronization */
struct mutex isr_mutex;
};
static void
@ -245,10 +247,11 @@ static irqreturn_t altr_i2c_isr(int irq, void *_dev)
struct altr_i2c_dev *idev = _dev;
u32 status = idev->isr_status;
mutex_lock(&idev->isr_mutex);
if (!idev->msg) {
dev_warn(idev->dev, "unexpected interrupt\n");
altr_i2c_int_clear(idev, ALTR_I2C_ALL_IRQ);
return IRQ_HANDLED;
goto out;
}
read = (idev->msg->flags & I2C_M_RD) != 0;
@ -301,6 +304,8 @@ static irqreturn_t altr_i2c_isr(int irq, void *_dev)
complete(&idev->msg_complete);
dev_dbg(idev->dev, "Message Complete\n");
}
out:
mutex_unlock(&idev->isr_mutex);
return IRQ_HANDLED;
}
@ -312,6 +317,7 @@ static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg)
u32 value;
u8 addr = i2c_8bit_addr_from_msg(msg);
mutex_lock(&idev->isr_mutex);
idev->msg = msg;
idev->msg_len = msg->len;
idev->buf = msg->buf;
@ -336,6 +342,7 @@ static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg)
altr_i2c_int_enable(idev, imask, true);
altr_i2c_fill_tx_fifo(idev);
}
mutex_unlock(&idev->isr_mutex);
time_left = wait_for_completion_timeout(&idev->msg_complete,
ALTR_I2C_XFER_TIMEOUT);
@ -409,6 +416,7 @@ static int altr_i2c_probe(struct platform_device *pdev)
idev->dev = &pdev->dev;
init_completion(&idev->msg_complete);
spin_lock_init(&idev->lock);
mutex_init(&idev->isr_mutex);
ret = device_property_read_u32(idev->dev, "fifo-size",
&idev->fifo_size);