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Commit 2133e30f authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Greg Kroah-Hartman
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i2c: altera: Fix race between xfer_msg and isr thread 



[ Upstream commit 5d4c7977499a736f3f80826bdc9744344ad55589 ]

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: default avatarAtsushi Nemoto <atsushi.nemoto@sord.co.jp>
Acked-by: default avatarThor Thayer <thor.thayer@linux.intel.com>
[wsa: updated commit message]
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent a0006477

drivers/i2c/busses/i2c-altera.c

+9 −1
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ 
 * @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;
@@ -97,6 +98,7 @@ struct altr_i2c_dev { 
	u32 isr_mask;

	u32 isr_status;

	spinlock_t lock;	/* IRQ synchronization */

	struct mutex isr_mutex;

};



static void
@@ -256,10 +258,11 @@ 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;
@@ -312,6 +315,8 @@ 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;

}
@@ -323,6 +328,7 @@ 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;
@@ -347,6 +353,7 @@ 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);
@@ -420,6 +427,7 @@ 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);