Patch "i2c-eg20t: fix race between i2c init and interrupt enable" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

i2c-eg20t: fix race between i2c init and interrupt enable

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
i2c-eg20t-fix-race-between-i2c-init-and-interrupt-enable.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Yadi.hu" <[email protected]>
Date: Sun, 18 Sep 2016 18:52:31 +0800
Subject: i2c-eg20t: fix race between i2c init and interrupt enable

From: Yadi.hu <[email protected]>

commit 371a015344b6e270e7e3632107d9554ec6d27a6b upstream.

the eg20t driver call request_irq() function before the pch_base_address, base address of i2c controller's register, is assigned an effective value.

there is one possible scenario that an interrupt which isn't inside eg20t arrives immediately after request_irq() is executed when i2c controller shares an interrupt number with others. since the interrupt handler pch_i2c_handler() has already active as shared action, it will be called and read its own register to determine if this interrupt is from itself.

At that moment, since base address of i2c registers is not remapped in kernel space yet,so the INT handler will access an illegal address and then a error occurs.

---
 drivers/i2c/busses/i2c-eg20t.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

@@ -773,13 +773,6 @@ static int pch_i2c_probe(struct pci_dev
 	/* Set the number of I2C channel instance */
 	adap_info->ch_num = id->driver_data;
 
-	ret = request_irq(pdev->irq, pch_i2c_handler, IRQF_SHARED,
-		  KBUILD_MODNAME, adap_info);
-	if (ret) {
-		pch_pci_err(pdev, "request_irq FAILED\n");
-		goto err_request_irq;
-	}
-
 	for (i = 0; i < adap_info->ch_num; i++) {
 		pch_adap = &adap_info->pch_data[i].pch_adapter;
 		adap_info->pch_i2c_suspended = false;

@@ -796,6 +789,17 @@ static int pch_i2c_probe(struct pci_dev
 		adap_info->pch_data[i].pch_base_address = base_addr + 0x100 * i;
 
 		pch_adap->dev.parent = &pdev->dev;
+	}
+
+	ret = request_irq(pdev->irq, pch_i2c_handler, IRQF_SHARED,
+		  KBUILD_MODNAME, adap_info);
+	if (ret) {
+		pch_pci_err(pdev, "request_irq FAILED\n");
+		goto err_request_irq;
+	}
+
+	for (i = 0; i < adap_info->ch_num; i++) {
+		pch_adap = &adap_info->pch_data[i].pch_adapter;
 
 		pch_i2c_init(&adap_info->pch_data[i]);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/i2c-eg20t-fix-race-between-i2c-init-and-interrupt-enable.patch