linux-kernel - [PATCH v2] usb: cdnsp: Fix lack of spin_lock_irqsave/spin_lock

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Date:   Tue, 14 Dec 2021 05:55:27 +0100
From:   Pawel Laszczak <pawell@...ence.com>
To:     <peter.chen@...nel.org>
CC:     <gregkh@...uxfoundation.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <pawell@...ence.com>,
        <jianhe@...arella.com>, <stable@...r.kernel.org>
Subject: [PATCH v2] usb: cdnsp: Fix lack of spin_lock_irqsave/spin_lock_restore

From: Pawel Laszczak <pawell@...ence.com>

Patch puts content of cdnsp_gadget_pullup function inside
spin_lock_irqsave and spin_lock_restore section.
This construction is required here to keep the data consistency,
otherwise some data can be changed e.g. from interrupt context.

Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
Reported-by: Ken (Jian) He <jianhe@...arella.com>
cc: <stable@...r.kernel.org>
Signed-off-by: Pawel Laszczak <pawell@...ence.com>
--

Changelog:
v2:
- added disable_irq/enable_irq as sugester by Peter Chen

 drivers/usb/cdns3/cdnsp-gadget.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/usb/cdns3/cdnsp-gadget.c b/drivers/usb/cdns3/cdnsp-gadget.c
index f6d231760a6a..e07a65b980af 100644
--- a/drivers/usb/cdns3/cdnsp-gadget.c
+++ b/drivers/usb/cdns3/cdnsp-gadget.c
@@ -1544,15 +1544,27 @@ static int cdnsp_gadget_pullup(struct usb_gadget *gadget, int is_on)
 {
 	struct cdnsp_device *pdev = gadget_to_cdnsp(gadget);
 	struct cdns *cdns = dev_get_drvdata(pdev->dev);
+	unsigned long flags;
 
 	trace_cdnsp_pullup(is_on);
 
+	/*
+	 * Disable events handling while controller is being
+	 * enabled/disabled.
+	 */
+	disable_irq(cdns->dev_irq);
+	spin_lock_irqsave(&pdev->lock, flags);
+
 	if (!is_on) {
 		cdnsp_reset_device(pdev);
 		cdns_clear_vbus(cdns);
 	} else {
 		cdns_set_vbus(cdns);
 	}
+
+	spin_unlock_irqrestore(&pdev->lock, flags);
+	enable_irq(cdns->dev_irq);
+
 	return 0;
 }
 
-- 
2.25.1