linux-kernel - [PATCH v3 1/2] USB: core: Disable remote wakeup for freeze/quiesce

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Message-Id: <20220421103751.v3.1.I2c636c4decc358f5e6c27b810748904cc69beada@changeid>
Date:   Thu, 21 Apr 2022 10:39:26 -0700
From:   Evan Green <evgreen@...omium.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Mathias Nyman <mathias.nyman@...el.com>,
        Alan Stern <stern@...land.harvard.edu>,
        Rajat Jain <rajatja@...omium.org>,
        Oliver Neukum <oneukum@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Evan Green <evgreen@...omium.org>,
        Razvan Heghedus <heghedus.razvan@...il.com>,
        Wei Ming Chen <jj251510319013@...il.com>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: [PATCH v3 1/2] USB: core: Disable remote wakeup for freeze/quiesce

The PM_EVENT_FREEZE and PM_EVENT_QUIESCE messages should cause the
device to stop generating interrupts. USB core was previously allowing
devices that were already runtime suspended to keep remote wakeup
enabled if they had gone down that way. This violates the contract with
pm, and can potentially cause MSI interrupts to be lost.

Change that so that if a device is runtime suspended with remote wakeups
enabled, it will be resumed to ensure remote wakeup is always disabled
across a freeze.

Signed-off-by: Evan Green <evgreen@...omium.org>
Acked-by: Alan Stern <stern@...land.harvard.edu>

---

Changes in v3:
 - Fix comment formatting and line wrap

Changes in v2:
 - Introduced the patch to always disable remote wakeups

 drivers/usb/core/driver.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 355ed33a21792b..b87452e228353d 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1533,22 +1533,23 @@ static void choose_wakeup(struct usb_device *udev, pm_message_t msg)
 {
 	int	w;
 
-	/* Remote wakeup is needed only when we actually go to sleep.
-	 * For things like FREEZE and QUIESCE, if the device is already
-	 * autosuspended then its current wakeup setting is okay.
+	/*
+	 * For FREEZE/QUIESCE, disable remote wakeups so no interrupts get
+	 * generated.
 	 */
 	if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_QUIESCE) {
-		if (udev->state != USB_STATE_SUSPENDED)
-			udev->do_remote_wakeup = 0;
-		return;
-	}
+		w = 0;
 
-	/* Enable remote wakeup if it is allowed, even if no interface drivers
-	 * actually want it.
-	 */
-	w = device_may_wakeup(&udev->dev);
+	} else {
+		/*
+		 * Enable remote wakeup if it is allowed, even if no interface
+		 * drivers actually want it.
+		 */
+		w = device_may_wakeup(&udev->dev);
+	}
 
-	/* If the device is autosuspended with the wrong wakeup setting,
+	/*
+	 * If the device is autosuspended with the wrong wakeup setting,
 	 * autoresume now so the setting can be changed.
 	 */
 	if (udev->state == USB_STATE_SUSPENDED && w != udev->do_remote_wakeup)
-- 
2.31.0