FAILED: patch "[PATCH] usb: gadget: at91_udc: drain polled-VBUS timer/work before" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] usb: gadget: at91_udc: drain polled-VBUS timer/work before" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x c27d13ce4bab80fbdf6523928071b6c24b37606c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090318-hummus-copier-f77f@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c27d13ce4bab80fbdf6523928071b6c24b37606c Mon Sep 17 00:00:00 2001
From: Fan Wu <fanwu01@zju.edu.cn>
Date: Sun, 19 Jul 2026 04:28:39 +0000
Subject: [PATCH] usb: gadget: at91_udc: drain polled-VBUS timer/work before
 udc is freed

In polled-VBUS mode (board.vbus_pin && board.vbus_polled), probe arms a
self-restarting cycle: at91_vbus_timer() schedules vbus_timer_work, and
at91_vbus_timer_work() calls at91_vbus_update() and re-arms the timer via
mod_timer(). Both recover the same udc through container_of and dereference
it on every iteration.

Neither teardown path cancels this cycle. udc is devm-allocated, so it is
freed after at91udc_remove() returns, and is likewise freed when probe
fails and devres runs. A timer callback or work item that is pending or
running at either point dereferences the freed udc.

Add at91_udc_shutdown_vbus_timer() and call it from at91udc_remove() and
from the usb_add_gadget_udc() failure path in probe; the remaining probe
error paths fail before the timer is armed. timer_shutdown_sync() waits
for a running callback and clears timer->function, which makes the work
handler's mod_timer() a permanent no-op; cancel_work_sync() then drains
any pending or running work whose re-arm attempt now does nothing. The
timer must be shut down first, since cancelling the work alone would let
the timer re-queue it. The guard mirrors probe: in IRQ mode the timer and
work_struct are never initialized.

This does not require a fault; a normal driver unbind can interleave with
an already queued work item.

This issue was found by an in-house static analysis tool.

Fixes: 4037242c4f5f ("ARM: 6209/3: at91_udc: Add vbus polarity and polling mode")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Link: https://patch.msgid.link/20260719042839.3167094-1-fanwu01@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/udc/at91_udc.c b/drivers/usb/gadget/udc/at91_udc.c
index 5aa360ba4f03..8e5d7fb71549 100644
--- a/drivers/usb/gadget/udc/at91_udc.c
+++ b/drivers/usb/gadget/udc/at91_udc.c
@@ -1794,6 +1794,19 @@ static void at91udc_of_init(struct at91_udc *udc, struct device_node *np)
 		udc->caps = match->data;
 }
 
+/*
+ * The work handler re-arms this timer, so shut the timer down before
+ * draining the work; otherwise it restarts the polling cycle.
+ */
+static void at91_udc_shutdown_vbus_timer(struct at91_udc *udc)
+{
+	if (!(udc->board.vbus_pin && udc->board.vbus_polled))
+		return;
+
+	timer_shutdown_sync(&udc->vbus_timer);
+	cancel_work_sync(&udc->vbus_timer_work);
+}
+
 static int at91udc_probe(struct platform_device *pdev)
 {
 	struct device	*dev = &pdev->dev;
@@ -1907,7 +1920,7 @@ static int at91udc_probe(struct platform_device *pdev)
 	}
 	retval = usb_add_gadget_udc(dev, &udc->gadget);
 	if (retval)
-		goto err_unprepare_iclk;
+		goto err_shutdown_vbus;
 	dev_set_drvdata(dev, udc);
 	device_init_wakeup(dev, 1);
 	create_debug_file(udc);
@@ -1915,6 +1928,8 @@ static int at91udc_probe(struct platform_device *pdev)
 	INFO("%s version %s\n", driver_name, DRIVER_VERSION);
 	return 0;
 
+err_shutdown_vbus:
+	at91_udc_shutdown_vbus_timer(udc);
 err_unprepare_iclk:
 	clk_unprepare(udc->iclk);
 err_unprepare_fclk:
@@ -1933,6 +1948,9 @@ static void at91udc_remove(struct platform_device *pdev)
 	DBG("remove\n");
 
 	usb_del_gadget_udc(&udc->gadget);
+
+	at91_udc_shutdown_vbus_timer(udc);
+
 	if (udc->driver) {
 		dev_err(&pdev->dev,
 			"Driver still in use but removing anyhow\n");

[PATCH 6.1.y 1/2] usb: gadget: at91_udc: Convert to platform remove callback returning void

[Sasha Levin]

From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

[ Upstream commit cbd1b152519a581bfe14fb6b14ea6e57cca426c1 ]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

In the error path emit an error message replacing the (less useful)
message by the core. Apart from the improved error message there is no
change in behaviour.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231120215830.71071-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: c27d13ce4bab ("usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/gadget/udc/at91_udc.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/gadget/udc/at91_udc.c b/drivers/usb/gadget/udc/at91_udc.c
index a9a7b3fc60ec9..96d0aabe3c85e 100644
--- a/drivers/usb/gadget/udc/at91_udc.c
+++ b/drivers/usb/gadget/udc/at91_udc.c
@@ -1927,7 +1927,7 @@ static int at91udc_probe(struct platform_device *pdev)
 	return retval;
 }
 
-static int at91udc_remove(struct platform_device *pdev)
+static void at91udc_remove(struct platform_device *pdev)
 {
 	struct at91_udc *udc = platform_get_drvdata(pdev);
 	unsigned long	flags;
@@ -1935,8 +1935,11 @@ static int at91udc_remove(struct platform_device *pdev)
 	DBG("remove\n");
 
 	usb_del_gadget_udc(&udc->gadget);
-	if (udc->driver)
-		return -EBUSY;
+	if (udc->driver) {
+		dev_err(&pdev->dev,
+			"Driver still in use but removing anyhow\n");
+		return;
+	}
 
 	spin_lock_irqsave(&udc->lock, flags);
 	pullup(udc, 0);
@@ -1946,8 +1949,6 @@ static int at91udc_remove(struct platform_device *pdev)
 	remove_debug_file(udc);
 	clk_unprepare(udc->fclk);
 	clk_unprepare(udc->iclk);
-
-	return 0;
 }
 
 #ifdef CONFIG_PM
@@ -2003,7 +2004,7 @@ static int at91udc_resume(struct platform_device *pdev)
 #endif
 
 static struct platform_driver at91_udc_driver = {
-	.remove		= at91udc_remove,
+	.remove_new	= at91udc_remove,
 	.shutdown	= at91udc_shutdown,
 	.suspend	= at91udc_suspend,
 	.resume		= at91udc_resume,
-- 
2.53.0

[PATCH 6.1.y 2/2] usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed

[Sasha Levin]

From: Fan Wu <fanwu01@zju.edu.cn>

[ Upstream commit c27d13ce4bab80fbdf6523928071b6c24b37606c ]

In polled-VBUS mode (board.vbus_pin && board.vbus_polled), probe arms a
self-restarting cycle: at91_vbus_timer() schedules vbus_timer_work, and
at91_vbus_timer_work() calls at91_vbus_update() and re-arms the timer via
mod_timer(). Both recover the same udc through container_of and dereference
it on every iteration.

Neither teardown path cancels this cycle. udc is devm-allocated, so it is
freed after at91udc_remove() returns, and is likewise freed when probe
fails and devres runs. A timer callback or work item that is pending or
running at either point dereferences the freed udc.

Add at91_udc_shutdown_vbus_timer() and call it from at91udc_remove() and
from the usb_add_gadget_udc() failure path in probe; the remaining probe
error paths fail before the timer is armed. timer_shutdown_sync() waits
for a running callback and clears timer->function, which makes the work
handler's mod_timer() a permanent no-op; cancel_work_sync() then drains
any pending or running work whose re-arm attempt now does nothing. The
timer must be shut down first, since cancelling the work alone would let
the timer re-queue it. The guard mirrors probe: in IRQ mode the timer and
work_struct are never initialized.

This does not require a fault; a normal driver unbind can interleave with
an already queued work item.

This issue was found by an in-house static analysis tool.

Fixes: 4037242c4f5f ("ARM: 6209/3: at91_udc: Add vbus polarity and polling mode")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Link: https://patch.msgid.link/20260719042839.3167094-1-fanwu01@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/gadget/udc/at91_udc.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/at91_udc.c b/drivers/usb/gadget/udc/at91_udc.c
index 96d0aabe3c85e..2d55454e61150 100644
--- a/drivers/usb/gadget/udc/at91_udc.c
+++ b/drivers/usb/gadget/udc/at91_udc.c
@@ -1796,6 +1796,19 @@ static void at91udc_of_init(struct at91_udc *udc, struct device_node *np)
 		udc->caps = match->data;
 }
 
+/*
+ * The work handler re-arms this timer, so shut the timer down before
+ * draining the work; otherwise it restarts the polling cycle.
+ */
+static void at91_udc_shutdown_vbus_timer(struct at91_udc *udc)
+{
+	if (!(udc->board.vbus_pin && udc->board.vbus_polled))
+		return;
+
+	timer_shutdown_sync(&udc->vbus_timer);
+	cancel_work_sync(&udc->vbus_timer_work);
+}
+
 static int at91udc_probe(struct platform_device *pdev)
 {
 	struct device	*dev = &pdev->dev;
@@ -1909,7 +1922,7 @@ static int at91udc_probe(struct platform_device *pdev)
 	}
 	retval = usb_add_gadget_udc(dev, &udc->gadget);
 	if (retval)
-		goto err_unprepare_iclk;
+		goto err_shutdown_vbus;
 	dev_set_drvdata(dev, udc);
 	device_init_wakeup(dev, 1);
 	create_debug_file(udc);
@@ -1917,6 +1930,8 @@ static int at91udc_probe(struct platform_device *pdev)
 	INFO("%s version %s\n", driver_name, DRIVER_VERSION);
 	return 0;
 
+err_shutdown_vbus:
+	at91_udc_shutdown_vbus_timer(udc);
 err_unprepare_iclk:
 	clk_unprepare(udc->iclk);
 err_unprepare_fclk:
@@ -1935,6 +1950,9 @@ static void at91udc_remove(struct platform_device *pdev)
 	DBG("remove\n");
 
 	usb_del_gadget_udc(&udc->gadget);
+
+	at91_udc_shutdown_vbus_timer(udc);
+
 	if (udc->driver) {
 		dev_err(&pdev->dev,
 			"Driver still in use but removing anyhow\n");
-- 
2.53.0