FAILED: patch "[PATCH] comedi: jr3_pci: Fix synchronous deletion of timer" failed to apply to 6.1-stable tree

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 <[email protected]>.

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 44d9b3f584c59a606b521e7274e658d5b866c699
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025042807-emcee-squealing-c022@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 44d9b3f584c59a606b521e7274e658d5b866c699 Mon Sep 17 00:00:00 2001
From: Ian Abbott <[email protected]>
Date: Tue, 15 Apr 2025 13:39:01 +0100
Subject: [PATCH] comedi: jr3_pci: Fix synchronous deletion of timer

When jr3_pci_detach() is called during device removal, it calls timer_delete_sync() to stop the timer, but the timer expiry function always reschedules the timer, so the synchronization is ineffective.

Call timer_shutdown_sync() instead. It does not matter that the timer expiry function pointer is cleared, because the device is being removed.

index cdc842b32bab..75dce1ff2419 100644
@@ -758,7 +758,7 @@ static void jr3_pci_detach(struct comedi_device *dev)
 	struct jr3_pci_dev_private *devpriv = dev->private;
 
 	if (devpriv)
-		timer_delete_sync(&devpriv->timer);
+		timer_shutdown_sync(&devpriv->timer);
 
 	comedi_pci_detach(dev);
 }

commit 44d9b3f584c59a606b521e7274e658d5b866c699 upstream.

When jr3_pci_detach() is called during device removal, it calls timer_delete_sync() to stop the timer, but the timer expiry function always reschedules the timer, so the synchronization is ineffective.

Add a member bool timer_enable to the device private data to indicate whether the timer should be restarted. Use the main comedi device spin-lock for synchronization, as that is already used by the timer expiry function. (The upstream commit called timer_shutdown_sync() instead of timer_delete_sync(), but that is not available.)

---
 drivers/comedi/drivers/jr3_pci.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

index 951c23fa0369..88f1e7862614 100644
@@ -87,6 +87,7 @@ struct jr3_pci_poll_delay {
 struct jr3_pci_dev_private {
 	struct timer_list timer;
 	struct comedi_device *dev;
+	bool timer_enable;
 };
 
 union jr3_pci_single_range {

@@ -596,10 +597,11 @@ static void jr3_pci_poll_dev(struct timer_list *t)
 				delay = sub_delay.max;
 		}
 	}
+	if (devpriv->timer_enable) {
+		devpriv->timer.expires = jiffies + msecs_to_jiffies(delay);
+		add_timer(&devpriv->timer);
+	}
 	spin_unlock_irqrestore(&dev->spinlock, flags);
-
-	devpriv->timer.expires = jiffies + msecs_to_jiffies(delay);
-	add_timer(&devpriv->timer);
 }
 
 static struct jr3_pci_subdev_private *

@@ -748,6 +750,7 @@ static int jr3_pci_auto_attach(struct comedi_device *dev,
 	devpriv->dev = dev;
 	timer_setup(&devpriv->timer, jr3_pci_poll_dev, 0);
 	devpriv->timer.expires = jiffies + msecs_to_jiffies(1000);
+	devpriv->timer_enable = true;
 	add_timer(&devpriv->timer);
 
 	return 0;

@@ -757,8 +760,12 @@ static void jr3_pci_detach(struct comedi_device *dev)
 {
 	struct jr3_pci_dev_private *devpriv = dev->private;
 
-	if (devpriv)
-		del_timer_sync(&devpriv->timer);
+	if (devpriv) {
+		spin_lock_bh(&dev->spinlock);
+		devpriv->timer_enable = false;
+		spin_unlock_bh(&dev->spinlock);
+		timer_delete_sync(&devpriv->timer);
+	}
 
 	comedi_pci_detach(dev);
 }

2.47.2