Commit 8219ab4c authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: ehci: drop workaround for forced irq threading 



Force-threaded interrupt handlers used to run with interrupts enabled,
something which could lead to deadlocks in case a threaded handler
shared a lock with code running in hard interrupt context (e.g. timer
callbacks) and did not explicitly disable interrupts.

Since commit 81e2073c ("genirq: Disable interrupts for force
threaded handlers") interrupt handlers always run with interrupts
disabled on non-RT so that drivers no longer need to do handle forced
threading ("threadirqs").

Drop the now obsolete workaround added by commit a1227f3c ("usb:
ehci: fix deadlock when threadirqs option is used").

Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210322111249.32141-1-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0b982876

drivers/usb/host/ehci-hcd.c

+3 −10
Original line number Diff line number Diff line
@@ -705,15 +705,8 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd) 
	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);

	u32			status, masked_status, pcd_status = 0, cmd;

	int			bh;

	unsigned long		flags;



	/*

	 * For threadirqs option we use spin_lock_irqsave() variant to prevent

	 * deadlock with ehci hrtimer callback, because hrtimer callbacks run

	 * in interrupt context even when threadirqs is specified. We can go

	 * back to spin_lock() variant when hrtimer callbacks become threaded.

	 */

	spin_lock_irqsave(&ehci->lock, flags);

	spin_lock(&ehci->lock);



	status = ehci_readl(ehci, &ehci->regs->status);
@@ -731,7 +724,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd) 


	/* Shared IRQ? */

	if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) {

		spin_unlock_irqrestore(&ehci->lock, flags);

		spin_unlock(&ehci->lock);

		return IRQ_NONE;

	}
@@ -842,7 +835,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd) 


	if (bh)

		ehci_work (ehci);

	spin_unlock_irqrestore(&ehci->lock, flags);

	spin_unlock(&ehci->lock);

	if (pcd_status)

		usb_hcd_poll_rh_status(hcd);

	return IRQ_HANDLED;