From: Ralph Siemsen Date: Tue, 18 Mar 2025 15:09:32 +0000 (-0400) Subject: usb: cdns3: Fix deadlock when using NCM gadget X-Git-Tag: v6.15-rc4~21^2~14 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a1059896f2bfdcebcdc7153c3be2307ea319501f;p=thirdparty%2Fkernel%2Flinux.git usb: cdns3: Fix deadlock when using NCM gadget The cdns3 driver has the same NCM deadlock as fixed in cdnsp by commit 58f2fcb3a845 ("usb: cdnsp: Fix deadlock issue during using NCM gadget"). Under PREEMPT_RT the deadlock can be readily triggered by heavy network traffic, for example using "iperf --bidir" over NCM ethernet link. The deadlock occurs because the threaded interrupt handler gets preempted by a softirq, but both are protected by the same spinlock. Prevent deadlock by disabling softirq during threaded irq handler. Cc: stable Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver") Signed-off-by: Ralph Siemsen Acked-by: Peter Chen Reviewed-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20250318-rfs-cdns3-deadlock-v2-1-bfd9cfcee732@linaro.org Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c index 694aa14577390..d9d8dc05b2359 100644 --- a/drivers/usb/cdns3/cdns3-gadget.c +++ b/drivers/usb/cdns3/cdns3-gadget.c @@ -1963,6 +1963,7 @@ static irqreturn_t cdns3_device_thread_irq_handler(int irq, void *data) unsigned int bit; unsigned long reg; + local_bh_disable(); spin_lock_irqsave(&priv_dev->lock, flags); reg = readl(&priv_dev->regs->usb_ists); @@ -2004,6 +2005,7 @@ static irqreturn_t cdns3_device_thread_irq_handler(int irq, void *data) irqend: writel(~0, &priv_dev->regs->ep_ien); spin_unlock_irqrestore(&priv_dev->lock, flags); + local_bh_enable(); return ret; }