[PATCH v1] usb: dwc3: gadget: Prevent irq storm when TH re-executes
From: Badhri Jagan Sridharan
Date: Fri Jan 24 2025 - 02:59:34 EST
While commit d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events
in event cache") makes sure that top half(TH) does not end up overwriting
the cached events before processing them when the TH gets invoked more
than one time, returning IRQ_HANDLED results in occasional irq storm
where the TH hogs the CPU. The irq storm can be prevented if
IRQ_WAKE_THREAD is returned.
ftrace event stub during dwc3 irq storm:
irq/504_dwc3-1111 ( 1111) [000] .... 70.000866: irq_handler_exit: irq=14 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000872: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000874: irq_handler_exit: irq=504 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000881: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000883: irq_handler_exit: irq=504 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000889: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000892: irq_handler_exit: irq=504 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000898: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000901: irq_handler_exit: irq=504 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000907: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000909: irq_handler_exit: irq=504 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000915: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000918: irq_handler_exit: irq=504 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000924: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000927: irq_handler_exit: irq=504 ret=handled
irq/504_dwc3-1111 ( 1111) [000] .... 70.000933: irq_handler_entry: irq=504 name=dwc3
irq/504_dwc3-1111 ( 1111) [000] .... 70.000935: irq_handler_exit: irq=504 ret=handled
....
Cc: stable@xxxxxxxxxx
Fixes: d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events in event cache")
Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
---
drivers/usb/dwc3/gadget.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index d27af65eb08a..376ab75adc4e 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4519,7 +4519,7 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
* losing events.
*/
if (evt->flags & DWC3_EVENT_PENDING)
- return IRQ_HANDLED;
+ return IRQ_WAKE_THREAD;
count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
count &= DWC3_GEVNTCOUNT_MASK;
base-commit: 70cd0576aa39c55aabd227851cba0c601e811fb6
--
2.48.1.262.g85cc9f2d1e-goog