The current root hub polling code exhibits a spinlock recursion on the
private controller lock. r8a66597_root_hub_control() is called from
r8a66597_timer() which grabs the lock and disables IRQs. The following
chain emerges:
r8a66597_timer() <-- lock taken
r8a66597_root_hub_control()
r8a66597_check_syssts()
usb_hcd_poll_rh_status() <-- acquires the same lock
/* insert death here */
The entire chain requires IRQs to be disabled, so we just unlock and
relock around the call to usb_hcd_poll_rh_status() while leaving the
IRQ state unchanged.
Signed-off-by: Paul Mundt <lethal@xxxxxxxxxxxx>
---
drivers/usb/host/r8a66597-hcd.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/host/r8a66597-hcd.c b/drivers/usb/host/r8a66597-hcd.c
index 0ceec12..bee558a 100644
--- a/drivers/usb/host/r8a66597-hcd.c
+++ b/drivers/usb/host/r8a66597-hcd.c
@@ -1006,6 +1022,8 @@ static void start_root_hub_sampling(struct r8a66597 *r8a66597, int port,
/* this function must be called with interrupt disabled */
static void r8a66597_check_syssts(struct r8a66597 *r8a66597, int port,
u16 syssts)
+__releases(r8a66597->lock)
+__acquires(r8a66597->lock)
{
if (syssts == SE0) {
r8a66597_write(r8a66597, ~ATTCH, get_intsts_reg(port));
@@ -1023,7 +1041,9 @@ static void r8a66597_check_syssts(struct r8a66597 *r8a66597, int port,
usb_hcd_resume_root_hub(r8a66597_to_hcd(r8a66597));
}
+ spin_unlock(&r8a66597->lock);
usb_hcd_poll_rh_status(r8a66597_to_hcd(r8a66597));
+ spin_lock(&r8a66597->lock);
}
/* this function must be called with interrupt disabled */
--
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