This patch (as1589) resolves some unlikely races involving system
shutdown or controller death in ehci-hcd:
Shutdown races with both root-hub resume and controller
resume.
Controller death races with root-hub suspend.
A new bitflag is added to indicate that the controller has been shut
down (whether for system shutdown or because it died). Tests are
added in the suspend and resume pathways to avoid reactivating the
controller after any sort of shutdown.
Signed-off-by: Alan Stern <st...@rowland.harvard.edu>
---
drivers/usb/host/ehci-hcd.c | 20 +++++++++++++++++++-
drivers/usb/host/ehci-hub.c | 27 +++++++++++++++++++++++----
drivers/usb/host/ehci.h | 1 +
3 files changed, 43 insertions(+), 5 deletions(-)
Index: usb-3.4/drivers/usb/host/ehci.h
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci.h
+++ usb-3.4/drivers/usb/host/ehci.h
@@ -118,6 +118,7 @@ struct ehci_hcd { /* one per controlle
bool need_rescan:1;
bool intr_unlinking:1;
bool async_unlinking:1;
+ bool shutdown:1;
struct ehci_qh *qh_scan_next;
/* async schedule support */
Index: usb-3.4/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci-hcd.c
+++ usb-3.4/drivers/usb/host/ehci-hcd.c
@@ -343,6 +343,7 @@ static void ehci_shutdown(struct usb_hcd
struct ehci_hcd *ehci = hcd_to_ehci(hcd);
spin_lock_irq(&ehci->lock);
+ ehci->shutdown = true;
ehci->rh_state = EHCI_RH_STOPPING;
ehci->enabled_hrtimer_events = 0;
spin_unlock_irq(&ehci->lock);
@@ -823,6 +824,7 @@ dead:
usb_hc_died(hcd);
/* Don't let the controller do anything more */
+ ehci->shutdown = true;
ehci->rh_state = EHCI_RH_STOPPING;
ehci->command &= ~(CMD_RUN | CMD_ASE | CMD_PSE);
ehci_writel(ehci, ehci->command, &ehci->regs->command);
@@ -1129,6 +1131,9 @@ static int __maybe_unused ehci_resume(st
/* Mark hardware accessible again as we are back to full power by now */
set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
+ if (ehci->shutdown)
+ return 0; /* Controller is dead */
+
/*
* If CF is still set and we aren't resuming from hibernation
* then we maintained suspend power.
@@ -1139,10 +1144,17 @@ static int __maybe_unused ehci_resume(st
int mask = INTR_MASK;
ehci_prepare_ports_for_controller_resume(ehci);
+
+ spin_lock_irq(&ehci->lock);
+ if (ehci->shutdown)
+ goto skip;
+
if (!hcd->self.root_hub->do_remote_wakeup)
mask &= ~STS_PCD;
ehci_writel(ehci, mask, &ehci->regs->intr_enable);
ehci_readl(ehci, &ehci->regs->intr_enable);
+ skip:
+ spin_unlock_irq(&ehci->lock);
return 0;
}
@@ -1154,14 +1166,20 @@ static int __maybe_unused ehci_resume(st
(void) ehci_halt(ehci);
(void) ehci_reset(ehci);
+ spin_lock_irq(&ehci->lock);
+ if (ehci->shutdown)
+ goto skip;
+
ehci_writel(ehci, ehci->command, &ehci->regs->command);
ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag);
ehci_readl(ehci, &ehci->regs->command); /* unblock posted writes */
+ ehci->rh_state = EHCI_RH_SUSPENDED;
+ spin_unlock_irq(&ehci->lock);
+
/* here we "know" root ports should always stay powered */
ehci_port_power(ehci, 1);
- ehci->rh_state = EHCI_RH_SUSPENDED;
return 1;
}
Index: usb-3.4/drivers/usb/host/ehci-hub.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci-hub.c
+++ usb-3.4/drivers/usb/host/ehci-hub.c
@@ -221,6 +221,8 @@ static int ehci_bus_suspend (struct usb_
ehci_quiesce(ehci);
spin_lock_irq (&ehci->lock);
+ if (ehci->rh_state < EHCI_RH_RUNNING)
+ goto done;
/* Once the controller is stopped, port resumes that are already
* in progress won't complete. Hence if remote wakeup is enabled
@@ -306,6 +308,10 @@ static int ehci_bus_suspend (struct usb_
ehci_halt (ehci);
spin_lock_irq(&ehci->lock);
+ if (ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_POLL_DEAD))
+ ehci_handle_controller_death(ehci);
+ if (ehci->rh_state != EHCI_RH_RUNNING)
+ goto done;
ehci->rh_state = EHCI_RH_SUSPENDED;
end_unlink_async(ehci);
@@ -320,6 +326,7 @@ static int ehci_bus_suspend (struct usb_
ehci_writel(ehci, mask, &ehci->regs->intr_enable);
ehci_readl(ehci, &ehci->regs->intr_enable);
+ done:
ehci->next_statechange = jiffies + msecs_to_jiffies(10);
ehci->enabled_hrtimer_events = 0;
ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
@@ -342,10 +349,8 @@ static int ehci_bus_resume (struct usb_h
if (time_before (jiffies, ehci->next_statechange))
msleep(5);
spin_lock_irq (&ehci->lock);
- if (!HCD_HW_ACCESSIBLE(hcd)) {
- spin_unlock_irq(&ehci->lock);
- return -ESHUTDOWN;
- }
+ if (!HCD_HW_ACCESSIBLE(hcd) || ehci->shutdown)
+ goto shutdown;
if (unlikely(ehci->debug)) {
if (!dbgp_reset_prep())
@@ -384,6 +389,8 @@ static int ehci_bus_resume (struct usb_h
spin_unlock_irq(&ehci->lock);
msleep(8);
spin_lock_irq(&ehci->lock);
+ if (ehci->shutdown)
+ goto shutdown;
/* clear phy low-power mode before resume */
if (ehci->bus_suspended && ehci->has_hostpc) {
@@ -401,6 +408,8 @@ static int ehci_bus_resume (struct usb_h
spin_unlock_irq(&ehci->lock);
msleep(5);
spin_lock_irq(&ehci->lock);
+ if (ehci->shutdown)
+ goto shutdown;
}
/* manually resume the ports we suspended during bus_suspend() */
@@ -421,6 +430,8 @@ static int ehci_bus_resume (struct usb_h
spin_unlock_irq(&ehci->lock);
msleep(20);
spin_lock_irq(&ehci->lock);
+ if (ehci->shutdown)
+ goto shutdown;
}
i = HCS_N_PORTS (ehci->hcs_params);
@@ -439,10 +450,18 @@ static int ehci_bus_resume (struct usb_h
ehci_handover_companion_ports(ehci);
/* Now we can safely re-enable irqs */
+ spin_lock_irq(&ehci->lock);
+ if (ehci->shutdown)
+ goto shutdown;
ehci_writel(ehci, INTR_MASK, &ehci->regs->intr_enable);
(void) ehci_readl(ehci, &ehci->regs->intr_enable);
+ spin_unlock_irq(&ehci->lock);
return 0;
+
+ shutdown:
+ spin_unlock_irq(&ehci->lock);
+ return -ESHUTDOWN;
}
#else
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