USB: OHCI: make URB completions single-threaded
URBs for a particular endpoint should complete sequentially. That is,
we shouldn't call the completion handler for one URB until the handler
for the previous URB has returned.
When the OHCI watchdog routine is added, there will be two paths for
completing URBs: interrupt handler and watchdog routine. Their
activities have to be synchronized so that completions don't occur in
multiple threads concurrently.
For that purpose, this patch creates an ohci_work() routine which will
be responsible for calling process_done_list() and finish_unlinks(),
the two routines that detect when an URB is complete. Everything will
funnel through ohci_work(), and it will be careful not to run in more
than one thread at a time.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 3112799..ad58853 100644
--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -316,7 +316,7 @@
if (ohci->rh_state != OHCI_RH_RUNNING) {
/* With HC dead, we can clean up right away */
- finish_unlinks(ohci, 0);
+ ohci_work(ohci);
}
}
spin_unlock_irqrestore (&ohci->lock, flags);
@@ -349,7 +349,7 @@
if (ohci->rh_state != OHCI_RH_RUNNING) {
sanitize:
ed->state = ED_IDLE;
- finish_unlinks (ohci, 0);
+ ohci_work(ohci);
}
switch (ed->state) {
@@ -789,9 +789,7 @@
/* handle any pending URB/ED unlinks, leaving INTR_SF enabled
* when there's still unlinking to be done (next frame).
*/
- process_done_list(ohci);
- if (ohci->ed_rm_list)
- finish_unlinks (ohci, ohci_frame_no(ohci));
+ ohci_work(ohci);
if ((ints & OHCI_INTR_SF) != 0 && !ohci->ed_rm_list
&& ohci->rh_state == OHCI_RH_RUNNING)
ohci_writel (ohci, OHCI_INTR_SF, ®s->intrdisable);
@@ -879,7 +877,7 @@
if (!urb->unlinked)
urb->unlinked = -ESHUTDOWN;
}
- finish_unlinks (ohci, 0);
+ ohci_work(ohci);
spin_unlock_irq(&ohci->lock);
/* paranoia, in case that didn't work: */
diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c
index dccb90e..8991692 100644
--- a/drivers/usb/host/ohci-hub.c
+++ b/drivers/usb/host/ohci-hub.c
@@ -40,8 +40,7 @@
(OHCI_CTRL_CLE|OHCI_CTRL_BLE|OHCI_CTRL_PLE|OHCI_CTRL_IE)
static void update_done_list(struct ohci_hcd *);
-static void process_done_list(struct ohci_hcd *);
-static void finish_unlinks (struct ohci_hcd *, u16);
+static void ohci_work(struct ohci_hcd *);
#ifdef CONFIG_PM
static int ohci_rh_suspend (struct ohci_hcd *ohci, int autostop)
@@ -89,8 +88,7 @@
spin_lock_irq (&ohci->lock);
}
update_done_list(ohci);
- process_done_list(ohci);
- finish_unlinks (ohci, ohci_frame_no(ohci));
+ ohci_work(ohci);
/*
* Some controllers don't handle "global" suspend properly if
diff --git a/drivers/usb/host/ohci-q.c b/drivers/usb/host/ohci-q.c
index f36b2fa..1974ddc 100644
--- a/drivers/usb/host/ohci-q.c
+++ b/drivers/usb/host/ohci-q.c
@@ -964,9 +964,9 @@
/*-------------------------------------------------------------------------*/
/* there are some urbs/eds to unlink; called in_irq(), with HCD locked */
-static void
-finish_unlinks (struct ohci_hcd *ohci, u16 tick)
+static void finish_unlinks(struct ohci_hcd *ohci)
{
+ unsigned tick = ohci_frame_no(ohci);
struct ed *ed, **last;
rescan_all:
@@ -1202,3 +1202,27 @@
takeback_td(ohci, td);
}
}
+
+/*
+ * TD takeback and URB giveback must be single-threaded.
+ * This routine takes care of it all.
+ */
+static void ohci_work(struct ohci_hcd *ohci)
+{
+ if (ohci->working) {
+ ohci->restart_work = 1;
+ return;
+ }
+ ohci->working = 1;
+
+ restart:
+ process_done_list(ohci);
+ if (ohci->ed_rm_list)
+ finish_unlinks(ohci);
+
+ if (ohci->restart_work) {
+ ohci->restart_work = 0;
+ goto restart;
+ }
+ ohci->working = 0;
+}
diff --git a/drivers/usb/host/ohci.h b/drivers/usb/host/ohci.h
index a8259bc..ef348c2 100644
--- a/drivers/usb/host/ohci.h
+++ b/drivers/usb/host/ohci.h
@@ -393,6 +393,8 @@
unsigned long next_statechange; /* suspend/resume */
u32 fminterval; /* saved register */
unsigned autostop:1; /* rh auto stopping/stopped */
+ unsigned working:1;
+ unsigned restart_work:1;
unsigned long flags; /* for HC bugs */
#define OHCI_QUIRK_AMD756 0x01 /* erratum #4 */