From cdb4dd15e62eb984d9461b520d15d00ff2b88d9d Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Fri, 18 Jul 2014 16:26:07 -0400 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ohci-hcd.c | 10 ++++------ drivers/usb/host/ohci-hub.c | 6 ++---- drivers/usb/host/ohci-q.c | 28 ++++++++++++++++++++++++++-- drivers/usb/host/ohci.h | 2 ++ 4 files changed, 34 insertions(+), 12 deletions(-) diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c index 3112799bba7f..ad588538e2e7 100644 --- a/drivers/usb/host/ohci-hcd.c +++ b/drivers/usb/host/ohci-hcd.c @@ -316,7 +316,7 @@ static int ohci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) 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 @@ rescan: 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 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd) /* 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 @@ int ohci_restart(struct ohci_hcd *ohci) 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 dccb90edd66e..8991692bcfb8 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 @@ __acquires(ohci->lock) 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 f36b2fa0ee2f..1974ddc68e45 100644 --- a/drivers/usb/host/ohci-q.c +++ b/drivers/usb/host/ohci-q.c @@ -964,9 +964,9 @@ static void update_done_list(struct ohci_hcd *ohci) /*-------------------------------------------------------------------------*/ /* 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 @@ static void process_done_list(struct ohci_hcd *ohci) 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 a8259bc6fd8b..ef348c2e1e4b 100644 --- a/drivers/usb/host/ohci.h +++ b/drivers/usb/host/ohci.h @@ -393,6 +393,8 @@ struct ohci_hcd { 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 */ -- 2.20.1