| Message ID | 20180624220845.6726-8-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 25 Jun 2018, Sebastian Andrzej Siewior wrote: > The USB completion callback does not disable interrupts while acquiring > the lock. We want to remove the local_irq_disable() invocation from > __usb_hcd_giveback_urb() and therefore it is required for the callback > handler to disable the interrupts while acquiring the lock. > The callback may be invoked either in IRQ or BH context depending on the > USB host controller. > Use the _irqsave() variant of the locking primitives. > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > drivers/usb/misc/usbtest.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c > index 9e1142b8b91b..3b56fb34906c 100644 > --- a/drivers/usb/misc/usbtest.c > +++ b/drivers/usb/misc/usbtest.c > @@ -1082,11 +1082,12 @@ static void ctrl_complete(struct urb *urb) > struct usb_ctrlrequest *reqp; > struct subcase *subcase; > int status = urb->status; > + unsigned long flags; > > reqp = (struct usb_ctrlrequest *)urb->setup_packet; > subcase = container_of(reqp, struct subcase, setup); > > - spin_lock(&ctx->lock); > + spin_lock_irqsave(&ctx->lock, flags); > ctx->count--; > ctx->pending--; > > @@ -1152,9 +1153,9 @@ static void ctrl_complete(struct urb *urb) > > if (u == urb || !u->dev) > continue; > - spin_unlock(&ctx->lock); > + spin_unlock_irqrestore(&ctx->lock, flags); > status = usb_unlink_urb(u); > - spin_lock(&ctx->lock); > + spin_lock_irqsave(&ctx->lock, flags); My feeling tends to be that when a lock is temporarily dropped to take a single action like this, there's no need to restore the interrupt-enable flag. These two calls can remain spin_unlock()/spin_lock(). Aside from this: Acked-by: Alan Stern <stern@rowland.harvard.edu> Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2018-06-25 11:15:06 [-0400], Alan Stern wrote: > > @@ -1152,9 +1153,9 @@ static void ctrl_complete(struct urb *urb) > > > > if (u == urb || !u->dev) > > continue; > > - spin_unlock(&ctx->lock); > > + spin_unlock_irqrestore(&ctx->lock, flags); > > status = usb_unlink_urb(u); > > - spin_lock(&ctx->lock); > > + spin_lock_irqsave(&ctx->lock, flags); > > My feeling tends to be that when a lock is temporarily dropped to take > a single action like this, there's no need to restore the > interrupt-enable flag. These two calls can remain > spin_unlock()/spin_lock(). okay, let me redo this part. > Aside from this: > > Acked-by: Alan Stern <stern@rowland.harvard.edu> > > Alan Stern Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c index 9e1142b8b91b..3b56fb34906c 100644 --- a/drivers/usb/misc/usbtest.c +++ b/drivers/usb/misc/usbtest.c @@ -1082,11 +1082,12 @@ static void ctrl_complete(struct urb *urb) struct usb_ctrlrequest *reqp; struct subcase *subcase; int status = urb->status; + unsigned long flags; reqp = (struct usb_ctrlrequest *)urb->setup_packet; subcase = container_of(reqp, struct subcase, setup); - spin_lock(&ctx->lock); + spin_lock_irqsave(&ctx->lock, flags); ctx->count--; ctx->pending--; @@ -1152,9 +1153,9 @@ static void ctrl_complete(struct urb *urb) if (u == urb || !u->dev) continue; - spin_unlock(&ctx->lock); + spin_unlock_irqrestore(&ctx->lock, flags); status = usb_unlink_urb(u); - spin_lock(&ctx->lock); + spin_lock_irqsave(&ctx->lock, flags); switch (status) { case -EINPROGRESS: case -EBUSY: @@ -1185,7 +1186,7 @@ static void ctrl_complete(struct urb *urb) /* signal completion when nothing's queued */ if (ctx->pending == 0) complete(&ctx->complete); - spin_unlock(&ctx->lock); + spin_unlock_irqrestore(&ctx->lock, flags); } static int @@ -1917,8 +1918,9 @@ struct transfer_context { static void complicated_callback(struct urb *urb) { struct transfer_context *ctx = urb->context; + unsigned long flags; - spin_lock(&ctx->lock); + spin_lock_irqsave(&ctx->lock, flags); ctx->count--; ctx->packet_count += urb->number_of_packets; @@ -1958,7 +1960,7 @@ static void complicated_callback(struct urb *urb) complete(&ctx->done); } done: - spin_unlock(&ctx->lock); + spin_unlock_irqrestore(&ctx->lock, flags); } static struct urb *iso_alloc_urb(
The USB completion callback does not disable interrupts while acquiring the lock. We want to remove the local_irq_disable() invocation from __usb_hcd_giveback_urb() and therefore it is required for the callback handler to disable the interrupts while acquiring the lock. The callback may be invoked either in IRQ or BH context depending on the USB host controller. Use the _irqsave() variant of the locking primitives. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/usb/misc/usbtest.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)