Messages in this thread | | | Date | Tue, 3 Oct 2006 14:03:12 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH 3/3] IRQ: Maintain regs pointer globally rather than passing to IRQ handlers |
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[Most people removed from CC: since they probably aren't too interested in this.]
On Mon, 2 Oct 2006, David Brownell wrote:
> On Monday 02 October 2006 2:34 pm, Alan Stern wrote: > > On Mon, 2 Oct 2006, David Brownell wrote: > > > > > > > (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does > > > > > something different depending on whether it's been supplied with a regs > > > > > pointer or not. > > > > > > gaak! where did that come from? I'll be surprised if removing > > > that causes any problem at all. > > > > Here's the statement in question: > > > > if (likely (regs && HC_IS_RUNNING(ohci_to_hcd(ohci)->state))) { > > Where as I said, removing the "regs &&" should be just fine. > (Is the plan that David Howells re-issue that patch? If so, I'l > expect e will just fix it that way...) > > > ... > > > > Notice another questionable use of hcd->state. > > Questionable in what way? When that code is called to clean up > after driver death, that loop must be ignored ... every pending I/O > can safely be scrubbed. That's the main point of that particular > HC_IS_RUNNING() test. In other cases, it's essential not to touch > DMA queue entries that the host controller is still using.
Questionable because changes to hcd->state aren't synchronized with the driver. In this case it probably doesn't end up making any difference.
Removing "regs &&" might change other aspects too. For instance, does this routine ever get called from a timer routine, where regs would normally be NULL? In such situations removing "regs &&" would reverse the sense of the test.
Alan Stern
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