Re: [PATCH 1/2] [net/9p] Set the condition just before waking up.

["Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>]

On Mon, 14 Mar 2011 15:12:41 -0700, "Venkateswararao Jujjuri (JV)" <jvrao@linux.vnet.ibm.com> wrote:
> Given that the sprious wake-ups are common, we need to move the
> condition setting right next to the wake_up().

I don't understand the above. What do you mean by spurious wakeups are
common ? I guess what happened was that when the work queue got woken up
via p9_client_cb, another request req->status was found to be received
(REQ_STATUS_RCVD) because we set it ahead. So it is not that spurious
wakeups are common, but rather it is a bug we had right ?

>  After setting the condition
> to req->status = REQ_STATUS_RCVD, sprious wakeups may cause the
> virtqueue back on the free list for someone else to use.
> This may result in kernel panic while relasing the pinned pages
> in p9_release_req_pages().

But why are we doing that release pages in the req_done path. ? why not
after we wake up the sleeper in p9_client_rpc ?

-aneesh