Re: [PATCHv2 1/3] eventfd: allow atomic read and waitqueue remove
From: Avi Kivity
Date: Thu Jan 21 2010 - 12:57:33 EST
On 01/21/2010 07:56 PM, Avi Kivity wrote:
On 01/21/2010 07:45 PM, Michael S. Tsirkin wrote:
But you're in process context. An eventfd never blocks.
Yes it blocks if counter is 0. And we don't know
it's not 0 unless we read :) catch-22.
Ah yes, I forgot.
Well, you can poll it and then read it... this introduces a new race (if
userspace does a read in parallel) but it's limited to kvm and buggy
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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