Date: Wed, 07 Apr 2004 02:19:13 +0100 From: Colin Percival <colin.percival@wadham.ox.ac.uk> To: Nate Lawson <nate@root.org> Cc: Colin Percival <colin.percival@wadham.ox.ac.uk> Subject: Re: cvs commit: src/sys/kern kern_timeout.c src/sys/sys callout.h src/share/man/man9 timeout.9 Message-ID: <6.0.1.1.1.20040407020834.03e0ae18@imap.sfu.ca> In-Reply-To: <20040406174517.F30594@root.org> References: <20040406230958.C01C616A545@hub.freebsd.org> <20040406162703.H30263@root.org> <6.0.1.1.1.20040407004244.03f85e80@imap.sfu.ca> <20040406174517.F30594@root.org>
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At 01:54 07/04/2004, Nate Lawson wrote:
>Nope, you've already included the check in your text so it can move as-is.
>Consider this example:
>
>+ if (wakeup_needed) {
>+ /*
>+ * There might be someone waiting
>+ * for the callout to complete.
>+ */
>
>wakeup_needed being non-zero means there is someone waiting for the
>callout to complete.
No. I wrote that comment very carefully; wakeup_needed being nonzero
means that there *might* be someone waiting for the callout to complete.
It's possible that the thread which wants to wait hasn't actually reached
cv_wait() yet -- thus the games with wakeup_ctr, wakeup_done_ctr, and
wakeup_cookie.
Colin Percival
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