From: Roland Dreier <roland@topspin.com>
To: root@chaos.analogic.com
Cc: Linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: poll() in 2.6 and beyond
Date: 02 Mar 2004 13:00:40 -0800 [thread overview]
Message-ID: <52vflnq807.fsf@topspin.com> (raw)
In-Reply-To: <Pine.LNX.4.53.0403021510270.1856@chaos>
Richard> I'm talking about the driver! When a open fd called
Richard> poll() or select(), in user-mode code, the driver's
Richard> poll() was called, and the driver's poll() would call
Richard> poll_wait(). Poll_wait() used to NOT return until the
Richard> driver executed wake_up_interruptible() on that
Richard> wait-queue. When poll_wait() returned, the driver would
Richard> return to the caller with the new poll- status.
I don't think so. Even in kernel 2.4, poll_wait() just calls
__pollwait(). I don't see anything in __pollwait() that sleeps.
Think about it. How would the kernel handle userspace calling poll()
with more than one file descriptor if each individual driver slept?
I'll repeat my earlier suggestion. Read the description of "poll and
select" in LDD:
<http://www.xml.com/ldd/chapter/book/ch05.html#t3>
If you refuse to understand the documented interface, I don't think
anyone can help you.
- Roland
next prev parent reply other threads:[~2004-03-02 21:00 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-02 18:21 poll() in 2.6 and beyond Richard B. Johnson
2004-03-02 20:04 ` Roland Dreier
2004-03-02 20:24 ` Richard B. Johnson
2004-03-02 21:00 ` Roland Dreier [this message]
2004-03-02 21:26 ` Richard B. Johnson
2004-03-02 21:39 ` Roland Dreier
2004-03-02 21:59 ` Richard B. Johnson
2004-03-02 22:41 ` Dave Dillow
2004-03-02 22:56 ` Roland Dreier
2004-03-02 23:16 ` Richard B. Johnson
2004-03-02 23:21 ` Roland Dreier
[not found] <1vmPm-4lU-11@gated-at.bofh.it>
[not found] ` <1vonq-6dr-37@gated-at.bofh.it>
[not found] ` <1voGY-6vC-41@gated-at.bofh.it>
[not found] ` <1vpjt-7dl-17@gated-at.bofh.it>
[not found] ` <1vpCV-7wY-41@gated-at.bofh.it>
[not found] ` <1vpWa-7Py-19@gated-at.bofh.it>
2004-03-02 22:53 ` Bill Davidsen
2004-03-02 22:57 ` Roland Dreier
2004-03-02 23:32 ` Richard B. Johnson
2004-03-03 0:07 ` John Muir
2004-03-03 1:18 ` Richard B. Johnson
2004-03-03 4:04 ` Roland Dreier
2004-03-03 12:38 ` Richard B. Johnson
2004-03-03 14:29 ` Davide Libenzi
2004-03-03 3:57 ` David Dillow
2004-03-03 18:23 ` Richard B. Johnson
2004-03-03 19:29 ` Dave Dillow
2004-03-03 20:10 ` Richard B. Johnson
2004-03-03 22:25 ` Linus Torvalds
2004-03-03 22:42 ` Richard B. Johnson
2004-03-03 23:14 ` Linus Torvalds
2004-03-03 22:52 ` Linus Torvalds
2004-03-03 23:07 ` Richard B. Johnson
-- strict thread matches above, loose matches on Subject: below --
2004-03-03 3:06 linux
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