From: corbet@lwn.net (Jonathan Corbet)
To: Michael Zhu <mylinuxk@yahoo.ca>
Cc: linux-kernel@vger.kernel.org
Subject: Re: The CURRENT macro
Date: Thu, 03 Jan 2002 14:48:39 -0700 [thread overview]
Message-ID: <20020103214839.9953.qmail@eklektix.com> (raw)
In-Reply-To: Your message of "Thu, 03 Jan 2002 16:34:55 EST." <20020103213455.34699.qmail@web14911.mail.yahoo.com>
> In Alessandro Rubini's book Linux Device Driver(Second
> Edition), Chatper 12
Alessandro and...um...some other guy...:)
> he said that "By accessing the
> fields in the request structure, usually by way of
> CURRENT" and "CURRENT is just a pointer into
> blk_dev[MAJOR_NR].request_queue". I know CURRENT is
> just a macro. Where can I find the definition of this
> macro?
A little grepping in the source would give you the answer there. It's in
.../include/linux/blk.h.
> I just don't know how to get the struct request from
> the request_queue(a request_queue_t struct). CURRENT
> points to which field in the
> blk_dev[MAJOR_NR].request_queue? Thank you very much.
CURRENT is one way. There's also functions like blkdev_entry_next_request
(also described in that chapter) that will pull a request off the queue for
you, if that's what you need.
Note that all this stuff has changed quite a bit in 2.5.
jon
Jonathan Corbet
Executive editor, LWN.net
corbet@lwn.net
next prev parent reply other threads:[~2002-01-03 21:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-03 21:34 The CURRENT macro Michael Zhu
2002-01-03 21:48 ` Jonathan Corbet [this message]
2002-01-03 21:55 ` Arnaldo Carvalho de Melo
2002-01-04 8:03 ` Terje Eggestad
2002-01-03 22:01 ` Richard B. Johnson
2002-01-03 22:14 ` Peter Makholm
2002-01-03 22:55 ` Tom Gall
2002-01-03 22:57 ` Tom Gall
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