linux-kernel - [PATCH] Document SEQ

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Message-ID: <16841.1208968750@vena.lwn.net>
Date:	Wed, 23 Apr 2008 10:39:10 -0600
From:	Jonathan Corbet <corbet@....net>
To:	linux-kernel@...r.kernel.org
cc:	viro@...celfarce.linux.theplanet.co.uk
Subject: [PATCH] Document SEQ_SKIP

I noticed that SEQ_SKIP went into the mainline; here's a little doc fix
to match.  I'll feed this up through my docs tree unless somebody else
wants it.

jon

--
    Document SEQ_SKIP
    
    2.6.26 adds a SEQ_SKIP return value for the seq_file show() function;
    update the documentation to match.
    
    Signed-off-by: Jonathan Corbet <corbet@....net>

diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt
index 7fb8e6d..0ab92c2 100644
--- a/Documentation/filesystems/seq_file.txt
+++ b/Documentation/filesystems/seq_file.txt
@@ -122,8 +122,7 @@ stop() is the place to free it.
 	}
 
 Finally, the show() function should format the object currently pointed to
-by the iterator for output. It should return zero, or an error code if
-something goes wrong. The example module's show() function is:
+by the iterator for output.  The example module's show() function is:
 
 	static int ct_seq_show(struct seq_file *s, void *v)
 	{
@@ -132,6 +131,12 @@ something goes wrong. The example module's show() function is:
 	        return 0;
 	}
 
+If all is well, the show() function should return zero.  A negative error
+code in the usual manner indicates that something went wrong; it will be
+passed back to user space.  This function can also return SEQ_SKIP, which
+causes the current item to be skipped; if the show() function has already
+generated output before returning SEQ_SKIP, that output will be dropped.
+
 We will look at seq_printf() in a moment. But first, the definition of the
 seq_file iterator is finished by creating a seq_operations structure with
 the four functions we have just defined:
--
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