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Subject: do_div considered harmful
Date: Mon, 4 Aug 2003 04:03:53 +0200 (MEST)	[thread overview]
Message-ID: <> (raw)

Writing this ide capacity patch an hour ago or so
I split off a helper sectors_to_MB() since Erik's recent
patch uses this also.
Now that I compare, he wrote
	nativeMb = do_div(nativeMb, 1000000);
to divide nativeMb by 1000000.
Similarly, I find in fs/cifs/inode.c
	inode->i_blocks = do_div(findData.NumOfBytes, inode->i_blksize);

So, it seems natural to expect that do_div() gives the quotient.
But it gives the remainder.
(Strange, Erik showed correct output.)

Since the semantics of this object are very unlike that of a C function,
I wonder whether we should write DO_DIV instead, or DO_DIV_AND_REM
to show that a remainder is returned.


             reply	other threads:[~2003-08-04  2:03 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-08-04  2:03 Andries.Brouwer [this message]
2003-08-04  2:29 ` do_div considered harmful Andrew Morton
2003-08-05  2:58   ` i_blksize Andries Brouwer
2003-08-05  6:10     ` i_blksize Andrew Morton
2003-08-04  5:54 ` do_div considered harmful Linus Torvalds
2003-08-04  5:31 Steve French
2003-08-04  9:46 Andries.Brouwer

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