linux-kernel - __get_free_pages: can GFP_DMA omit GFP_KERNEL and GFP

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Message-ID: <Pine.LNX.4.64.0706030435130.14627@localhost.localdomain>
Date:	Sun, 3 Jun 2007 04:41:44 -0400 (EDT)
From:	"Robert P. J. Day" <rpjday@...dspring.com>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: __get_free_pages:  can GFP_DMA omit GFP_KERNEL and GFP_ATOMIC?

a two-parter:

  first, can a call to __get_free_pages to allocate DMA-able memory
omit specifying either of GFP_KERNEL or GFP_ATOMIC?  love's book on
kernel development strongly suggests you need to specify one or the
other, but there are a few instances in the tree like this:

drivers/s390/net/claw.c:                        (void *)__get_free_pages(__GFP_DMA,
drivers/s390/net/claw.c:                   p_buff=(void *)__get_free_pages(__GFP_DMA,

where you can see that the only type flag is __GFP_DMA.  is that
meaningful?

  and, second, i only noticed this as i was going to submit a short
patch to replace __get_free_pages calls for DMA-able memory with the
existing equivalent macro __get_dma_pages.  is that still considered a
worthwhile cleanup?  there's not that many examples of it, and it
would just make things consistent.

rday

-- 
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

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