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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>,
	linux-mmc@vger.kernel.org, Chris Ball <chris@printf.net>,
	linux-arm-kernel@lists.infradead.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH] Fix uses of dma_max_pfn() when converting to a limiting address
Date: Thu, 13 Feb 2014 17:11:17 +0000	[thread overview]
Message-ID: <20140213171117.GA30257@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1392310690.2175.13.camel@dabdike.int.hansenpartnership.com>

On Thu, Feb 13, 2014 at 08:58:10AM -0800, James Bottomley wrote:
> This doesn't really look like the right fix.  You replaced dev->dma_mask
> with a calculation on dev_max_pfn().  Since dev->dma_mask is always u64
> and dev_max_pfn is supposed to be returning the pfn of the dma_mask, it
> should unconditionally be 64 bits as well.  Either that or it should
> return dma_addr_t.

My reasoning is that PFNs in the system are always of type "unsigned long"
and therefore a function returning a pfn should have that type.  If we
overflow a PFN fitting in an unsigned long, we have lots of places which
need fixing.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".

  reply	other threads:[~2014-02-13 17:11 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-11 17:28 [PATCH] Fix uses of dma_max_pfn() when converting to a limiting address Russell King
2014-02-13 16:34 ` Santosh Shilimkar
2014-02-13 16:58 ` James Bottomley
2014-02-13 17:11   ` Russell King - ARM Linux [this message]
2014-02-13 18:07     ` James Bottomley
2014-02-13 20:01       ` Russell King - ARM Linux
2014-02-17 12:43         ` Russell King - ARM Linux
2014-02-17 13:39 ` Ulf Hansson

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