From: Arjan van de Ven <arjanv@redhat.com>
To: Kurt Garloff <garloff@suse.de>,
Arjan van de Ven <arjanv@redhat.com>,
akpm@osdl.org, linux-scsi@vger.kernel.org
Subject: Re: fix corruption in qla1280
Date: Mon, 14 Jul 2003 21:01:48 +0000 [thread overview]
Message-ID: <20030714210148.B32473@devserv.devel.redhat.com> (raw)
In-Reply-To: <20030714204315.GL6108@nbkurt.garloff.de>; from garloff@suse.de on Mon, Jul 14, 2003 at 10:43:15PM +0200
On Mon, Jul 14, 2003 at 10:43:15PM +0200, Kurt Garloff wrote:
> Arjan,
>
> On Mon, Jul 14, 2003 at 09:24:37AM +0000, Arjan van de Ven wrote:
> > In C, doing >> 32 on a 32 bit wide variable is undefined behavior, and the
> > code that gets generated by gcc (using the cpu shr) effectively means that
> > it's a nop. The patch below to qla1280.c fixes such a case, doing
> > >>16 twice looks more expensive but gcc optimizes it out while keeping
> > correct behavior.
>
> If it's really a 32 bit variable,
> #define pci_dma_hi32(a) (0)
> would be correct. Shifting a 32bit value 32times to the right is just 0.
> What do I miss?
it's only a 32 bit variable on 32 bit platforms
(or rather, when dma_addr_t is 32 bit.. the ifdefs for that get evil)
prev parent reply other threads:[~2003-07-14 20:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-14 9:24 fix corruption in qla1280 Arjan van de Ven
2003-07-14 20:43 ` Kurt Garloff
2003-07-14 21:01 ` Arjan van de Ven [this message]
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