Date: Thu, 4 May 2017 02:51:34 -0700 From: Christoph Hellwig <hch@...radead.org> To: Tycho Andersen <tycho@...ker.com> Cc: Tejun Heo <tj@...nel.org>, Juerg Haefliger <juerg.haefliger@....com>, linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com Subject: Re: [PATCH] ata-sff: always map page before data transfer > I don't understand all the factors at play here, so thoughts are definitely > welcome. I don't fully understand the old code either. One thing that is weird is the "use a bounce buffer comment" which doesn't make any sense. The other is the local_irq_save, which isn't really needed for kmap_atomic to start with, but maybe that's the reason why the original author didn't want to do it unconditionally? So based on that: > + /* FIXME: use a bounce buffer */ drop this comment.. > + local_irq_save(flags); .. remove the local_irq_save/local_irq_restore .. > + /* do the actual data transfer */ > + ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size, > + do_write); .. and a nice alittle cleanup move the do_write onto the previous line. > + /* FIXME: use bounce buffer */ > + local_irq_save(flags); > + buf = kmap_atomic(page); > > + /* do the actual data transfer */ > + consumed = ap->ops->sff_data_xfer(qc, buf + offset, > + count, rw); And same here. And we should be fine.
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