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Date: Fri, 9 Oct 2020 19:53:07 -0700 From: John Hubbard <jhubbard@...dia.com> To: <ira.weiny@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, "Thomas Gleixner" <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org> CC: <x86@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, Dan Williams <dan.j.williams@...el.com>, Fenghua Yu <fenghua.yu@...el.com>, <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <linux-nvdimm@...ts.01.org>, <linux-fsdevel@...r.kernel.org>, <linux-mm@...ck.org>, <linux-kselftest@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>, <kvm@...r.kernel.org>, <netdev@...r.kernel.org>, <bpf@...r.kernel.org>, <kexec@...ts.infradead.org>, <linux-bcache@...r.kernel.org>, <linux-mtd@...ts.infradead.org>, <devel@...verdev.osuosl.org>, <linux-efi@...r.kernel.org>, <linux-mmc@...r.kernel.org>, <linux-scsi@...r.kernel.org>, <target-devel@...r.kernel.org>, <linux-nfs@...r.kernel.org>, <ceph-devel@...r.kernel.org>, <linux-ext4@...r.kernel.org>, <linux-aio@...ck.org>, <io-uring@...r.kernel.org>, <linux-erofs@...ts.ozlabs.org>, <linux-um@...ts.infradead.org>, <linux-ntfs-dev@...ts.sourceforge.net>, <reiserfs-devel@...r.kernel.org>, <linux-f2fs-devel@...ts.sourceforge.net>, <linux-nilfs@...r.kernel.org>, <cluster-devel@...hat.com>, <ecryptfs@...r.kernel.org>, <linux-cifs@...r.kernel.org>, <linux-btrfs@...r.kernel.org>, <linux-afs@...ts.infradead.org>, <linux-rdma@...r.kernel.org>, <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>, <intel-gfx@...ts.freedesktop.org>, <drbd-dev@...ts.linbit.com>, <linux-block@...r.kernel.org>, <xen-devel@...ts.xenproject.org>, <linux-cachefs@...hat.com>, <samba-technical@...ts.samba.org>, <intel-wired-lan@...ts.osuosl.org> Subject: Re: [PATCH RFC PKS/PMEM 57/58] nvdimm/pmem: Stray access protection for pmem->virt_addr On 10/9/20 12:50 PM, ira.weiny@...el.com wrote: > From: Ira Weiny <ira.weiny@...el.com> > > The pmem driver uses a cached virtual address to access its memory > directly. Because the nvdimm driver is well aware of the special > protections it has mapped memory with, we call dev_access_[en|dis]able() > around the direct pmem->virt_addr (pmem_addr) usage instead of the > unnecessary overhead of trying to get a page to kmap. > > Signed-off-by: Ira Weiny <ira.weiny@...el.com> > --- > drivers/nvdimm/pmem.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c > index fab29b514372..e4dc1ae990fc 100644 > --- a/drivers/nvdimm/pmem.c > +++ b/drivers/nvdimm/pmem.c > @@ -148,7 +148,9 @@ static blk_status_t pmem_do_read(struct pmem_device *pmem, > if (unlikely(is_bad_pmem(&pmem->bb, sector, len))) > return BLK_STS_IOERR; > > + dev_access_enable(false); > rc = read_pmem(page, page_off, pmem_addr, len); > + dev_access_disable(false); Hi Ira! The APIs should be tweaked to use a symbol (GLOBAL, PER_THREAD), instead of true/false. Try reading the above and you'll see that it sounds like it's doing the opposite of what it is ("enable_this(false)" sounds like a clumsy API design to *disable*, right?). And there is no hint about the scope. And it *could* be so much more readable like this: dev_access_enable(DEV_ACCESS_THIS_THREAD); thanks, -- John Hubbard NVIDIA
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