Re: [PATCH RFC PKS/PMEM 57/58] nvdimm/pmem: Stray access protection for pmem->virt_addr
From: John Hubbard <jhubbard@nvidia.com>
Date: 2020-10-10 03:16:50
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On 10/9/20 12:50 PM, ira.weiny@intel.com wrote:
quoted hunk ↗ jump to hunk
From: Ira Weiny <ira.weiny@intel.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@intel.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