On Thu, 2015-05-28 at 15:47 -0700, Dan Williams wrote: > On Thu, May 28, 2015 at 3:35 PM, Ross Zwisler > <ross.zwisler@xxxxxxxxxxxxxxx> wrote: > > Even though we use ioremap_nocache() to map our persistent memory > > in the > > pmem driver, the memory we are mapping behaves like normal memory > > and > > not I/O memory in that it can be accessed using regular memcpy() > > operations and doesn't need to go through memcpy_toio() and > > memcpy_fromio(). Force casting the pointers received from > > ioremap_nocache() and given to iounmap() gives us the correct > > behavior > > and makes sparse happy. > > > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > > Cc: linux-nvdimm@xxxxxxxxxxxx > > --- > > drivers/block/nd/pmem.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/block/nd/pmem.c b/drivers/block/nd/pmem.c > > index 5e8c9c629f22..a8712e41e7f5 100644 > > --- a/drivers/block/nd/pmem.c > > +++ b/drivers/block/nd/pmem.c > > @@ -163,7 +163,8 @@ static struct pmem_device *pmem_alloc(struct > > device *dev, struct resource *res, > > * of the CPU caches in case of a crash. > > */ > > err = -ENOMEM; > > - pmem->virt_addr = ioremap_nocache(pmem->phys_addr, pmem > > ->size); > > + pmem->virt_addr = (__force void *)ioremap_nocache(pmem > > ->phys_addr, > > + pmem->size); > > I think I'd rather see casting when ->virt_addr is used (the > __io_virt() helper can be used to make this a tad cleaner), or > provide > ioremap apis that don't attach __iomem to their return value. > Because > in this and other cases ioremap() is being on non "i/o" memory. The reason that I thought this was cleaner was that now when you look at the pmem->virt_addr definition it is just a clean void* with no annotations. This correctly describes the memory to the user (it's usable as regular memory, it's in the kernel address space, etc.). Having the pointer itself annotated with __iomem feels weird to me because a random well meaning user could incorrectly try to use it as I/O memory. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
