On Fri, Aug 27, 2021 at 7:59 AM Joao Martins <joao.m.martins@xxxxxxxxxx> wrote:
>
> Right now, only static dax regions have a valid @pgmap pointer in its
> struct dev_dax. Dynamic dax case however, do not.
>
> In preparation for device-dax compound devmap support, make sure that
> dev_dax pgmap field is set after it has been allocated and initialized.
>
> dynamic dax device have the @pgmap is allocated at probe() and it's
> managed by devm (contrast to static dax region which a pgmap is provided
> and dax core kfrees it). So in addition to ensure a valid @pgmap, clear
> the pgmap when the dynamic dax device is released to avoid the same
> pgmap ranges to be re-requested across multiple region device reconfigs.
>
> Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
> ---
> drivers/dax/bus.c | 8 ++++++++
> drivers/dax/device.c | 2 ++
> 2 files changed, 10 insertions(+)
>
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 6cc4da4c713d..49dbff9ba609 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -363,6 +363,14 @@ void kill_dev_dax(struct dev_dax *dev_dax)
>
> kill_dax(dax_dev);
> unmap_mapping_range(inode->i_mapping, 0, 0, 1);
> +
> + /*
> + * Dynamic dax region have the pgmap allocated via dev_kzalloc()
> + * and thus freed by devm. Clear the pgmap to not have stale pgmap
> + * ranges on probe() from previous reconfigurations of region devices.
> + */
> + if (!is_static(dev_dax->region))
> + dev_dax->pgmap = NULL;
> }
> EXPORT_SYMBOL_GPL(kill_dev_dax);
>
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index 0b82159b3564..6e348b5f9d45 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -426,6 +426,8 @@ int dev_dax_probe(struct dev_dax *dev_dax)
> }
>
> pgmap->type = MEMORY_DEVICE_GENERIC;
> + dev_dax->pgmap = pgmap;
So I think I'd rather see a bigger patch that replaces some of the
implicit dev_dax->pgmap == NULL checks with explicit is_static()
checks. Something like the following only compile and boot tested...
Note the struct_size() change probably wants to be its own cleanup,
and the EXPORT_SYMBOL_NS_GPL(..., DAX) probably wants to be its own
patch converting over the entirety of drivers/dax/. Thoughts?
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 6cc4da4c713d..67ab7e05b340 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -134,6 +134,12 @@ static bool is_static(struct dax_region *dax_region)
return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0;
}
+bool static_dev_dax(struct dev_dax *dev_dax)
+{
+ return is_static(dev_dax->region);
+}
+EXPORT_SYMBOL_NS_GPL(static_dev_dax, DAX);
+
static u64 dev_dax_size(struct dev_dax *dev_dax)
{
u64 size = 0;
@@ -363,6 +369,8 @@ void kill_dev_dax(struct dev_dax *dev_dax)
kill_dax(dax_dev);
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
+ if (static_dev_dax(dev_dax))
+ dev_dax->pgmap = NULL;
}
EXPORT_SYMBOL_GPL(kill_dev_dax);
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index 1e946ad7780a..4acdfee7dd59 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -48,6 +48,7 @@ int __dax_driver_register(struct dax_device_driver *dax_drv,
__dax_driver_register(driver, THIS_MODULE, KBUILD_MODNAME)
void dax_driver_unregister(struct dax_device_driver *dax_drv);
void kill_dev_dax(struct dev_dax *dev_dax);
+bool static_dev_dax(struct dev_dax *dev_dax);
#if IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)
int dev_dax_probe(struct dev_dax *dev_dax);
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index dd8222a42808..87507aff2b10 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -398,31 +398,43 @@ int dev_dax_probe(struct dev_dax *dev_dax)
void *addr;
int rc, i;
- pgmap = dev_dax->pgmap;
- if (dev_WARN_ONCE(dev, pgmap && dev_dax->nr_range > 1,
- "static pgmap / multi-range device conflict\n"))
+ if (static_dev_dax(dev_dax) && dev_dax->nr_range > 1) {
+ dev_warn(dev, "static pgmap / multi-range device conflict\n");
return -EINVAL;
+ }
- if (!pgmap) {
- pgmap = devm_kzalloc(dev, sizeof(*pgmap) + sizeof(struct range)
- * (dev_dax->nr_range - 1), GFP_KERNEL);
+ if (static_dev_dax(dev_dax)) {
+ pgmap = dev_dax->pgmap;
+ } else {
+ if (dev_dax->pgmap) {
+ dev_warn(dev,
+ "dynamic-dax with pre-populated page map!?\n");
+ return -EINVAL;
+ }
+ pgmap = devm_kzalloc(
+ dev, struct_size(pgmap, ranges, dev_dax->nr_range - 1),
+ GFP_KERNEL);
if (!pgmap)
return -ENOMEM;
pgmap->nr_range = dev_dax->nr_range;
+ dev_dax->pgmap = pgmap;
+ for (i = 0; i < dev_dax->nr_range; i++) {
+ struct range *range = &dev_dax->ranges[i].range;
+
+ pgmap->ranges[i] = *range;
+ }
}
for (i = 0; i < dev_dax->nr_range; i++) {
struct range *range = &dev_dax->ranges[i].range;
- if (!devm_request_mem_region(dev, range->start,
- range_len(range), dev_name(dev))) {
- dev_warn(dev, "mapping%d: %#llx-%#llx could
not reserve range\n",
- i, range->start, range->end);
- return -EBUSY;
- }
- /* don't update the range for static pgmap */
- if (!dev_dax->pgmap)
- pgmap->ranges[i] = *range;
+ if (devm_request_mem_region(dev, range->start, range_len(range),
+ dev_name(dev)))
+ continue;
+ dev_warn(dev,
+ "mapping%d: %#llx-%#llx could not reserve range\n", i,
+ range->start, range->end);
+ return -EBUSY;
}
pgmap->type = MEMORY_DEVICE_GENERIC;
@@ -473,3 +485,4 @@ MODULE_LICENSE("GPL v2");
module_init(dax_init);
module_exit(dax_exit);
MODULE_ALIAS_DAX_DEVICE(0);
+MODULE_IMPORT_NS(DAX);
> +
> addr = devm_memremap_pages(dev, pgmap);
> if (IS_ERR(addr))
> return PTR_ERR(addr);
> --
> 2.17.1
>
