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a95c90f1e2
The last step before devm_memremap_pages() returns success is to allocate
a release action, devm_memremap_pages_release(), to tear the entire setup
down. However, the result from devm_add_action() is not checked.
Checking the error from devm_add_action() is not enough. The api
currently relies on the fact that the percpu_ref it is using is killed by
the time the devm_memremap_pages_release() is run. Rather than continue
this awkward situation, offload the responsibility of killing the
percpu_ref to devm_memremap_pages_release() directly. This allows
devm_memremap_pages() to do the right thing relative to init failures and
shutdown.
Without this change we could fail to register the teardown of
devm_memremap_pages(). The likelihood of hitting this failure is tiny as
small memory allocations almost always succeed. However, the impact of
the failure is large given any future reconfiguration, or disable/enable,
of an nvdimm namespace will fail forever as subsequent calls to
devm_memremap_pages() will fail to setup the pgmap_radix since there will
be stale entries for the physical address range.
An argument could be made to require that the ->kill() operation be set in
the @pgmap arg rather than passed in separately. However, it helps code
readability, tracking the lifetime of a given instance, to be able to grep
the kill routine directly at the devm_memremap_pages() call site.
Link: http://lkml.kernel.org/r/154275558526.76910.7535251937849268605.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Fixes:
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| .. | ||
| accounting | ||
| arch | ||
| bpf | ||
| build | ||
| cgroup | ||
| crypto | ||
| firewire | ||
| gpio | ||
| hv | ||
| iio | ||
| include | ||
| kvm/kvm_stat | ||
| laptop | ||
| leds | ||
| lib | ||
| memory-model | ||
| nfsd | ||
| objtool | ||
| pci | ||
| pcmcia | ||
| perf | ||
| power | ||
| scripts | ||
| spi | ||
| testing | ||
| thermal/tmon | ||
| time | ||
| usb | ||
| virtio | ||
| vm | ||
| wmi | ||
| Makefile | ||