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![Dan Williams](/assets/img/avatar_default.png)
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: e8d5134833
("memremap: change devm_memremap_pages interface...")
Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com>
Reported-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
153 lines
3.9 KiB
C
153 lines
3.9 KiB
C
/*
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* Copyright(c) 2016 Intel Corporation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/percpu-refcount.h>
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#include <linux/memremap.h>
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#include <linux/module.h>
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#include <linux/pfn_t.h>
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#include "../nvdimm/pfn.h"
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#include "../nvdimm/nd.h"
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#include "device-dax.h"
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struct dax_pmem {
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struct device *dev;
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struct percpu_ref ref;
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struct dev_pagemap pgmap;
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struct completion cmp;
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};
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static struct dax_pmem *to_dax_pmem(struct percpu_ref *ref)
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{
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return container_of(ref, struct dax_pmem, ref);
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}
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static void dax_pmem_percpu_release(struct percpu_ref *ref)
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{
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struct dax_pmem *dax_pmem = to_dax_pmem(ref);
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dev_dbg(dax_pmem->dev, "trace\n");
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complete(&dax_pmem->cmp);
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}
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static void dax_pmem_percpu_exit(void *data)
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{
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struct percpu_ref *ref = data;
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struct dax_pmem *dax_pmem = to_dax_pmem(ref);
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dev_dbg(dax_pmem->dev, "trace\n");
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wait_for_completion(&dax_pmem->cmp);
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percpu_ref_exit(ref);
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}
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static void dax_pmem_percpu_kill(struct percpu_ref *ref)
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{
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struct dax_pmem *dax_pmem = to_dax_pmem(ref);
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dev_dbg(dax_pmem->dev, "trace\n");
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percpu_ref_kill(ref);
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}
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static int dax_pmem_probe(struct device *dev)
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{
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void *addr;
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struct resource res;
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int rc, id, region_id;
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struct nd_pfn_sb *pfn_sb;
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struct dev_dax *dev_dax;
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struct dax_pmem *dax_pmem;
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struct nd_namespace_io *nsio;
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struct dax_region *dax_region;
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struct nd_namespace_common *ndns;
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struct nd_dax *nd_dax = to_nd_dax(dev);
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struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
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ndns = nvdimm_namespace_common_probe(dev);
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if (IS_ERR(ndns))
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return PTR_ERR(ndns);
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nsio = to_nd_namespace_io(&ndns->dev);
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dax_pmem = devm_kzalloc(dev, sizeof(*dax_pmem), GFP_KERNEL);
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if (!dax_pmem)
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return -ENOMEM;
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/* parse the 'pfn' info block via ->rw_bytes */
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rc = devm_nsio_enable(dev, nsio);
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if (rc)
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return rc;
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rc = nvdimm_setup_pfn(nd_pfn, &dax_pmem->pgmap);
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if (rc)
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return rc;
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devm_nsio_disable(dev, nsio);
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pfn_sb = nd_pfn->pfn_sb;
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if (!devm_request_mem_region(dev, nsio->res.start,
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resource_size(&nsio->res),
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dev_name(&ndns->dev))) {
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dev_warn(dev, "could not reserve region %pR\n", &nsio->res);
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return -EBUSY;
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}
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dax_pmem->dev = dev;
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init_completion(&dax_pmem->cmp);
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rc = percpu_ref_init(&dax_pmem->ref, dax_pmem_percpu_release, 0,
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GFP_KERNEL);
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if (rc)
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return rc;
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rc = devm_add_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref);
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if (rc) {
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percpu_ref_exit(&dax_pmem->ref);
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return rc;
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}
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dax_pmem->pgmap.ref = &dax_pmem->ref;
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dax_pmem->pgmap.kill = dax_pmem_percpu_kill;
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addr = devm_memremap_pages(dev, &dax_pmem->pgmap);
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if (IS_ERR(addr))
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return PTR_ERR(addr);
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/* adjust the dax_region resource to the start of data */
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memcpy(&res, &dax_pmem->pgmap.res, sizeof(res));
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res.start += le64_to_cpu(pfn_sb->dataoff);
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rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", ®ion_id, &id);
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if (rc != 2)
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return -EINVAL;
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dax_region = alloc_dax_region(dev, region_id, &res,
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le32_to_cpu(pfn_sb->align), addr, PFN_DEV|PFN_MAP);
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if (!dax_region)
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return -ENOMEM;
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/* TODO: support for subdividing a dax region... */
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dev_dax = devm_create_dev_dax(dax_region, id, &res, 1);
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/* child dev_dax instances now own the lifetime of the dax_region */
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dax_region_put(dax_region);
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return PTR_ERR_OR_ZERO(dev_dax);
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}
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static struct nd_device_driver dax_pmem_driver = {
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.probe = dax_pmem_probe,
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.drv = {
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.name = "dax_pmem",
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},
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.type = ND_DRIVER_DAX_PMEM,
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};
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module_nd_driver(dax_pmem_driver);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Intel Corporation");
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MODULE_ALIAS_ND_DEVICE(ND_DEVICE_DAX_PMEM);
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