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linux-next/drivers/nvdimm/dax_devs.c
Dan Williams 452bae0aed libnvdimm: fix nvdimm_bus_lock() vs device_lock() ordering
A debug patch to turn the standard device_lock() into something that
lockdep can analyze yielded the following:

 ======================================================
 [ INFO: possible circular locking dependency detected ]
 4.11.0-rc4+  Tainted: G           O
 -------------------------------------------------------
 lt-libndctl/1898 is trying to acquire lock:
  (&dev->nvdimm_mutex/3){+.+.+.}, at: [<ffffffffc023c948>] nd_attach_ndns+0x178/0x1b0 [libnvdimm]

 but task is already holding lock:
  (&nvdimm_bus->reconfig_mutex){+.+.+.}, at: [<ffffffffc022e0b1>] nvdimm_bus_lock+0x21/0x30 [libnvdimm]

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 ->  (&nvdimm_bus->reconfig_mutex){+.+.+.}:
        lock_acquire+0xf6/0x1f0
        __mutex_lock+0x88/0x980
        mutex_lock_nested+0x1b/0x20
        nvdimm_bus_lock+0x21/0x30 [libnvdimm]
        nvdimm_namespace_capacity+0x1b/0x40 [libnvdimm]
        nvdimm_namespace_common_probe+0x230/0x510 [libnvdimm]
        nd_pmem_probe+0x14/0x180 [nd_pmem]
        nvdimm_bus_probe+0xa9/0x260 [libnvdimm]

 ->  (&dev->nvdimm_mutex/3){+.+.+.}:
        __lock_acquire+0x1107/0x1280
        lock_acquire+0xf6/0x1f0
        __mutex_lock+0x88/0x980
        mutex_lock_nested+0x1b/0x20
        nd_attach_ndns+0x178/0x1b0 [libnvdimm]
        nd_namespace_store+0x308/0x3c0 [libnvdimm]
        namespace_store+0x87/0x220 [libnvdimm]

In this case '&dev->nvdimm_mutex/3' mirrors '&dev->mutex'.

Fix this by replacing the use of device_lock() with nvdimm_bus_lock() to protect
nd_{attach,detach}_ndns() operations.

Cc: <stable@vger.kernel.org>
Fixes: 8c2f7e8658 ("libnvdimm: infrastructure for btt devices")
Reported-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-05-01 08:29:37 -07:00

135 lines
3.3 KiB
C

/*
* Copyright(c) 2013-2016 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/device.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include "nd-core.h"
#include "pfn.h"
#include "nd.h"
static void nd_dax_release(struct device *dev)
{
struct nd_region *nd_region = to_nd_region(dev->parent);
struct nd_dax *nd_dax = to_nd_dax(dev);
struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
dev_dbg(dev, "%s\n", __func__);
nd_detach_ndns(dev, &nd_pfn->ndns);
ida_simple_remove(&nd_region->dax_ida, nd_pfn->id);
kfree(nd_pfn->uuid);
kfree(nd_dax);
}
static struct device_type nd_dax_device_type = {
.name = "nd_dax",
.release = nd_dax_release,
};
bool is_nd_dax(struct device *dev)
{
return dev ? dev->type == &nd_dax_device_type : false;
}
EXPORT_SYMBOL(is_nd_dax);
struct nd_dax *to_nd_dax(struct device *dev)
{
struct nd_dax *nd_dax = container_of(dev, struct nd_dax, nd_pfn.dev);
WARN_ON(!is_nd_dax(dev));
return nd_dax;
}
EXPORT_SYMBOL(to_nd_dax);
static const struct attribute_group *nd_dax_attribute_groups[] = {
&nd_pfn_attribute_group,
&nd_device_attribute_group,
&nd_numa_attribute_group,
NULL,
};
static struct nd_dax *nd_dax_alloc(struct nd_region *nd_region)
{
struct nd_pfn *nd_pfn;
struct nd_dax *nd_dax;
struct device *dev;
nd_dax = kzalloc(sizeof(*nd_dax), GFP_KERNEL);
if (!nd_dax)
return NULL;
nd_pfn = &nd_dax->nd_pfn;
nd_pfn->id = ida_simple_get(&nd_region->dax_ida, 0, 0, GFP_KERNEL);
if (nd_pfn->id < 0) {
kfree(nd_dax);
return NULL;
}
dev = &nd_pfn->dev;
dev_set_name(dev, "dax%d.%d", nd_region->id, nd_pfn->id);
dev->groups = nd_dax_attribute_groups;
dev->type = &nd_dax_device_type;
dev->parent = &nd_region->dev;
return nd_dax;
}
struct device *nd_dax_create(struct nd_region *nd_region)
{
struct device *dev = NULL;
struct nd_dax *nd_dax;
if (!is_nd_pmem(&nd_region->dev))
return NULL;
nd_dax = nd_dax_alloc(nd_region);
if (nd_dax)
dev = nd_pfn_devinit(&nd_dax->nd_pfn, NULL);
__nd_device_register(dev);
return dev;
}
int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns)
{
int rc;
struct nd_dax *nd_dax;
struct device *dax_dev;
struct nd_pfn *nd_pfn;
struct nd_pfn_sb *pfn_sb;
struct nd_region *nd_region = to_nd_region(ndns->dev.parent);
if (ndns->force_raw)
return -ENODEV;
nvdimm_bus_lock(&ndns->dev);
nd_dax = nd_dax_alloc(nd_region);
nd_pfn = &nd_dax->nd_pfn;
dax_dev = nd_pfn_devinit(nd_pfn, ndns);
nvdimm_bus_unlock(&ndns->dev);
if (!dax_dev)
return -ENOMEM;
pfn_sb = devm_kzalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
nd_pfn->pfn_sb = pfn_sb;
rc = nd_pfn_validate(nd_pfn, DAX_SIG);
dev_dbg(dev, "%s: dax: %s\n", __func__,
rc == 0 ? dev_name(dax_dev) : "<none>");
if (rc < 0) {
nd_detach_ndns(dax_dev, &nd_pfn->ndns);
put_device(dax_dev);
} else
__nd_device_register(dax_dev);
return rc;
}
EXPORT_SYMBOL(nd_dax_probe);