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authorDan Williams <dan.j.williams@intel.com>2017-04-28 22:05:14 -0700
committerDan Williams <dan.j.williams@intel.com>2017-05-01 08:29:37 -0700
commit452bae0aede774f87bf56c28b6dd50b72c78986c (patch)
treef577780c5431059b334ae019ec8e3e8c6a652797 /drivers/nvdimm/claim.c
parent23f4984483623cf8621246004228f08fcabf51e4 (diff)
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+ #106 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: -> #1 (&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] -> #0 (&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: 8c2f7e8658df ("libnvdimm: infrastructure for btt devices") Reported-by: Yi Zhang <yizhan@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/nvdimm/claim.c')
-rw-r--r--drivers/nvdimm/claim.c23
1 files changed, 15 insertions, 8 deletions
diff --git a/drivers/nvdimm/claim.c b/drivers/nvdimm/claim.c
index 2c19bc7fc056..35b210dc1e56 100644
--- a/drivers/nvdimm/claim.c
+++ b/drivers/nvdimm/claim.c
@@ -21,8 +21,13 @@
void __nd_detach_ndns(struct device *dev, struct nd_namespace_common **_ndns)
{
struct nd_namespace_common *ndns = *_ndns;
+ struct nvdimm_bus *nvdimm_bus;
- lockdep_assert_held(&ndns->dev.mutex);
+ if (!ndns)
+ return;
+
+ nvdimm_bus = walk_to_nvdimm_bus(&ndns->dev);
+ lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
dev_WARN_ONCE(dev, ndns->claim != dev, "%s: invalid claim\n", __func__);
ndns->claim = NULL;
*_ndns = NULL;
@@ -37,18 +42,20 @@ void nd_detach_ndns(struct device *dev,
if (!ndns)
return;
get_device(&ndns->dev);
- device_lock(&ndns->dev);
+ nvdimm_bus_lock(&ndns->dev);
__nd_detach_ndns(dev, _ndns);
- device_unlock(&ndns->dev);
+ nvdimm_bus_unlock(&ndns->dev);
put_device(&ndns->dev);
}
bool __nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
struct nd_namespace_common **_ndns)
{
+ struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&attach->dev);
+
if (attach->claim)
return false;
- lockdep_assert_held(&attach->dev.mutex);
+ lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
dev_WARN_ONCE(dev, *_ndns, "%s: invalid claim\n", __func__);
attach->claim = dev;
*_ndns = attach;
@@ -61,9 +68,9 @@ bool nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
{
bool claimed;
- device_lock(&attach->dev);
+ nvdimm_bus_lock(&attach->dev);
claimed = __nd_attach_ndns(dev, attach, _ndns);
- device_unlock(&attach->dev);
+ nvdimm_bus_unlock(&attach->dev);
return claimed;
}
@@ -114,7 +121,7 @@ static void nd_detach_and_reset(struct device *dev,
struct nd_namespace_common **_ndns)
{
/* detach the namespace and destroy / reset the device */
- nd_detach_ndns(dev, _ndns);
+ __nd_detach_ndns(dev, _ndns);
if (is_idle(dev, *_ndns)) {
nd_device_unregister(dev, ND_ASYNC);
} else if (is_nd_btt(dev)) {
@@ -184,7 +191,7 @@ ssize_t nd_namespace_store(struct device *dev,
}
WARN_ON_ONCE(!is_nvdimm_bus_locked(dev));
- if (!nd_attach_ndns(dev, ndns, _ndns)) {
+ if (!__nd_attach_ndns(dev, ndns, _ndns)) {
dev_dbg(dev, "%s already claimed\n",
dev_name(&ndns->dev));
len = -EBUSY;