From 452bae0aede774f87bf56c28b6dd50b72c78986c Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 28 Apr 2017 22:05:14 -0700 Subject: 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: [] nd_attach_ndns+0x178/0x1b0 [libnvdimm] but task is already holding lock: (&nvdimm_bus->reconfig_mutex){+.+.+.}, at: [] 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: Fixes: 8c2f7e8658df ("libnvdimm: infrastructure for btt devices") Reported-by: Yi Zhang Signed-off-by: Dan Williams --- drivers/nvdimm/claim.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) (limited to 'drivers/nvdimm/claim.c') 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; -- cgit v1.2.3-59-g8ed1b