diff options
| author | Vishal Verma <vishal.l.verma@intel.com> | 2023-01-25 21:34:18 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-03 13:40:07 +0300 |
| commit | 5f8401d7dba21e549306fe4a7a9ff8bf3bd8d56a (patch) | |
| tree | 77efad41c1ce2fc8644f3ed55bba803add16b117 /drivers/acpi | |
| parent | 5df89a6a1c1d6bcb4b0f5a641cb0b9f1e6ce48fc (diff) | |
| download | linux-5f8401d7dba21e549306fe4a7a9ff8bf3bd8d56a.tar.xz | |
ACPI: NFIT: fix a potential deadlock during NFIT teardown
[ Upstream commit fb6df4366f86dd252bfa3049edffa52d17e7b895 ]
Lockdep reports that acpi_nfit_shutdown() may deadlock against an
opportune acpi_nfit_scrub(). acpi_nfit_scrub () is run from inside a
'work' and therefore has already acquired workqueue-internal locks. It
also acquiires acpi_desc->init_mutex. acpi_nfit_shutdown() first
acquires init_mutex, and was subsequently attempting to cancel any
pending workqueue items. This reversed locking order causes a potential
deadlock:
======================================================
WARNING: possible circular locking dependency detected
6.2.0-rc3 #116 Tainted: G O N
------------------------------------------------------
libndctl/1958 is trying to acquire lock:
ffff888129b461c0 ((work_completion)(&(&acpi_desc->dwork)->work)){+.+.}-{0:0}, at: __flush_work+0x43/0x450
but task is already holding lock:
ffff888129b460e8 (&acpi_desc->init_mutex){+.+.}-{3:3}, at: acpi_nfit_shutdown+0x87/0xd0 [nfit]
which lock already depends on the new lock.
...
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&acpi_desc->init_mutex);
lock((work_completion)(&(&acpi_desc->dwork)->work));
lock(&acpi_desc->init_mutex);
lock((work_completion)(&(&acpi_desc->dwork)->work));
*** DEADLOCK ***
Since the workqueue manipulation is protected by its own internal locking,
the cancellation of pending work doesn't need to be done under
acpi_desc->init_mutex. Move cancel_delayed_work_sync() outside the
init_mutex to fix the deadlock. Any work that starts after
acpi_nfit_shutdown() drops the lock will see ARS_CANCEL, and the
cancel_delayed_work_sync() will safely flush it out.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/20230112-acpi_nfit_lockdep-v1-1-660be4dd10be@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/acpi')
| -rw-r--r-- | drivers/acpi/nfit/core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c index 58a756ca14d8..c2863eec0f24 100644 --- a/drivers/acpi/nfit/core.c +++ b/drivers/acpi/nfit/core.c @@ -3442,8 +3442,8 @@ void acpi_nfit_shutdown(void *data) mutex_lock(&acpi_desc->init_mutex); set_bit(ARS_CANCEL, &acpi_desc->scrub_flags); - cancel_delayed_work_sync(&acpi_desc->dwork); mutex_unlock(&acpi_desc->init_mutex); + cancel_delayed_work_sync(&acpi_desc->dwork); /* * Bounce the nvdimm bus lock to make sure any in-flight |