On Tue, Aug 22, 2017 at 10:37:29AM +0300, Luca Coelho wrote:
> From: Luca Coelho <luciano.coelho@xxxxxxxxx>
>
> Work queues cannot be allocated when a mutex is held because the mutex
> may be in use and that would make it sleep. Doing so generates the
> following splat with 4.13+:
>
> [ 19.513298] ======================================================
> [ 19.513429] WARNING: possible circular locking dependency detected
> [ 19.513557] 4.13.0-rc5+ #6 Not tainted
> [ 19.513638] ------------------------------------------------------
> [ 19.513767] cpuhp/0/12 is trying to acquire lock:
> [ 19.513867] (&tz->lock){+.+.+.}, at: [<ffffffff924afebb>] thermal_zone_get_temp+0x5b/0xb0
> [ 19.514047]
> [ 19.514047] but task is already holding lock:
> [ 19.514166] (cpuhp_state){+.+.+.}, at: [<ffffffff91cc4baa>] cpuhp_thread_fun+0x3a/0x210
> [ 19.514338]
> [ 19.514338] which lock already depends on the new lock.
>
> This lock dependency already existed with previous kernel versions,
> but it was not detected until commit 49dfe2a67797 ("cpuhotplug: Link
> lock stacks for hotplug callbacks") was introduced.
>
> Reported-by: David Weinehall <david.weinehall@xxxxxxxxx>
> Reported-by: Jiri Kosina <jikos@xxxxxxxxxx>
> Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx>
With this patch I no longer get the lockdep warning,
and the driver seems to work just as well as before.
Thanks!
Tested-by: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx>
> ---
> In v2:
> - updated the commit message to a new version, with a grammar fix
> and the actual commit that exposed the problem;
>
> drivers/net/wireless/intel/iwlwifi/pcie/internal.h | 2 ++
> drivers/net/wireless/intel/iwlwifi/pcie/rx.c | 10 +---------
> drivers/net/wireless/intel/iwlwifi/pcie/trans.c | 9 +++++++++
> 3 files changed, 12 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/internal.h b/drivers/net/wireless/intel/iwlwifi/pcie/internal.h
> index fa315d84e98e..a1ea9ef97ed9 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/internal.h
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/internal.h
> @@ -787,6 +787,8 @@ int iwl_pci_fw_enter_d0i3(struct iwl_trans *trans);
>
> void iwl_pcie_enable_rx_wake(struct iwl_trans *trans, bool enable);
>
> +void iwl_pcie_rx_allocator_work(struct work_struct *data);
> +
> /* common functions that are used by gen2 transport */
> void iwl_pcie_apm_config(struct iwl_trans *trans);
> int iwl_pcie_prepare_card_hw(struct iwl_trans *trans);
> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
> index 351c4423125a..942736d3fa75 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
> @@ -597,7 +597,7 @@ static void iwl_pcie_rx_allocator_get(struct iwl_trans *trans,
> rxq->free_count += RX_CLAIM_REQ_ALLOC;
> }
>
> -static void iwl_pcie_rx_allocator_work(struct work_struct *data)
> +void iwl_pcie_rx_allocator_work(struct work_struct *data)
> {
> struct iwl_rb_allocator *rba_p =
> container_of(data, struct iwl_rb_allocator, rx_alloc);
> @@ -900,10 +900,6 @@ static int _iwl_pcie_rx_init(struct iwl_trans *trans)
> return err;
> }
> def_rxq = trans_pcie->rxq;
> - if (!rba->alloc_wq)
> - rba->alloc_wq = alloc_workqueue("rb_allocator",
> - WQ_HIGHPRI | WQ_UNBOUND, 1);
> - INIT_WORK(&rba->rx_alloc, iwl_pcie_rx_allocator_work);
>
> spin_lock(&rba->lock);
> atomic_set(&rba->req_pending, 0);
> @@ -1017,10 +1013,6 @@ void iwl_pcie_rx_free(struct iwl_trans *trans)
> }
>
> cancel_work_sync(&rba->rx_alloc);
> - if (rba->alloc_wq) {
> - destroy_workqueue(rba->alloc_wq);
> - rba->alloc_wq = NULL;
> - }
>
> iwl_pcie_free_rbs_pool(trans);
>
> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> index f95eec52508e..3927bbf04f72 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> @@ -1786,6 +1786,11 @@ void iwl_trans_pcie_free(struct iwl_trans *trans)
> iwl_pcie_tx_free(trans);
> iwl_pcie_rx_free(trans);
>
> + if (trans_pcie->rba.alloc_wq) {
> + destroy_workqueue(trans_pcie->rba.alloc_wq);
> + trans_pcie->rba.alloc_wq = NULL;
> + }
> +
> if (trans_pcie->msix_enabled) {
> for (i = 0; i < trans_pcie->alloc_vecs; i++) {
> irq_set_affinity_hint(
> @@ -3169,6 +3174,10 @@ struct iwl_trans *iwl_trans_pcie_alloc(struct pci_dev *pdev,
> trans_pcie->inta_mask = CSR_INI_SET_MASK;
> }
>
> + trans_pcie->rba.alloc_wq = alloc_workqueue("rb_allocator",
> + WQ_HIGHPRI | WQ_UNBOUND, 1);
> + INIT_WORK(&trans_pcie->rba.rx_alloc, iwl_pcie_rx_allocator_work);
> +
> #ifdef CONFIG_IWLWIFI_PCIE_RTPM
> trans->runtime_pm_mode = IWL_PLAT_PM_MODE_D0I3;
> #else
> --
> 2.14.1
>
