[PATCH 5.14 181/432] iavf: fix locking of critical sections

Greg Kroah-Hartman
2021-09-16T17:29:32Z

From: Stefan Assmann <sassmann@kpanic.de>

[ Upstream commit 226d528512cfac890a1619aea4301f3dd314fe60 ]

To avoid races between iavf_init_task(), iavf_reset_task(),
iavf_watchdog_task(), iavf_adminq_task() as well as the shutdown and
remove functions more locking is required.
The current protection by __IAVF_IN_CRITICAL_TASK is needed in
additional places.

- The reset task performs state transitions, therefore needs locking.
- The adminq task acts on replies from the PF in
iavf_virtchnl_completion() which may alter the states.
- The init task is not only run during probe but also if a VF gets stuck
to reinitialize it.
- The shutdown function performs a state transition.
- The remove function performs a state transition and also free's
resources.

iavf_lock_timeout() is introduced to avoid waiting infinitely
and cause a deadlock. Rather unlock and print a warning.

Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/iavf/iavf_main.c | 57 ++++++++++++++++++---
1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index 0d0f16617dde..e5e6a5b11e6d 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_main.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
@@ -131,6 +131,30 @@ enum iavf_status iavf_free_virt_mem_d(struct iavf_hw *hw,
return 0;
}

+/**
+ * iavf_lock_timeout - try to set bit but give up after timeout
+ * @adapter: board private structure
+ * @bit: bit to set
+ * @msecs: timeout in msecs
+ *
+ * Returns 0 on success, negative on failure
+ **/
+static int iavf_lock_timeout(struct iavf_adapter *adapter,
+ enum iavf_critical_section_t bit,
+ unsigned int msecs)
+{
+ unsigned int wait, delay = 10;
+
+ for (wait = 0; wait < msecs; wait += delay) {
+ if (!test_and_set_bit(bit, &adapter->crit_section))
+ return 0;
+
+ msleep(delay);
+ }
+
+ return -1;
+}
+
/**
* iavf_schedule_reset - Set the flags and schedule a reset event
* @adapter: board private structure
@@ -2097,6 +2121,10 @@ static void iavf_reset_task(struct work_struct *work)
if (test_bit(__IAVF_IN_REMOVE_TASK, &adapter->crit_section))
return;

+ if (iavf_lock_timeout(adapter, __IAVF_IN_CRITICAL_TASK, 200)) {
+ schedule_work(&adapter->reset_task);
+ return;
+ }
while (test_and_set_bit(__IAVF_IN_CLIENT_TASK,
&adapter->crit_section))
usleep_range(500, 1000);
@@ -2311,6 +2339,8 @@ static void iavf_adminq_task(struct work_struct *work)
if (!event.msg_buf)
goto out;

+ if (iavf_lock_timeout(adapter, __IAVF_IN_CRITICAL_TASK, 200))
+ goto freedom;
do {
ret = iavf_clean_arq_element(hw, &event, &pending);
v_op = (enum virtchnl_ops)le32_to_cpu(event.desc.cookie_high);
@@ -2324,6 +2354,7 @@ static void iavf_adminq_task(struct work_struct *work)
if (pending != 0)
memset(event.msg_buf, 0, IAVF_MAX_AQ_BUF_SIZE);
} while (pending);
+ clear_bit(__IAVF_IN_CRITICAL_TASK, &adapter->crit_section);

if ((adapter->flags &
(IAVF_FLAG_RESET_PENDING | IAVF_FLAG_RESET_NEEDED)) ||
@@ -3628,6 +3659,10 @@ static void iavf_init_task(struct work_struct *work)
init_task.work);
struct iavf_hw *hw = &adapter->hw;

+ if (iavf_lock_timeout(adapter, __IAVF_IN_CRITICAL_TASK, 5000)) {
+ dev_warn(&adapter->pdev->dev, "failed to set __IAVF_IN_CRITICAL_TASK in %s\n", __FUNCTION__);
+ return;
+ }
switch (adapter->state) {
case __IAVF_STARTUP:
if (iavf_startup(adapter) < 0)
@@ -3640,14 +3675,14 @@ static void iavf_init_task(struct work_struct *work)
case __IAVF_INIT_GET_RESOURCES:
if (iavf_init_get_resources(adapter) < 0)
goto init_failed;
- return;
+ goto out;
default:
goto init_failed;
}

queue_delayed_work(iavf_wq, &adapter->init_task,
msecs_to_jiffies(30));
- return;
+ goto out;
init_failed:
if (++adapter->aq_wait_count > IAVF_AQ_MAX_ERR) {
dev_err(&adapter->pdev->dev,
@@ -3656,9 +3691,11 @@ static void iavf_init_task(struct work_struct *work)
iavf_shutdown_adminq(hw);
adapter->state = __IAVF_STARTUP;
queue_delayed_work(iavf_wq, &adapter->init_task, HZ * 5);
- return;
+ goto out;
}
queue_delayed_work(iavf_wq, &adapter->init_task, HZ);
+out:
+ clear_bit(__IAVF_IN_CRITICAL_TASK, &adapter->crit_section);
}

/**
@@ -3675,9 +3712,12 @@ static void iavf_shutdown(struct pci_dev *pdev)
if (netif_running(netdev))
iavf_close(netdev);

+ if (iavf_lock_timeout(adapter, __IAVF_IN_CRITICAL_TASK, 5000))
+ dev_warn(&adapter->pdev->dev, "failed to set __IAVF_IN_CRITICAL_TASK in %s\n", __FUNCTION__);
/* Prevent the watchdog from running. */
adapter->state = __IAVF_REMOVE;
adapter->aq_required = 0;
+ clear_bit(__IAVF_IN_CRITICAL_TASK, &adapter->crit_section);

#ifdef CONFIG_PM
pci_save_state(pdev);
@@ -3911,10 +3951,6 @@ static void iavf_remove(struct pci_dev *pdev)
err);
}

- /* Shut down all the garbage mashers on the detention level */
- adapter->state = __IAVF_REMOVE;
- adapter->aq_required = 0;
- adapter->flags &= ~IAVF_FLAG_REINIT_ITR_NEEDED;
iavf_request_reset(adapter);
msleep(50);
/* If the FW isn't responding, kick it once, but only once. */
@@ -3922,6 +3958,13 @@ static void iavf_remove(struct pci_dev *pdev)
iavf_request_reset(adapter);
msleep(50);
}
+ if (iavf_lock_timeout(adapter, __IAVF_IN_CRITICAL_TASK, 5000))
+ dev_warn(&adapter->pdev->dev, "failed to set __IAVF_IN_CRITICAL_TASK in %s\n", __FUNCTION__);
+
+ /* Shut down all the garbage mashers on the detention level */
+ adapter->state = __IAVF_REMOVE;
+ adapter->aq_required = 0;
+ adapter->flags &= ~IAVF_FLAG_REINIT_ITR_NEEDED;
iavf_free_all_tx_resources(adapter);
iavf_free_all_rx_resources(adapter);
iavf_misc_irq_disable(adapter);
--
2.30.2