On Tue, 2021-01-12 at 10:14 -0800, Sukadev Bhattiprolu wrote:
> The work queue is used to queue reset requests like CHANGE-PARAM or
> FAILOVER resets for the worker thread. When the adapter is being
> removed
> the adapter state is set to VNIC_REMOVING and the work queue is
> flushed
> so no new work is added. However the check for adapter being removed
> is
> racy in that the adapter can go into REMOVING state just after we
> check
> and we might end up adding work just as it is being flushed (or
> after).
>
> Use a new spin lock, ->remove_lock to ensure that after (while) the
> work
> queue is (being) flushed, no new work is queued.
>
> A follow-on patch will convert the existing ->state_lock from a spin
> lock
> to to a mutex to allow us to hold it for longer periods of time.
> Since
> work can be scheduled from a tasklet, we cannot block on the mutex,
> so
> use a new spin lock.
>
> Fixes: 6954a9e4192b ("ibmvnic: Flush existing work items before
> device removal")
> Signed-off-by: Sukadev Bhattiprolu <suka...@linux.ibm.com>
> ---
> drivers/net/ethernet/ibm/ibmvnic.c | 15 ++++++++++++++-
> drivers/net/ethernet/ibm/ibmvnic.h | 2 ++
> 2 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c
> b/drivers/net/ethernet/ibm/ibmvnic.c
> index ad551418ac63..7645df37e886 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -2435,6 +2435,7 @@ static int ibmvnic_reset(struct ibmvnic_adapter
> *adapter,
> enum ibmvnic_reset_reason reason)
> {
> struct net_device *netdev = adapter->netdev;
> + unsigned long flags;
> int ret;
>
> if (adapter->state == VNIC_PROBING) {
> @@ -2443,6 +2444,8 @@ static int ibmvnic_reset(struct ibmvnic_adapter
> *adapter,
> goto err;
> }
>
> + spin_lock_irqsave(&adapter->remove_lock, flags);
> +
> /*
> * If failover is pending don't schedule any other reset.
> * Instead let the failover complete. If there is already a
> @@ -2465,8 +2468,9 @@ static int ibmvnic_reset(struct ibmvnic_adapter
> *adapter,
> netdev_dbg(adapter->netdev, "Scheduling reset (reason %d)\n",
> reason);
> schedule_work(&adapter->ibmvnic_reset);
>
> - return 0;
> + ret = 0;
> err:
> + spin_unlock_irqrestore(&adapter->remove_lock, flags);
> return -ret;
> }
>
> @@ -5387,6 +5391,7 @@ static int ibmvnic_probe(struct vio_dev *dev,
> const struct vio_device_id *id)
> memset(&adapter->pending_resets, 0, sizeof(adapter-
> >pending_resets));
> spin_lock_init(&adapter->rwi_lock);
> spin_lock_init(&adapter->state_lock);
> + spin_lock_init(&adapter->remove_lock);
> mutex_init(&adapter->fw_lock);
> init_completion(&adapter->init_done);
> init_completion(&adapter->fw_done);
> @@ -5467,7 +5472,15 @@ static int ibmvnic_remove(struct vio_dev *dev)
> return -EBUSY;
> }
>
> + /* If ibmvnic_reset() is scheduling a reset, wait for it to
> + * finish. Then prevent it from scheduling any more resets
> + * and have the reset functions ignore any resets that have
> + * already been scheduled.
> + */
> + spin_lock_irqsave(&adapter->remove_lock, flags);
> adapter->state = VNIC_REMOVING;
> + spin_unlock_irqrestore(&adapter->remove_lock, flags);
> +
Why irqsave/restore variants ? are you expecting this spinlock to be
held in interruptcontext ?
> spin_unlock_irqrestore(&adapter->state_lock, flags);
>
> flush_work(&adapter->ibmvnic_reset);
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.h
> b/drivers/net/ethernet/ibm/ibmvnic.h
> index 1179a95a3f92..2779696ade09 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.h
> +++ b/drivers/net/ethernet/ibm/ibmvnic.h
> @@ -1081,6 +1081,8 @@ struct ibmvnic_adapter {
> spinlock_t rwi_lock;
> enum ibmvnic_reset_reason pending_resets[VNIC_RESET_MAX-1];
> short next_reset;
> + /* serialize ibmvnic_reset() and ibmvnic_remove() */
> + spinlock_t remove_lock;
> struct work_struct ibmvnic_reset;
> struct delayed_work ibmvnic_delayed_reset;
> unsigned long resetting;
