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net/mlx4_core: Fix deadlock when switching between polling and event fw commands
When switching from polling-based fw commands to event-based fw
commands, there is a race condition which could cause a fw command
in another task to hang: that task will keep waiting for the polling
sempahore, but may never be able to acquire it. This is due to
mlx4_cmd_use_events, which "down"s the sempahore back to 0.
During driver initialization, this is not a problem, since no other
tasks which invoke FW commands are active.
However, there is a problem if the driver switches to polling mode
and then back to event mode during normal operation.
The "test_interrupts" feature does exactly that.
Running "ethtool -t <eth device> offline" causes the PF driver to
temporarily switch to polling mode, and then back to event mode.
(Note that for VF drivers, such switching is not performed).
Fix this by adding a read-write semaphore for protection when
switching between modes.
Fixes: 225c7b1fee
("IB/mlx4: Add a driver Mellanox ConnectX InfiniBand adapters")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
30353bfc43
commit
a7e1f04905
@ -785,17 +785,23 @@ int __mlx4_cmd(struct mlx4_dev *dev, u64 in_param, u64 *out_param,
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return mlx4_cmd_reset_flow(dev, op, op_modifier, -EIO);
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if (!mlx4_is_mfunc(dev) || (native && mlx4_is_master(dev))) {
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int ret;
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if (dev->persist->state & MLX4_DEVICE_STATE_INTERNAL_ERROR)
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return mlx4_internal_err_ret_value(dev, op,
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op_modifier);
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down_read(&mlx4_priv(dev)->cmd.switch_sem);
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if (mlx4_priv(dev)->cmd.use_events)
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return mlx4_cmd_wait(dev, in_param, out_param,
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out_is_imm, in_modifier,
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op_modifier, op, timeout);
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ret = mlx4_cmd_wait(dev, in_param, out_param,
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out_is_imm, in_modifier,
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op_modifier, op, timeout);
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else
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return mlx4_cmd_poll(dev, in_param, out_param,
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out_is_imm, in_modifier,
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op_modifier, op, timeout);
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ret = mlx4_cmd_poll(dev, in_param, out_param,
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out_is_imm, in_modifier,
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op_modifier, op, timeout);
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up_read(&mlx4_priv(dev)->cmd.switch_sem);
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return ret;
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}
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return mlx4_slave_cmd(dev, in_param, out_param, out_is_imm,
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in_modifier, op_modifier, op, timeout);
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@ -2454,6 +2460,7 @@ int mlx4_cmd_init(struct mlx4_dev *dev)
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int flags = 0;
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if (!priv->cmd.initialized) {
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init_rwsem(&priv->cmd.switch_sem);
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mutex_init(&priv->cmd.slave_cmd_mutex);
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sema_init(&priv->cmd.poll_sem, 1);
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priv->cmd.use_events = 0;
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@ -2583,6 +2590,7 @@ int mlx4_cmd_use_events(struct mlx4_dev *dev)
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if (!priv->cmd.context)
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return -ENOMEM;
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down_write(&priv->cmd.switch_sem);
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for (i = 0; i < priv->cmd.max_cmds; ++i) {
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priv->cmd.context[i].token = i;
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priv->cmd.context[i].next = i + 1;
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@ -2606,6 +2614,7 @@ int mlx4_cmd_use_events(struct mlx4_dev *dev)
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down(&priv->cmd.poll_sem);
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priv->cmd.use_events = 1;
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up_write(&priv->cmd.switch_sem);
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return err;
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}
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@ -2618,6 +2627,7 @@ void mlx4_cmd_use_polling(struct mlx4_dev *dev)
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struct mlx4_priv *priv = mlx4_priv(dev);
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int i;
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down_write(&priv->cmd.switch_sem);
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priv->cmd.use_events = 0;
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for (i = 0; i < priv->cmd.max_cmds; ++i)
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@ -2626,6 +2636,7 @@ void mlx4_cmd_use_polling(struct mlx4_dev *dev)
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kfree(priv->cmd.context);
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up(&priv->cmd.poll_sem);
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up_write(&priv->cmd.switch_sem);
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}
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struct mlx4_cmd_mailbox *mlx4_alloc_cmd_mailbox(struct mlx4_dev *dev)
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@ -46,6 +46,7 @@
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#include <linux/interrupt.h>
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#include <linux/spinlock.h>
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#include <net/devlink.h>
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#include <linux/rwsem.h>
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#include <linux/mlx4/device.h>
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#include <linux/mlx4/driver.h>
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@ -627,6 +628,7 @@ struct mlx4_cmd {
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struct mutex slave_cmd_mutex;
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struct semaphore poll_sem;
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struct semaphore event_sem;
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struct rw_semaphore switch_sem;
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int max_cmds;
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spinlock_t context_lock;
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int free_head;
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