From: Roy Novich royno@nvidia.com
[ Upstream commit 2808b37b59288ad8f1897e3546c2296df3384b65 ]
For a single CPU system, the kernel thread executing mlx5_cmd_flush() never releases the CPU but calls down_trylock(&cmd→sem) in a busy loop. On a single processor system, this leads to a deadlock as the kernel thread which executes mlx5_cmd_invoke() never gets scheduled. Fix this, by adding the cond_resched() call to the loop, allow the command completion kernel thread to execute.
Fixes: 8e715cd613a1 ("net/mlx5: Set command entry semaphore up once got index free") Signed-off-by: Alexander Schmidt alexschm@de.ibm.com Signed-off-by: Roy Novich royno@nvidia.com Reviewed-by: Moshe Shemesh moshe@nvidia.com Signed-off-by: Saeed Mahameed saeedm@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/cmd.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c index 4fdc97304f69..e00a8eb7716f 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c @@ -1682,12 +1682,17 @@ void mlx5_cmd_flush(struct mlx5_core_dev *dev) struct mlx5_cmd *cmd = &dev->cmd; int i;
- for (i = 0; i < cmd->max_reg_cmds; i++) - while (down_trylock(&cmd->sem)) + for (i = 0; i < cmd->max_reg_cmds; i++) { + while (down_trylock(&cmd->sem)) { mlx5_cmd_trigger_completions(dev); + cond_resched(); + } + }
- while (down_trylock(&cmd->pages_sem)) + while (down_trylock(&cmd->pages_sem)) { mlx5_cmd_trigger_completions(dev); + cond_resched(); + }
/* Unlock cmdif */ up(&cmd->pages_sem);