From: Roy Novich <royno@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: Roy Novich <royno@xxxxxxxxxx>
Reviewed-by: Moshe Shemesh <moshe@xxxxxxxxxx>
Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.35.1
