Patch "net/mlx5: Allow async trigger completion execution on single CPU systems" has been added to the 6.0-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net/mlx5: Allow async trigger completion execution on single CPU systems

to the 6.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-mlx5-allow-async-trigger-completion-execution-on.patch
and it can be found in the queue-6.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0e296e7cdcae169ae33cf6d54ba449592416c8d3
Author: Roy Novich <royno@xxxxxxxxxx>
Date:   Wed Nov 2 23:55:38 2022 -0700

    net/mlx5: Allow async trigger completion execution on single CPU systems
    
    [ 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>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
index 46ba4c2faad2..2e0d59ca62b5 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
@@ -1770,12 +1770,17 @@ 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);