From 58a3de0592454c216c68427fa3c31a34823f5115 Mon Sep 17 00:00:00 2001 From: Eugenia Emantayev Date: Sun, 18 Mar 2012 04:32:08 +0000 Subject: [PATCH] mlx4_core: fix race on comm channel Prevent race condition between commands on comm channel. Happened while unloading the driver when switching from event to polling mode. VF got completion on the last command before switching to polling mode, but toggle was not changed. After the fix - VF will not write the next command before toggle is updated. Signed-off-by: Eugenia Emantayev Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx4/cmd.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlx4/cmd.c b/drivers/net/ethernet/mellanox/mlx4/cmd.c index 48d5c48d7ce8..773c70ea3f62 100644 --- a/drivers/net/ethernet/mellanox/mlx4/cmd.c +++ b/drivers/net/ethernet/mellanox/mlx4/cmd.c @@ -239,6 +239,7 @@ static int mlx4_comm_cmd_wait(struct mlx4_dev *dev, u8 op, { struct mlx4_cmd *cmd = &mlx4_priv(dev)->cmd; struct mlx4_cmd_context *context; + unsigned long end; int err = 0; down(&cmd->event_sem); @@ -268,6 +269,14 @@ static int mlx4_comm_cmd_wait(struct mlx4_dev *dev, u8 op, } out: + /* wait for comm channel ready + * this is necessary for prevention the race + * when switching between event to polling mode + */ + end = msecs_to_jiffies(timeout) + jiffies; + while (comm_pending(dev) && time_before(jiffies, end)) + cond_resched(); + spin_lock(&cmd->context_lock); context->next = cmd->free_head; cmd->free_head = context - cmd->context; -- 2.20.1