netdev - Re: [PATCH net-next] mlx4: do not fire tasklet unless necessary

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Message-ID: <1487385969.1311.91.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Fri, 17 Feb 2017 18:46:09 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Saeed Mahameed <saeedm@....mellanox.co.il>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: Re: [PATCH net-next] mlx4: do not fire tasklet unless necessary

On Thu, 2017-02-16 at 07:30 -0800, Eric Dumazet wrote:
> On Thu, 2017-02-16 at 14:38 +0200, Saeed Mahameed wrote:
> 
> > Acked-by: Saeed Mahameed <saeedm@...lanox.com>
> 
> Thanks for reviewing this Saeed !

Note that mlx4_add_cq_to_tasklet() is called from hard irq context, so
we could replace the spin_lock_irqsave() by spin_lock()

Not that I care, but you might be interested ;)

Thanks.

diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c
index fa6d2354a0e910ee160863e3cbe21a512d77bf03..9dcac3a367425f2804e933842698c66685baf626 100644
--- a/drivers/net/ethernet/mellanox/mlx4/cq.c
+++ b/drivers/net/ethernet/mellanox/mlx4/cq.c
@@ -79,13 +79,13 @@ void mlx4_cq_tasklet_cb(unsigned long data)
 		tasklet_schedule(&ctx->task);
 }
 
+/* Called from hard irq handler */
 static void mlx4_add_cq_to_tasklet(struct mlx4_cq *cq)
 {
 	struct mlx4_eq_tasklet *tasklet_ctx = cq->tasklet_ctx.priv;
-	unsigned long flags;
 	bool kick;
 
-	spin_lock_irqsave(&tasklet_ctx->lock, flags);
+	spin_lock(&tasklet_ctx->lock);
 	/* When migrating CQs between EQs will be implemented, please note
 	 * that you need to sync this point. It is possible that
 	 * while migrating a CQ, completions on the old EQs could
@@ -98,7 +98,7 @@ static void mlx4_add_cq_to_tasklet(struct mlx4_cq *cq)
 		if (kick)
 			tasklet_schedule(&tasklet_ctx->task);
 	}
-	spin_unlock_irqrestore(&tasklet_ctx->lock, flags);
+	spin_unlock(&tasklet_ctx->lock);
 }
 
 void mlx4_cq_completion(struct mlx4_dev *dev, u32 cqn)