netdev - [patch 22/30] net/mlx5: Replace irq_to

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Date:   Thu, 10 Dec 2020 20:25:58 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Marc Zyngier <maz@...nel.org>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>,
        afzal mohammed <afzal.mohd.ma@...il.com>,
        linux-parisc@...r.kernel.org, Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>, linux-s390@...r.kernel.org,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
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        linux-rdma@...r.kernel.org, Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xenproject.org
Subject: [patch 22/30] net/mlx5: Replace irq_to_desc() abuse

No driver has any business with the internals of an interrupt
descriptor. Storing a pointer to it just to use yet another helper at the
actual usage site to retrieve the affinity mask is creative at best. Just
because C does not allow encapsulation does not mean that the kernel has no
limits.

Retrieve a pointer to the affinity mask itself and use that. It's still
using an interface which is usually not for random drivers, but definitely
less hideous than the previous hack.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/en.h      |    2 +-
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c |    2 +-
 drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c |    6 +-----
 3 files changed, 3 insertions(+), 7 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -669,7 +669,7 @@ struct mlx5e_channel {
 	spinlock_t                 async_icosq_lock;
 
 	/* data path - accessed per napi poll */
-	struct irq_desc *irq_desc;
+	const struct cpumask	  *aff_mask;
 	struct mlx5e_ch_stats     *stats;
 
 	/* control */
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -1998,7 +1998,7 @@ static int mlx5e_open_channel(struct mlx
 	c->num_tc   = params->num_tc;
 	c->xdp      = !!params->xdp_prog;
 	c->stats    = &priv->channel_stats[ix].ch;
-	c->irq_desc = irq_to_desc(irq);
+	c->aff_mask = irq_get_affinity_mask(irq);
 	c->lag_port = mlx5e_enumerate_lag_port(priv->mdev, ix);
 
 	netif_napi_add(netdev, &c->napi, mlx5e_napi_poll, 64);
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c
@@ -40,12 +40,8 @@
 static inline bool mlx5e_channel_no_affinity_change(struct mlx5e_channel *c)
 {
 	int current_cpu = smp_processor_id();
-	const struct cpumask *aff;
-	struct irq_data *idata;
 
-	idata = irq_desc_get_irq_data(c->irq_desc);
-	aff = irq_data_get_affinity_mask(idata);
-	return cpumask_test_cpu(current_cpu, aff);
+	return cpumask_test_cpu(current_cpu, c->aff_mask);
 }
 
 static void mlx5e_handle_tx_dim(struct mlx5e_txqsq *sq)