linux-kernel - [PATCH] i40e: Remove unnecessary synchronize_irq() before free

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Date:   Mon, 16 May 2022 07:27:17 +0000
From:   cgel.zte@...il.com
To:     jesse.brandeburg@...el.com
Cc:     anthony.l.nguyen@...el.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Minghao Chi <chi.minghao@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: [PATCH] i40e: Remove unnecessary synchronize_irq() before free_irq()

From: Minghao Chi <chi.minghao@....com.cn>

Calling synchronize_irq() right before free_irq() is quite useless. On one
hand the IRQ can easily fire again before free_irq() is entered, on the
other hand free_irq() itself calls synchronize_irq() internally (in a race
condition free way), before any state associated with the IRQ is freed.

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Minghao Chi <chi.minghao@....com.cn>
---
 drivers/net/ethernet/intel/i40e/i40e_main.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 332a608dbaa6..2b654a53a3f0 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -4037,7 +4037,6 @@ static void i40e_free_misc_vector(struct i40e_pf *pf)
 	i40e_flush(&pf->hw);
 
 	if (pf->flags & I40E_FLAG_MSIX_ENABLED && pf->msix_entries) {
-		synchronize_irq(pf->msix_entries[0].vector);
 		free_irq(pf->msix_entries[0].vector, pf);
 		clear_bit(__I40E_MISC_IRQ_REQUESTED, pf->state);
 	}
@@ -4776,7 +4775,6 @@ static void i40e_vsi_free_irq(struct i40e_vsi *vsi)
 			irq_set_affinity_notifier(irq_num, NULL);
 			/* remove our suggested affinity mask for this IRQ */
 			irq_update_affinity_hint(irq_num, NULL);
-			synchronize_irq(irq_num);
 			free_irq(irq_num, vsi->q_vectors[i]);
 
 			/* Tear down the interrupt queue link list
-- 
2.25.1