netdev - [PATCH net-next 2/3] i40e: Remove unnecessary synchronize_irq() before free

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Date:   Tue, 21 Jun 2022 15:59:29 -0700
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Minghao Chi <chi.minghao@....com.cn>, netdev@...r.kernel.org,
        anthony.l.nguyen@...el.com, sassmann@...hat.com,
        Zeal Robot <zealci@....com.cn>,
        Gurucharan <gurucharanx.g@...el.com>
Subject: [PATCH net-next 2/3] 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>
Tested-by: Gurucharan <gurucharanx.g@...el.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 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 83e0cf475ebd..797f61b2cd96 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -4162,7 +4162,6 @@ 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);
 	}
@@ -4901,7 +4900,6 @@ 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
-- 
2.35.1