linux-kernel - [PATCH AUTOSEL 4.19 10/64] soc: fsl: qbman: avoid race in clearing QMan interrupt

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Date:   Thu, 28 Feb 2019 10:10:11 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Madalin Bucur <madalin.bucur@....com>,
        Roy Pledge <roy.pledge@....com>, Li Yang <leoyang.li@....com>,
        Sasha Levin <sashal@...nel.org>, linuxppc-dev@...ts.ozlabs.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH AUTOSEL 4.19 10/64] soc: fsl: qbman: avoid race in clearing QMan interrupt

From: Madalin Bucur <madalin.bucur@....com>

[ Upstream commit 89857a8a5c89a406b967ab2be7bd2ccdbe75e73d ]

By clearing all interrupt sources, not only those that
already occurred, the existing code may acknowledge by
mistake interrupts that occurred after the code checks
for them.

Signed-off-by: Madalin Bucur <madalin.bucur@....com>
Signed-off-by: Roy Pledge <roy.pledge@....com>
Signed-off-by: Li Yang <leoyang.li@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/soc/fsl/qbman/qman.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/fsl/qbman/qman.c b/drivers/soc/fsl/qbman/qman.c
index 8cc0151830433..a4ac6073c555d 100644
--- a/drivers/soc/fsl/qbman/qman.c
+++ b/drivers/soc/fsl/qbman/qman.c
@@ -1081,18 +1081,19 @@ static void qm_mr_process_task(struct work_struct *work);
 static irqreturn_t portal_isr(int irq, void *ptr)
 {
 	struct qman_portal *p = ptr;
-
-	u32 clear = QM_DQAVAIL_MASK | p->irq_sources;
 	u32 is = qm_in(&p->p, QM_REG_ISR) & p->irq_sources;
+	u32 clear = 0;
 
 	if (unlikely(!is))
 		return IRQ_NONE;
 
 	/* DQRR-handling if it's interrupt-driven */
-	if (is & QM_PIRQ_DQRI)
+	if (is & QM_PIRQ_DQRI) {
 		__poll_portal_fast(p, QMAN_POLL_LIMIT);
+		clear = QM_DQAVAIL_MASK | QM_PIRQ_DQRI;
+	}
 	/* Handling of anything else that's interrupt-driven */
-	clear |= __poll_portal_slow(p, is);
+	clear |= __poll_portal_slow(p, is) & QM_PIRQ_SLOW;
 	qm_out(&p->p, QM_REG_ISR, clear);
 	return IRQ_HANDLED;
 }
-- 
2.19.1