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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Madalin Bucur <madalin.bucur@nxp.com>,
        Roy Pledge <roy.pledge@nxp.com>, Li Yang <leoyang.li@nxp.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.20 082/171] soc: fsl: qbman: avoid race in clearing QMan interrupt
Date:   Tue, 12 Mar 2019 10:07:42 -0700
Message-Id: <20190312170355.108075771@linuxfoundation.org>
In-Reply-To: <20190312170347.868927101@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ 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@nxp.com>
Signed-off-by: Roy Pledge <roy.pledge@nxp.com>
Signed-off-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Sasha Levin <sashal@kernel.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 5ce24718c2fd..d8b3ba047c28 100644
--- a/drivers/soc/fsl/qbman/qman.c
+++ b/drivers/soc/fsl/qbman/qman.c
@@ -1124,18 +1124,19 @@ 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