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From:   Madalin Bucur <madalin.bucur@nxp.com>
To:     leoyang.li@nxp.com, linux-arm-kernel@lists.infradead.org
Cc:     roy.pledge@nxp.com, davem@davemloft.net,
        linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Madalin Bucur <madalin.bucur@nxp.com>
Subject: [PATCH] soc: fsl: qbman: avoid race in clearing QMan interrupt
Date:   Fri, 21 Dec 2018 16:41:42 +0200
Message-Id: <1545403302-22475-1-git-send-email-madalin.bucur@nxp.com>
Reply-to: madalin.bucur@nxp.com
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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>
---
 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 52c153cd795a..636f83f781f5 100644
--- a/drivers/soc/fsl/qbman/qman.c
+++ b/drivers/soc/fsl/qbman/qman.c
@@ -1143,18 +1143,19 @@ 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;
 }
-- 
2.1.0