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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>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.9 21/28] soc/fsl/qbman: fix issue in qman_delete_cgr_safe()
Date:   Thu, 29 Mar 2018 20:00:40 +0200
Message-Id: <20180329175735.853650136@linuxfoundation.org>
In-Reply-To: <20180329175733.447823703@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

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

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


[ Upstream commit 96f413f47677366e0ae03797409bfcc4151dbf9e ]

The wait_for_completion() call in qman_delete_cgr_safe()
was triggering a scheduling while atomic bug, replacing the
kthread with a smp_call_function_single() call to fix it.

Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: Roy Pledge <roy.pledge@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/soc/fsl/qbman/qman.c |   28 +++++-----------------------
 1 file changed, 5 insertions(+), 23 deletions(-)

--- a/drivers/soc/fsl/qbman/qman.c
+++ b/drivers/soc/fsl/qbman/qman.c
@@ -2429,39 +2429,21 @@ struct cgr_comp {
 	struct completion completion;
 };
 
-static int qman_delete_cgr_thread(void *p)
+static void qman_delete_cgr_smp_call(void *p)
 {
-	struct cgr_comp *cgr_comp = (struct cgr_comp *)p;
-	int ret;
-
-	ret = qman_delete_cgr(cgr_comp->cgr);
-	complete(&cgr_comp->completion);
-
-	return ret;
+	qman_delete_cgr((struct qman_cgr *)p);
 }
 
 void qman_delete_cgr_safe(struct qman_cgr *cgr)
 {
-	struct task_struct *thread;
-	struct cgr_comp cgr_comp;
-
 	preempt_disable();
 	if (qman_cgr_cpus[cgr->cgrid] != smp_processor_id()) {
-		init_completion(&cgr_comp.completion);
-		cgr_comp.cgr = cgr;
-		thread = kthread_create(qman_delete_cgr_thread, &cgr_comp,
-					"cgr_del");
-
-		if (IS_ERR(thread))
-			goto out;
-
-		kthread_bind(thread, qman_cgr_cpus[cgr->cgrid]);
-		wake_up_process(thread);
-		wait_for_completion(&cgr_comp.completion);
+		smp_call_function_single(qman_cgr_cpus[cgr->cgrid],
+					 qman_delete_cgr_smp_call, cgr, true);
 		preempt_enable();
 		return;
 	}
-out:
+
 	qman_delete_cgr(cgr);
 	preempt_enable();
 }