Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Julian Wiedmann <jwi@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>
Subject: [PATCH 4.19 39/47] s390/qdio: dont touch the dsci in tiqdio_add_input_queues()
Date:   Thu, 18 Jul 2019 12:01:53 +0900
Message-Id: <20190718030052.060549614@linuxfoundation.org>
In-Reply-To: <20190718030045.780672747@linuxfoundation.org>
References: <20190718030045.780672747@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Julian Wiedmann <jwi@linux.ibm.com>

commit ac6639cd3db607d386616487902b4cc1850a7be5 upstream.

Current code sets the dsci to 0x00000080. Which doesn't make any sense,
as the indicator area is located in the _left-most_ byte.

Worse: if the dsci is the _shared_ indicator, this potentially clears
the indication of activity for a _different_ device.
tiqdio_thinint_handler() will then have no reason to call that device's
IRQ handler, and the device ends up stalling.

Fixes: d0c9d4a89fff ("[S390] qdio: set correct bit in dsci")
Cc: <stable@vger.kernel.org>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/s390/cio/qdio_thinint.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -79,7 +79,6 @@ void tiqdio_add_input_queues(struct qdio
 	mutex_lock(&tiq_list_lock);
 	list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
 	mutex_unlock(&tiq_list_lock);
-	xchg(irq_ptr->dsci, 1 << 7);
 }
 
 void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)