linux-kernel - RE: [PATCH] qla3xxx: Ensure request/response queue addr writes to the registers

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Date:	Fri, 19 Oct 2012 10:12:25 -0700
From:	Jitendra Kalsaria <jitendra.kalsaria@...gic.com>
To:	Joe Jin <joe.jin@...cle.com>, Ron Mercer <ron.mercer@...gic.com>,
	Dept-Eng Linux Driver <Linux-Driver@...gic.com>
CC:	netdev <netdev@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Greg Marsden <greg.marsden@...cle.com>
Subject: RE: [PATCH] qla3xxx: Ensure request/response queue addr writes to
 the registers



>From: Joe Jin [mailto:joe.jin@...cle.com] 
>Sent: Thursday, October 18, 2012 6:25 PM
>To: Ron Mercer; Dept-Eng Linux Driver; Jitendra Kalsaria; Joe Jin
>Cc: netdev; linux-kernel; Greg Marsden
>Subject: [PATCH] qla3xxx: Ensure request/response queue addr writes to the registers
>
>Before use the request and response queue addr, make sure it has wrote
>to the registers.
>
>Signed-off-by: Joe Jin <joe.jin@...cle.com>
>Cc: Jitendra Kalsaria <jitendra.kalsaria@...gic.com>
>Cc: Ron Mercer <ron.mercer@...gic.com>
>---
> drivers/net/ethernet/qlogic/qla3xxx.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/drivers/net/ethernet/qlogic/qla3xxx.c b/drivers/net/ethernet/qlogic/qla3xxx.c
>index df09b1c..f745ade 100644
>--- a/drivers/net/ethernet/qlogic/qla3xxx.c
>+++ b/drivers/net/ethernet/qlogic/qla3xxx.c
>@@ -2525,6 +2525,12 @@ static int ql_alloc_net_req_rsp_queues(struct ql3_adapter *qdev)
> 	qdev->req_q_size =
> 	    (u32) (NUM_REQ_Q_ENTRIES * sizeof(struct ob_mac_iocb_req));
> 
>+	/*
>+	 * The barrier is required to ensure request and response queue
>+	 * addr writes to the registers.
>+	 */
>+	wmb();
>+
> 	qdev->req_q_virt_addr =
> 	    pci_alloc_consistent(qdev->pdev,
> 				 (size_t) qdev->req_q_size,

Joe,

You need to move below line above the write memory barrier to get response queue address write to register
	qdev->rsp_q_size = NUM_RSP_Q_ENTRIES * sizeof(struct net_rsp_iocb);

Your patch will be like below:
<snip>
	qdev->req_q_size =
		(u32) (NUM_REQ_Q_ENTRIES * sizeof(struct ob_mac_iocb_req));

+	qdev->rsp_q_size = NUM_RSP_Q_ENTRIES * sizeof(struct net_rsp_iocb);
+
+	/*
+	 * The barrier is required to ensure request and response queue
+	 * addr writes to the registers.
+	 */
+	wmb();
+

<\snip>


thanks,
	Jiten
-- 
1.7.11.7



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