qed*: Fix link indication race

Driver changes the link properties via communication with
the management firmware, and re-reads the resulting link status
when it receives an indication that the link has changed.
However, there are certain scenarios where such indications
might be missing, and so driver also re-reads the current link
results without attention in several places. Specifically, it
does so during load and when resetting the link.

This creates a race where driver might reflect incorrect
link status - e.g., when explicit reading of the link status is
switched by attention with the changed configuration.

Correct this flow by a lock syncronizing the handling of the
link indications [both explicit requests and attention].

Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 33 insertions, 12 deletions

diff --git a/drivers/net/ethernet/qlogic/qed/qed_main.c b/drivers/net/ethernet/qlogic/qed/qed_main.c
index 4440ae7ec85b..eef30a598b40 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_main.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_main.c
@@ -1146,12 +1146,18 @@ static int qed_set_link(struct qed_dev *cdev, struct qed_link_params *params)
 	if (!cdev)
 		return -ENODEV;
 
-	if (IS_VF(cdev))
-		return 0;
-
 	/* The link should be set only once per PF */
 	hwfn = &cdev->hwfns[0];
 
+	/* When VF wants to set link, force it to read the bulletin instead.
+	 * This mimics the PF behavior, where a noitification [both immediate
+	 * and possible later] would be generated when changing properties.
+	 */
+	if (IS_VF(cdev)) {
+		qed_schedule_iov(hwfn, QED_IOV_WQ_VF_FORCE_LINK_QUERY_FLAG);
+		return 0;
+	}
+
 	ptt = qed_ptt_acquire(hwfn);
 	if (!ptt)
 		return -EBUSY;
diff --git a/drivers/net/ethernet/qlogic/qed/qed_mcp.c b/drivers/net/ethernet/qlogic/qed/qed_mcp.c
index 7624a38cbd39..314022df3469 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_mcp.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_mcp.c
@@ -192,6 +192,7 @@ int qed_mcp_cmd_init(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt)
 
 	/* Initialize the MFW spinlock */
 	spin_lock_init(&p_info->lock);
+	spin_lock_init(&p_info->link_lock);
 
 	return 0;
 
@@ -610,6 +611,9 @@ static void qed_mcp_handle_link_change(struct qed_hwfn *p_hwfn,
 	u8 max_bw, min_bw;
 	u32 status = 0;
 
+	/* Prevent SW/attentions from doing this at the same time */
+	spin_lock_bh(&p_hwfn->mcp_info->link_lock);
+
 	p_link = &p_hwfn->mcp_info->link_output;
 	memset(p_link, 0, sizeof(*p_link));
 	if (!b_reset) {
@@ -624,7 +628,7 @@ static void qed_mcp_handle_link_change(struct qed_hwfn *p_hwfn,
 	} else {
 		DP_VERBOSE(p_hwfn, NETIF_MSG_LINK,
 			   "Resetting link indications\n");
-		return;
+		goto out;
 	}
 
 	if (p_hwfn->b_drv_link_init)
@@ -731,6 +735,8 @@ static void qed_mcp_handle_link_change(struct qed_hwfn *p_hwfn,
 	p_link->sfp_tx_fault = !!(status & LINK_STATUS_SFP_TX_FAULT);
 
 	qed_link_update(p_hwfn);
+out:
+	spin_unlock_bh(&p_hwfn->mcp_info->link_lock);
 }
 
 int qed_mcp_set_link(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt, bool b_up)
@@ -780,9 +786,13 @@ int qed_mcp_set_link(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt, bool b_up)
 		return rc;
 	}
 
-	/* Reset the link status if needed */
-	if (!b_up)
-		qed_mcp_handle_link_change(p_hwfn, p_ptt, true);
+	/* Mimic link-change attention, done for several reasons:
+	 *  - On reset, there's no guarantee MFW would trigger
+	 *    an attention.
+	 *  - On initialization, older MFWs might not indicate link change
+	 *    during LFA, so we'll never get an UP indication.
+	 */
+	qed_mcp_handle_link_change(p_hwfn, p_ptt, !b_up);
 
 	return 0;
 }
diff --git a/drivers/net/ethernet/qlogic/qed/qed_mcp.h b/drivers/net/ethernet/qlogic/qed/qed_mcp.h
index 0792224ac219..368e88de146c 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_mcp.h
+++ b/drivers/net/ethernet/qlogic/qed/qed_mcp.h
@@ -485,7 +485,13 @@ int qed_mcp_bist_nvm_test_get_image_att(struct qed_hwfn *p_hwfn,
 #define MFW_PORT(_p_hwfn)       ((_p_hwfn)->abs_pf_id %	\
 				 ((_p_hwfn)->cdev->num_ports_in_engines * 2))
 struct qed_mcp_info {
+	/* Spinlock used for protecting the access to the MFW mailbox */
 	spinlock_t				lock;
+
+	/* Spinlock used for syncing SW link-changes and link-changes
+	 * originating from attention context.
+	 */
+	spinlock_t				link_lock;
 	bool					block_mb_sending;
 	u32					public_base;
 	u32					drv_mb_addr;
diff --git a/drivers/net/ethernet/qlogic/qed/qed_sriov.h b/drivers/net/ethernet/qlogic/qed/qed_sriov.h
index 0a2e3a36d2cf..fc08cc2da6a7 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_sriov.h
+++ b/drivers/net/ethernet/qlogic/qed/qed_sriov.h
@@ -254,6 +254,7 @@ enum qed_iov_wq_flag {
 	QED_IOV_WQ_STOP_WQ_FLAG,
 	QED_IOV_WQ_FLR_FLAG,
 	QED_IOV_WQ_TRUST_FLAG,
+	QED_IOV_WQ_VF_FORCE_LINK_QUERY_FLAG,
 };
 
 #ifdef CONFIG_QED_SRIOV
diff --git a/drivers/net/ethernet/qlogic/qed/qed_vf.c b/drivers/net/ethernet/qlogic/qed/qed_vf.c
index 9667059b15bd..15d2855ec563 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_vf.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_vf.c
@@ -1285,6 +1285,9 @@ void qed_iov_vf_task(struct work_struct *work)
 
 	/* Handle bulletin board changes */
 	qed_vf_read_bulletin(hwfn, &change);
+	if (test_and_clear_bit(QED_IOV_WQ_VF_FORCE_LINK_QUERY_FLAG,
+			       &hwfn->iov_task_flags))
+		change = 1;
 	if (change)
 		qed_handle_bulletin_change(hwfn);
 
diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c b/drivers/net/ethernet/qlogic/qede/qede_main.c
index 88453ed1a5bf..3a78c3f25157 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_main.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_main.c
@@ -1872,7 +1872,6 @@ static int qede_load(struct qede_dev *edev, enum qede_load_mode mode,
 		     bool is_locked)
 {
 	struct qed_link_params link_params;
-	struct qed_link_output link_output;
 	int rc;
 
 	DP_INFO(edev, "Starting qede load\n");
@@ -1924,11 +1923,7 @@ static int qede_load(struct qede_dev *edev, enum qede_load_mode mode,
 	link_params.link_up = true;
 	edev->ops->common->set_link(edev->cdev, &link_params);
 
-	/* Query whether link is already-up */
-	memset(&link_output, 0, sizeof(link_output));
-	edev->ops->common->get_link(edev->cdev, &link_output);
 	qede_roce_dev_event_open(edev);
-	qede_link_update(edev, &link_output);
 
 	qede_ptp_start(edev, (mode == QEDE_LOAD_NORMAL));