qed: fix qed_fill_link() error handling

gcc warns about qed_fill_link possibly accessing uninitialized data:

drivers/net/ethernet/qlogic/qed/qed_main.c: In function 'qed_fill_link':
drivers/net/ethernet/qlogic/qed/qed_main.c:1170:35: error: 'link_caps' may be used uninitialized in this function [-Werror=maybe-uninitialized]

While this warning is only about the specific case of CONFIG_QED_SRIOV
being disabled but the function getting called for a VF (which should
never happen), another possibility is that qed_mcp_get_*() fails without
returning data.

This rearranges the code so we bail out in either of the two cases
and print a warning instead of accessing the uninitialized data.

The qed_link_output structure remains untouched in this case, but
all callers first call memset() on it, so at least we are not leaking
stack data then.

As discussed, we also use a compile-time check to ensure we never
use any of the VF code if CONFIG_QED_SRIOV is disabled, and the
PCI device table is updated to no longer bind to virtual functions
in that configuration.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qed/qed_main.c

@@ -1105,6 +1105,39 @@ static int qed_get_port_type(u32 media_type)
 	return port_type;
 }
 
+static int qed_get_link_data(struct qed_hwfn *hwfn,
+			     struct qed_mcp_link_params *params,
+			     struct qed_mcp_link_state *link,
+			     struct qed_mcp_link_capabilities *link_caps)
+{
+	void *p;
+
+	if (!IS_PF(hwfn->cdev)) {
+		qed_vf_get_link_params(hwfn, params);
+		qed_vf_get_link_state(hwfn, link);
+		qed_vf_get_link_caps(hwfn, link_caps);
+
+		return 0;
+	}
+
+	p = qed_mcp_get_link_params(hwfn);
+	if (!p)
+		return -ENXIO;
+	memcpy(params, p, sizeof(*params));
+
+	p = qed_mcp_get_link_state(hwfn);
+	if (!p)
+		return -ENXIO;
+	memcpy(link, p, sizeof(*link));
+
+	p = qed_mcp_get_link_capabilities(hwfn);
+	if (!p)
+		return -ENXIO;
+	memcpy(link_caps, p, sizeof(*link_caps));
+
+	return 0;
+}
+
 static void qed_fill_link(struct qed_hwfn *hwfn,
 			  struct qed_link_output *if_link)
 {
@@ -1116,15 +1149,9 @@ static void qed_fill_link(struct qed_hwfn *hwfn,
 	memset(if_link, 0, sizeof(*if_link));
 
 	/* Prepare source inputs */
-	if (IS_PF(hwfn->cdev)) {
-		memcpy(&params, qed_mcp_get_link_params(hwfn), sizeof(params));
-		memcpy(&link, qed_mcp_get_link_state(hwfn), sizeof(link));
-		memcpy(&link_caps, qed_mcp_get_link_capabilities(hwfn),
-		       sizeof(link_caps));
-	} else {
-		qed_vf_get_link_params(hwfn, &params);
-		qed_vf_get_link_state(hwfn, &link);
-		qed_vf_get_link_caps(hwfn, &link_caps);
+	if (qed_get_link_data(hwfn, &params, &link, &link_caps)) {
+		dev_warn(&hwfn->cdev->pdev->dev, "no link data available\n");
+		return;
 	}
 
 	/* Set the link parameters to pass to protocol driver */

drivers/net/ethernet/qlogic/qed/qed_sriov.h

@@ -12,11 +12,13 @@
 #include "qed_vf.h"
 #define QED_VF_ARRAY_LENGTH (3)
 
+#ifdef CONFIG_QED_SRIOV
 #define IS_VF(cdev)             ((cdev)->b_is_vf)
 #define IS_PF(cdev)             (!((cdev)->b_is_vf))
-#ifdef CONFIG_QED_SRIOV
 #define IS_PF_SRIOV(p_hwfn)     (!!((p_hwfn)->cdev->p_iov_info))
 #else
+#define IS_VF(cdev)             (0)
+#define IS_PF(cdev)             (1)
 #define IS_PF_SRIOV(p_hwfn)     (0)
 #endif
 #define IS_PF_SRIOV_ALLOC(p_hwfn)       (!!((p_hwfn)->pf_iov_info))

drivers/net/ethernet/qlogic/qede/qede_main.c

@@ -87,7 +87,9 @@ static const struct pci_device_id qede_pci_tbl[] = {
 	{PCI_VDEVICE(QLOGIC, PCI_DEVICE_ID_57980S_100), QEDE_PRIVATE_PF},
 	{PCI_VDEVICE(QLOGIC, PCI_DEVICE_ID_57980S_50), QEDE_PRIVATE_PF},
 	{PCI_VDEVICE(QLOGIC, PCI_DEVICE_ID_57980S_25), QEDE_PRIVATE_PF},
+#ifdef CONFIG_QED_SRIOV
 	{PCI_VDEVICE(QLOGIC, PCI_DEVICE_ID_57980S_IOV), QEDE_PRIVATE_VF},
+#endif
 	{ 0 }
 };