[PATCH] net/cxgbe: fix dangling pointer for gcc12

[Ferruh Yigit <ferruh.yigit@intel.com>]

Observed with: gcc (GCC) 12.0.0 20220116 (experimental)

In file included from ../lib/eal/linux/include/rte_os.h:14,
                 from ../lib/eal/include/rte_common.h:28,
                 from ../lib/eal/include/rte_log.h:25,
                 from ../lib/ethdev/rte_ethdev.h:164,
                 from ../lib/ethdev/ethdev_driver.h:18,
                 from ../drivers/net/cxgbe/base/t4vf_hw.c:6:
In function ‘t4_os_atomic_add_tail’,
    inlined from ‘t4vf_wr_mbox_core’ at ../drivers/net/cxgbe/base/t4vf_hw.c:115:2:
../drivers/net/cxgbe/base/adapter.h:742:9: error: storing the address of local variable ‘entry’ in ‘((struct mbox_list *)adapter)[96].tqh_last’ [-Werror=dangling-pointer=]
  742 |         TAILQ_INSERT_TAIL(head, entry, next);
      |         ^~~~~~~~~~~~~~~~~
../drivers/net/cxgbe/base/t4vf_hw.c: In function ‘t4vf_wr_mbox_core’:
../drivers/net/cxgbe/base/t4vf_hw.c:86:27: note: ‘entry’ declared here
   86 |         struct mbox_entry entry;
      |                           ^~~~~
../drivers/net/cxgbe/base/t4vf_hw.c:86:27: note: ‘adapter’ declared here

It is a valid compiler warning, make local variable a global one.

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>

---

Fix is done in a quickest way, mainly to report the issue,
please feel free to suggest another solution for the build error.
---
 drivers/net/cxgbe/base/t4vf_hw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/cxgbe/base/t4vf_hw.c b/drivers/net/cxgbe/base/t4vf_hw.c
index 561d759dbc0d..b42c4e78eba9 100644
--- a/drivers/net/cxgbe/base/t4vf_hw.c
+++ b/drivers/net/cxgbe/base/t4vf_hw.c
@@ -83,7 +83,7 @@ int t4vf_wr_mbox_core(struct adapter *adapter,
 
 	u32 mbox_ctl = T4VF_CIM_BASE_ADDR + A_CIM_VF_EXT_MAILBOX_CTRL;
 	__be64 cmd_rpl[MBOX_LEN / 8];
-	struct mbox_entry entry;
+	static struct mbox_entry entry;
 	unsigned int delay_idx;
 	u32 v, mbox_data;
 	const __be64 *p;
-- 
2.34.1