[PATCH v2 1/2] net/i40e: fix return value of close operation

[Sid Ali Cherrati <scherrati1@gmail.com>]

rte_intr_callback_unregister() returns the number of unregistered
callbacks on success. Since the close operation started returning
the ret variable instead of 0, this positive value leaks as the
return value of i40e_dev_close(), so applications checking
rte_eth_dev_close() != 0 treat a successful close as a failure.

Use a separate cb_ret variable for the unregister return value so a
successful unregister never clobbers an earlier error stored in ret,
and stop retrying once unregister fails with anything other than
-EAGAIN, since those errors are not transient.

Fixes: 62024eb82756 ("ethdev: change stop operation callback to return int")
Cc: stable@dpdk.org

Signed-off-by: Sid Ali Cherrati <scherrati1@gmail.com>
---
v2: use a temporary cb_ret variable instead of unconditionally zeroing
    ret, and stop retrying on a non-transient unregister error, so an
    earlier error is not lost or masked by a successful/failed
    unregister

 drivers/net/intel/i40e/i40e_ethdev.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/intel/i40e/i40e_ethdev.c b/drivers/net/intel/i40e/i40e_ethdev.c
index b6b2d291ee..b5457bcf2e 100644
--- a/drivers/net/intel/i40e/i40e_ethdev.c
+++ b/drivers/net/intel/i40e/i40e_ethdev.c
@@ -2693,6 +2693,7 @@ i40e_dev_close(struct rte_eth_dev *dev)
 	uint32_t reg;
 	int i;
 	int ret;
+	int cb_ret;
 	uint8_t aq_fail = 0;
 	int retries = 0;
 
@@ -2761,14 +2762,17 @@ i40e_dev_close(struct rte_eth_dev *dev)
 	i40e_pf_host_uninit(dev);
 
 	do {
-		ret = rte_intr_callback_unregister(intr_handle,
+		cb_ret = rte_intr_callback_unregister(intr_handle,
 				i40e_dev_interrupt_handler, dev);
-		if (ret >= 0 || ret == -ENOENT) {
+		if (cb_ret >= 0 || cb_ret == -ENOENT) {
 			break;
-		} else if (ret != -EAGAIN) {
+		} else if (cb_ret != -EAGAIN) {
 			PMD_INIT_LOG(ERR,
 				 "intr callback unregister failed: %d",
-				 ret);
+				 cb_ret);
+			if (ret == 0)
+				ret = cb_ret;
+			break;
 		}
 		i40e_msec_delay(500);
 	} while (retries++ < 5);
-- 
2.34.1