[RFC 4/6] net/axgbe: fix mutexes for multi-process

[Stephen Hemminger <stephen@networkplumber.org>]

The AXGBE driver supports secondary processes, as shown by the
explicit check in eth_axgbe_dev_init(). The xpcs_mutex, i2c_mutex,
an_mutex, and phy_mutex in axgbe_port are located in dev_private
which is in shared memory accessible by both primary and secondary
processes.

However, the mutexes are initialized without PTHREAD_PROCESS_SHARED
attribute, which means synchronization between processes is
undefined behavior.

POSIX mutexes are by default private to the process creating them.
When a mutex protects data structures in shared memory that are
accessed by multiple processes, pthread_mutexattr_setpshared() must
be called with PTHREAD_PROCESS_SHARED.

Bugzilla ID: 662
Fixes: 572890ef6625 ("net/axgbe: add structs for MAC init and reset")
Cc: stable@dpdk.org

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/net/axgbe/axgbe_ethdev.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/net/axgbe/axgbe_ethdev.c b/drivers/net/axgbe/axgbe_ethdev.c
index cf3b0d9ef5..0fedac72ab 100644
--- a/drivers/net/axgbe/axgbe_ethdev.c
+++ b/drivers/net/axgbe/axgbe_ethdev.c
@@ -193,6 +193,17 @@ static const struct axgbe_xstats axgbe_xstats_strings[] = {
 #define AMD_PCI_AXGBE_DEVICE_V2A 0x1458
 #define AMD_PCI_AXGBE_DEVICE_V2B 0x1459
 
+static void
+axgbe_init_mutex(pthread_mutex_t *mutex)
+{
+	pthread_mutexattr_t attr;
+
+	pthread_mutexattr_init(&attr);
+	pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
+	pthread_mutex_init(mutex, &attr);
+	pthread_mutexattr_destroy(&attr);
+}
+
 static const struct rte_pci_id pci_id_axgbe_map[] = {
 	{RTE_PCI_DEVICE(AMD_PCI_VENDOR_ID, AMD_PCI_AXGBE_DEVICE_V2A)},
 	{RTE_PCI_DEVICE(AMD_PCI_VENDOR_ID, AMD_PCI_AXGBE_DEVICE_V2B)},
@@ -2403,10 +2414,10 @@ eth_axgbe_dev_init(struct rte_eth_dev *eth_dev)
 
 	pdata->tx_desc_count = AXGBE_MAX_RING_DESC;
 	pdata->rx_desc_count = AXGBE_MAX_RING_DESC;
-	pthread_mutex_init(&pdata->xpcs_mutex, NULL);
-	pthread_mutex_init(&pdata->i2c_mutex, NULL);
-	pthread_mutex_init(&pdata->an_mutex, NULL);
-	pthread_mutex_init(&pdata->phy_mutex, NULL);
+	axgbe_init_mutex(&pdata->xpcs_mutex);
+	axgbe_init_mutex(&pdata->i2c_mutex);
+	axgbe_init_mutex(&pdata->an_mutex);
+	axgbe_init_mutex(&pdata->phy_mutex);
 
 	ret = pdata->phy_if.phy_init(pdata);
 	if (ret) {
-- 
2.51.0