[PATCH v5 2/4] eal/linux: increase uevent socket buffer

The kernel netlink socket into DPDK can get overrun if DPDK
interrupt thread is not keeping up. To reduce the possibility
increase the socket receive buffer to 4M.

Fixes: 0d0f478d0483 ("eal/linux: add uevent parse and process")
Cc: [email protected]

Reported-by: Randy Tice <[email protected]>
Signed-off-by: Stephen Hemminger <[email protected]>
---
 lib/eal/linux/eal_dev.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/lib/eal/linux/eal_dev.c b/lib/eal/linux/eal_dev.c
index 666967667f..fb5c8bf070 100644
--- a/lib/eal/linux/eal_dev.c
+++ b/lib/eal/linux/eal_dev.c
@@ -32,6 +32,9 @@ static bool hotplug_handle;
 /* Listen only to messages from kernel (not libudev) */
 #define EAL_UEV_GROUP_KERNEL 1
 
+/* Large uevent buffer */
+#define EAL_UEV_MSG_RCVBUF (4 * 1024 * 1024)
+
 /*
  * spinlock for device hot-unplug failure handling. If it try to access bus or
  * device, such as handle sigbus on bus or handle memory failure for device
@@ -103,6 +106,29 @@ static int cmp_dev_name(const struct rte_device *dev,
 	return strcmp(dev->name, name);
 }
 
+/*
+ * To avoid losing uevents increase the netlink receive buffer size,
+ * and override the kernel clamp value if necessary.
+ */
+static int
+dev_uev_set_rcvbuf(int fd, int n)
+{
+	int ret, val;
+	socklen_t len = sizeof(val);
+
+	ret = setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &n, sizeof(n));
+	if (ret < 0)
+		return ret;
+
+	/* kernel may have clamped our request */
+	ret = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &val, &len);
+	if (ret >= 0 && len == sizeof(val) && val == n * 2)
+		return 0; /* request worked */
+
+	/* try again to override kernel restriction */
+	return setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &n, sizeof(n));
+}
+
 static int
 dev_uev_socket_fd_create(void)
 {
@@ -127,6 +153,9 @@ dev_uev_socket_fd_create(void)
 		goto err;
 	}
 
+	if (dev_uev_set_rcvbuf(fd, EAL_UEV_MSG_RCVBUF) < 0)
+		EAL_LOG(NOTICE, "Failed to set rcvbuf.");
+
 	if (rte_intr_fd_set(intr_handle, fd))
 		goto err;
 
-- 
2.53.0