-----Original Message----- >From: Stephen Hemminger [mailto:stephen at networkplumber.org] >Sent: Monday, April 06, 2015 11:05 AM >To: dev at dpdk.org >Subject: [dpdk-dev] [PATCH] eth_dev: make ether dev_ops const > >Ethernet device function tables should be immutable for correctness and >security. Special case for the test code driver. ... >diff --git a/app/test/virtual_pmd.c b/app/test/virtual_pmd.c index >f163562..f579558 100644 >--- a/app/test/virtual_pmd.c >+++ b/app/test/virtual_pmd.c ... >+/* This driver uses private mutable eth_dev_ops for each >+ * instance so it is safe to override const here. >+ */ >+#pragma GCC diagnostic push >+#pragma GCC diagnostic ignored "-Wcast-qual" > void > virtual_ethdev_start_fn_set_success(uint8_t port_id, uint8_t success) { > struct rte_eth_dev *vrtl_eth_dev = &rte_eth_devices[port_id]; >+ struct eth_dev_ops *dev_ops >+ = (struct eth_dev_ops *) vrtl_eth_dev->dev_ops; ...
If this is really safe, then you should be able to accomplish it without disabling a bunch of protection. I suggest adding a pointer that isn't const to the private data block and adjusting the allocated dispatch table through that instead of through the pointer to the immutable dispatch table you've established in struct rte_eth_dev. That reinforces the fact that modifying the dispatch table is a private matter within the driver while showing structurally exactly why it's safe to change it. And it's not nearly so ugly. -don provan dprovan at bivio.net
