On 10/05/2021 16:03, Ferruh Yigit wrote:
> Reproduced with '--buildtype=debugoptimized' config,
> compiler version: gcc (GCC) 12.0.0 20210509 (experimental)
>
> There are multiple build errors, like:
> In file included from ../drivers/net/tap/tap_flow.c:13:
> In function ‘rte_jhash_2hashes’,
> inlined from ‘rte_jhash’ at ../lib/hash/rte_jhash.h:284:2,
> inlined from ‘tap_flow_set_handle’ at
> ../drivers/net/tap/tap_flow.c:1306:12,
> inlined from ‘rss_enable’ at ../drivers/net/tap/tap_flow.c:1909:3,
> inlined from ‘priv_flow_process’ at
> ../drivers/net/tap/tap_flow.c:1228:11:
> ../lib/hash/rte_jhash.h:238:9:
> warning: ‘flow’ may be used uninitialized [-Wmaybe-uninitialized]
> 238 | __rte_jhash_2hashes(key, length, pc, pb, 1);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/net/tap/tap_flow.c: In function ‘priv_flow_process’:
> ../lib/hash/rte_jhash.h:81:1: note: by argument 1 of type ‘const void *’
> to ‘__rte_jhash_2hashes.constprop’ declared here
> 81 | __rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc,
> | ^~~~~~~~~~~~~~~~~~~
> ../drivers/net/tap/tap_flow.c:1028:1: note: ‘flow’ declared here
> 1028 | priv_flow_process(struct pmd_internals *pmd,
> | ^~~~~~~~~~~~~~~~~
>
> Fix strict aliasing rule by using union.
>
Bugzilla ID: 690
> Fixes: de96fe68ae95 ("net/tap: add basic flow API patterns and actions")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Ferruh Yigit <ferruh.yi...@intel.com>
Acked-by: Kevin Traynor <ktray...@redhat.com>
> ---
> Cc: pascal.ma...@6wind.com
> ---
> drivers/net/tap/tap_flow.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
> index 1ee6fb30ab2d..c4f60ce98e5e 100644
> --- a/drivers/net/tap/tap_flow.c
> +++ b/drivers/net/tap/tap_flow.c
> @@ -1300,10 +1300,16 @@ tap_flow_validate(struct rte_eth_dev *dev,
> static void
> tap_flow_set_handle(struct rte_flow *flow)
> {
> + union {
> + struct rte_flow *flow;
> + const void *key;
> + } tmp;
> uint32_t handle = 0;
>
> + tmp.flow = flow;
> +
> if (sizeof(flow) > 4)
> - handle = rte_jhash(&flow, sizeof(flow), 1);
> + handle = rte_jhash(tmp.key, sizeof(flow), 1);
> else
> handle = (uintptr_t)flow;
> /* must be at least 1 to avoid letting the kernel choose one for us */
>
