From: Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>
To: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
Amit Prakash Shukla <amitprakashs@marvell.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"jerinj@marvell.com" <jerinj@marvell.com>,
"stable@dpdk.org" <stable@dpdk.org>, nd <nd@arm.com>
Subject: Re: [PATCH] ring: compilation fix with GCC-12
Date: Sun, 7 Aug 2022 13:26:09 +0100 [thread overview]
Message-ID: <2dee8dd1-dde5-6ef1-14d7-083c1bd9ab54@yandex.ru> (raw)
In-Reply-To: <DBAPR08MB58149CFBE86F8C3BA74D6F6B98619@DBAPR08MB5814.eurprd08.prod.outlook.com>
06/08/2022 19:35, Honnappa Nagarahalli пишет:
> <snip>
>
>>
>> GCC 12 raises the following warning:
>>
>> In function '__rte_ring_dequeue_elems_128',
>> inlined from '__rte_ring_dequeue_elems' at
>> ../lib/ring/rte_ring_elem_pvt.h:262:3,
>> inlined from '__rte_ring_do_hts_dequeue_elem' at
>> ../lib/ring/rte_ring_hts_elem_pvt.h:237:3,
>> inlined from 'rte_ring_mc_hts_dequeue_bulk_elem' at
>> ../lib/ring/rte_ring_hts.h:83:9,
>> inlined from 'rte_ring_dequeue_bulk_elem' at
>> ../lib/ring/rte_ring_elem.h:391:10,
>> inlined from 'rte_ring_dequeue_elem' at
>> ../lib/ring/rte_ring_elem.h:476:9,
>> inlined from 'rte_ring_dequeue' at
>> ../lib/ring/rte_ring.h:463:9,
>> inlined from 'rxa_intr_ring_dequeue' at
>> ../lib/eventdev/rte_event_eth_rx_adapter.c:1196:10:
>> ../lib/ring/rte_ring_elem_pvt.h:234:25: error: 'memcpy' writing
>> 32 bytes into a region of size 8 overflows the destination
>> [-Werror=stringop-overflow=]
>> 234 | memcpy((void *)(obj + i), (void *)(ring + idx), 32);
>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Replacing memcpy with rte_memcpy fixes the GCC-12 compilation issue.
> Any reason why this replacement fixes the problem?
> Do you have any performance numbers with this change?
>
>> Also it would be better to change to rte_memcpy as the function is called in
>> fastpath.
> On Arm platforms, memcpy in the later versions has the best performance.
I agree with Honnappa, it is better to keep memcpy() here.
Actually what is strange - why it ends up in
__rte_ring_dequeue_elems_128() at all?
Inside rxa_intr_ring_dequeue() we clearly doing: rte_ring_dequeue(),
which should boil down to ___rte_ring_dequeue_elems_64().
it should go to __rte_ring_dequeue_elems_128() at all.
Another q - is this warning happens only on arm platforms?
>
>>
>> Bugzilla ID: 1062
>> Fixes: 1fc73390bcf5 ("ring: refactor exported headers")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Amit Prakash Shukla <amitprakashs@marvell.com>
>> ---
>> lib/ring/rte_ring_elem_pvt.h | 18 ++++++++++--------
>> 1 file changed, 10 insertions(+), 8 deletions(-)
>>
>> diff --git a/lib/ring/rte_ring_elem_pvt.h b/lib/ring/rte_ring_elem_pvt.h index
>> 83788c56e6..3d85b13333 100644
>> --- a/lib/ring/rte_ring_elem_pvt.h
>> +++ b/lib/ring/rte_ring_elem_pvt.h
>> @@ -10,6 +10,8 @@
>> #ifndef _RTE_RING_ELEM_PVT_H_
>> #define _RTE_RING_ELEM_PVT_H_
>>
>> +#include <rte_memcpy.h>
>> +
>> static __rte_always_inline void
>> __rte_ring_enqueue_elems_32(struct rte_ring *r, const uint32_t size,
>> uint32_t idx, const void *obj_table, uint32_t n) @@ -97,20
>> +99,20 @@ __rte_ring_enqueue_elems_128(struct rte_ring *r, uint32_t
>> prod_head,
>> const rte_int128_t *obj = (const rte_int128_t *)obj_table;
>> if (likely(idx + n <= size)) {
>> for (i = 0; i < (n & ~0x1); i += 2, idx += 2)
>> - memcpy((void *)(ring + idx),
>> + rte_memcpy((void *)(ring + idx),
>> (const void *)(obj + i), 32);
>> switch (n & 0x1) {
>> case 1:
>> - memcpy((void *)(ring + idx),
>> + rte_memcpy((void *)(ring + idx),
>> (const void *)(obj + i), 16);
>> }
>> } else {
>> for (i = 0; idx < size; i++, idx++)
>> - memcpy((void *)(ring + idx),
>> + rte_memcpy((void *)(ring + idx),
>> (const void *)(obj + i), 16);
>> /* Start at the beginning */
>> for (idx = 0; i < n; i++, idx++)
>> - memcpy((void *)(ring + idx),
>> + rte_memcpy((void *)(ring + idx),
>> (const void *)(obj + i), 16);
>> }
>> }
>> @@ -231,17 +233,17 @@ __rte_ring_dequeue_elems_128(struct rte_ring *r,
>> uint32_t prod_head,
>> rte_int128_t *obj = (rte_int128_t *)obj_table;
>> if (likely(idx + n <= size)) {
>> for (i = 0; i < (n & ~0x1); i += 2, idx += 2)
>> - memcpy((void *)(obj + i), (void *)(ring + idx), 32);
>> + rte_memcpy((void *)(obj + i), (void *)(ring + idx), 32);
>> switch (n & 0x1) {
>> case 1:
>> - memcpy((void *)(obj + i), (void *)(ring + idx), 16);
>> + rte_memcpy((void *)(obj + i), (void *)(ring + idx), 16);
>> }
>> } else {
>> for (i = 0; idx < size; i++, idx++)
>> - memcpy((void *)(obj + i), (void *)(ring + idx), 16);
>> + rte_memcpy((void *)(obj + i), (void *)(ring + idx), 16);
>> /* Start at the beginning */
>> for (idx = 0; i < n; i++, idx++)
>> - memcpy((void *)(obj + i), (void *)(ring + idx), 16);
>> + rte_memcpy((void *)(obj + i), (void *)(ring + idx), 16);
>> }
>> }
>>
>> --
>> 2.25.1
>
next prev parent reply other threads:[~2022-08-07 12:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-05 9:03 Amit Prakash Shukla
2022-08-05 15:37 ` Stephen Hemminger
2022-08-06 18:35 ` Honnappa Nagarahalli
2022-08-07 12:26 ` Konstantin Ananyev [this message]
2022-08-23 9:38 ` [EXT] " Amit Prakash Shukla
2022-08-23 9:41 ` Amit Prakash Shukla
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