Re: [dpdk-dev] [PATCH 1/2] test/rcu: fix array subscript is above array bounds

[Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>]

Hi Honnappa,

I verified building and testing and all the warnings/errors disappear 
for RTE_MAX_LCORE >= 2 and tests pass.

I wonder, if it is possible to set RTE_MAX_LCORE = 1 ?
In such case there are still few places with array bounds exceedings:
Compiling C object 'app/test/3062f5d@@dpdk-test@exe/test_rcu_qsbr.c.o'.
../app/test/test_rcu_qsbr.c: In function ‘test_rcu_qsbr_check_reader’:
../app/test/test_rcu_qsbr.c:319:24: warning: array subscript is above 
array bounds [-Warray-bounds]
         enabled_core_ids[i]);
         ~~~~~~~~~~~~~~~~^~~
../app/test/test_rcu_qsbr.c: In function ‘test_rcu_qsbr_main’:
../app/test/test_rcu_qsbr.c:946:2: warning: array subscript is above 
array bounds [-Warray-bounds]
   rte_rcu_qsbr_init(t[1], RTE_MAX_LCORE);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../app/test/test_rcu_qsbr.c:954:3: warning: array subscript is above 
array bounds [-Warray-bounds]
    rte_rcu_qsbr_thread_register(t[1], enabled_core_ids[i]);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../app/test/test_rcu_qsbr.c:957:2: warning: array subscript is above 
array bounds [-Warray-bounds]
   rte_rcu_qsbr_dump(stdout, t[1]);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../app/test/test_rcu_qsbr.c:486:53: warning: array subscript is above 
array bounds [-Warray-bounds]
   rte_rcu_qsbr_thread_register(t[0], enabled_core_ids[1]);
                                      ~~~~~~~~~~~~~~~~^~~
...and few more in other files.


Best regards

Lukasz

W dniu 16.10.2020 o 08:03, Honnappa Nagarahalli pisze:
> When RTE_MAX_LCORE value is small, following compiler errors
> are observed.
>
> ../app/test/test_rcu_qsbr.c:296:54: error: iteration 2 invokes
> undefined behavior [-Werror=aggressive-loop-optimizations]
>
> ../app/test/test_rcu_qsbr.c:315:55: error: array subscript is above
> array bounds [-Werror=array-bounds]
>
> Fixes: b87089b0bb19 ("test/rcu: add API and functional tests")
> Cc: stable@dpdk.org
>
> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> ---
>   app/test/test_rcu_qsbr.c | 56 +++++++++++++++++++++++-----------------
>   1 file changed, 33 insertions(+), 23 deletions(-)
>
> diff --git a/app/test/test_rcu_qsbr.c b/app/test/test_rcu_qsbr.c
> index 0a9e5ecd1..848a68092 100644
> --- a/app/test/test_rcu_qsbr.c
> +++ b/app/test/test_rcu_qsbr.c
> @@ -286,13 +286,13 @@ static int
>   test_rcu_qsbr_start(void)
>   {
>   	uint64_t token;
> -	int i;
> +	unsigned int i;
>   
>   	printf("\nTest rte_rcu_qsbr_start()\n");
>   
>   	rte_rcu_qsbr_init(t[0], RTE_MAX_LCORE);
>   
> -	for (i = 0; i < 3; i++)
> +	for (i = 0; i < num_cores; i++)
>   		rte_rcu_qsbr_thread_register(t[0], enabled_core_ids[i]);
>   
>   	token = rte_rcu_qsbr_start(t[0]);
> @@ -306,14 +306,18 @@ test_rcu_qsbr_check_reader(void *arg)
>   {
>   	struct rte_rcu_qsbr *temp;
>   	uint8_t read_type = (uint8_t)((uintptr_t)arg);
> +	unsigned int i;
>   
>   	temp = t[read_type];
>   
>   	/* Update quiescent state counter */
> -	rte_rcu_qsbr_quiescent(temp, enabled_core_ids[0]);
> -	rte_rcu_qsbr_quiescent(temp, enabled_core_ids[1]);
> -	rte_rcu_qsbr_thread_unregister(temp, enabled_core_ids[2]);
> -	rte_rcu_qsbr_quiescent(temp, enabled_core_ids[3]);
> +	for (i = 0; i < num_cores; i++) {
> +		if (i % 2 == 0)
> +			rte_rcu_qsbr_quiescent(temp, enabled_core_ids[i]);
> +		else
> +			rte_rcu_qsbr_thread_unregister(temp,
> +							enabled_core_ids[i]);
> +	}
>   	return 0;
>   }
>   
> @@ -324,7 +328,8 @@ test_rcu_qsbr_check_reader(void *arg)
>   static int
>   test_rcu_qsbr_check(void)
>   {
> -	int i, ret;
> +	int ret;
> +	unsigned int i;
>   	uint64_t token;
>   
>   	printf("\nTest rte_rcu_qsbr_check()\n");
> @@ -342,7 +347,7 @@ test_rcu_qsbr_check(void)
>   	ret = rte_rcu_qsbr_check(t[0], token, true);
>   	TEST_RCU_QSBR_RETURN_IF_ERROR((ret == 0), "Blocking QSBR check");
>   
> -	for (i = 0; i < 3; i++)
> +	for (i = 0; i < num_cores; i++)
>   		rte_rcu_qsbr_thread_register(t[0], enabled_core_ids[i]);
>   
>   	ret = rte_rcu_qsbr_check(t[0], token, false);
> @@ -357,7 +362,7 @@ test_rcu_qsbr_check(void)
>   	/* Threads are offline, hence this should pass */
>   	TEST_RCU_QSBR_RETURN_IF_ERROR((ret == 0), "Non-blocking QSBR check");
>   
> -	for (i = 0; i < 3; i++)
> +	for (i = 0; i < num_cores; i++)
>   		rte_rcu_qsbr_thread_unregister(t[0], enabled_core_ids[i]);
>   
>   	ret = rte_rcu_qsbr_check(t[0], token, true);
> @@ -365,7 +370,7 @@ test_rcu_qsbr_check(void)
>   
>   	rte_rcu_qsbr_init(t[0], RTE_MAX_LCORE);
>   
> -	for (i = 0; i < 4; i++)
> +	for (i = 0; i < num_cores; i++)
>   		rte_rcu_qsbr_thread_register(t[0], enabled_core_ids[i]);
>   
>   	token = rte_rcu_qsbr_start(t[0]);
> @@ -928,7 +933,7 @@ test_rcu_qsbr_dq_functional(int32_t size, int32_t esize, uint32_t flags)
>   static int
>   test_rcu_qsbr_dump(void)
>   {
> -	int i;
> +	unsigned int i;
>   
>   	printf("\nTest rte_rcu_qsbr_dump()\n");
>   
> @@ -945,7 +950,7 @@ test_rcu_qsbr_dump(void)
>   
>   	rte_rcu_qsbr_thread_register(t[0], enabled_core_ids[0]);
>   
> -	for (i = 1; i < 3; i++)
> +	for (i = 1; i < num_cores; i++)
>   		rte_rcu_qsbr_thread_register(t[1], enabled_core_ids[i]);
>   
>   	rte_rcu_qsbr_dump(stdout, t[0]);
> @@ -1095,7 +1100,7 @@ test_rcu_qsbr_sw_sv_3qs(void)
>   {
>   	uint64_t token[3];
>   	uint32_t c;
> -	int i;
> +	int i, num_readers;
>   	int32_t pos[3];
>   
>   	writer_done = 0;
> @@ -1118,7 +1123,11 @@ test_rcu_qsbr_sw_sv_3qs(void)
>   	thread_info[0].ih = 0;
>   
>   	/* Reader threads are launched */
> -	for (i = 0; i < 4; i++)
> +	/* Keep the number of reader threads low to reduce
> +	 * the execution time.
> +	 */
> +	num_readers = num_cores < 4 ? num_cores : 4;
> +	for (i = 0; i < num_readers; i++)
>   		rte_eal_remote_launch(test_rcu_qsbr_reader, &thread_info[0],
>   					enabled_core_ids[i]);
>   
> @@ -1151,7 +1160,7 @@ test_rcu_qsbr_sw_sv_3qs(void)
>   
>   	/* Check the quiescent state status */
>   	rte_rcu_qsbr_check(t[0], token[0], true);
> -	for (i = 0; i < 4; i++) {
> +	for (i = 0; i < num_readers; i++) {
>   		c = hash_data[0][0][enabled_core_ids[i]];
>   		if (c != COUNTER_VALUE && c != 0) {
>   			printf("Reader lcore %d did not complete #0 = %d\n",
> @@ -1169,7 +1178,7 @@ test_rcu_qsbr_sw_sv_3qs(void)
>   
>   	/* Check the quiescent state status */
>   	rte_rcu_qsbr_check(t[0], token[1], true);
> -	for (i = 0; i < 4; i++) {
> +	for (i = 0; i < num_readers; i++) {
>   		c = hash_data[0][3][enabled_core_ids[i]];
>   		if (c != COUNTER_VALUE && c != 0) {
>   			printf("Reader lcore %d did not complete #3 = %d\n",
> @@ -1187,7 +1196,7 @@ test_rcu_qsbr_sw_sv_3qs(void)
>   
>   	/* Check the quiescent state status */
>   	rte_rcu_qsbr_check(t[0], token[2], true);
> -	for (i = 0; i < 4; i++) {
> +	for (i = 0; i < num_readers; i++) {
>   		c = hash_data[0][6][enabled_core_ids[i]];
>   		if (c != COUNTER_VALUE && c != 0) {
>   			printf("Reader lcore %d did not complete #6 = %d\n",
> @@ -1206,7 +1215,7 @@ test_rcu_qsbr_sw_sv_3qs(void)
>   	writer_done = 1;
>   
>   	/* Wait and check return value from reader threads */
> -	for (i = 0; i < 4; i++)
> +	for (i = 0; i < num_readers; i++)
>   		if (rte_eal_wait_lcore(enabled_core_ids[i]) < 0)
>   			goto error;
>   	rte_hash_free(h[0]);
> @@ -1236,6 +1245,12 @@ test_rcu_qsbr_mw_mv_mqs(void)
>   	unsigned int i, j;
>   	unsigned int test_cores;
>   
> +	if (RTE_MAX_LCORE < 5 || num_cores < 4) {
> +		printf("Not enough cores for %s, expecting at least 5\n",
> +			__func__);
> +		return TEST_SKIPPED;
> +	}
> +
>   	writer_done = 0;
>   	test_cores = num_cores / 4;
>   	test_cores = test_cores * 4;
> @@ -1321,11 +1336,6 @@ test_rcu_qsbr_main(void)
>   {
>   	uint16_t core_id;
>   
> -	if (rte_lcore_count() < 5) {
> -		printf("Not enough cores for rcu_qsbr_autotest, expecting at least 5\n");
> -		return TEST_SKIPPED;
> -	}
> -
>   	num_cores = 0;
>   	RTE_LCORE_FOREACH_SLAVE(core_id) {
>   		enabled_core_ids[num_cores] = core_id;

-- 
Lukasz Wojciechowski
Principal Software Engineer

Samsung R&D Institute Poland
Samsung Electronics
Office +48 22 377 88 25
l.wojciechow@partner.samsung.com