[PATCH v3] lib/ring: do not allow zero size ring

[Isaac Boukris]

this might happen when for instance the ring size is read from
config, and would cause runtime crash. Do so by using the
RTE_IS_POWER_OF_2 macro.

Signed-off-by: Isaac Boukris <iboukris at gmail.com>
Acked-by: Wathsala Vithanage <wathsala.vithanage at arm.com>
Acked-by: Morten Brørup <mb at smartsharesystems.com>
---

v3:
* changed to use the RTE_IS_POWER_OF_2 macro.

v2:
* move the fix to the POWEROF2 macro itself.
* fixed style in the test code.

 app/test/test_ring.c | 7 +++++++
 lib/ring/rte_ring.c  | 8 +++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/app/test/test_ring.c b/app/test/test_ring.c
index ba1fec1de3..3078348b2f 100644
--- a/app/test/test_ring.c
+++ b/app/test/test_ring.c
@@ -505,6 +505,13 @@ test_ring_negative_tests(void)
 	struct rte_ring *rt = NULL;
 	unsigned int i;
 
+	/* Test zero size ring */
+	rp = test_ring_create("test_zero_size_ring", -1, 0, SOCKET_ID_ANY, 0);
+	if (rp != NULL) {
+		printf("Test failed to detect zero size ring\n");
+		goto test_fail;
+	}
+
 	/* Test with esize not a multiple of 4 */
 	rp = test_ring_create("test_bad_element_size", 23,
 				RING_SIZE + 1, SOCKET_ID_ANY, 0);
diff --git a/lib/ring/rte_ring.c b/lib/ring/rte_ring.c
index edd63aa535..f10050a1c4 100644
--- a/lib/ring/rte_ring.c
+++ b/lib/ring/rte_ring.c
@@ -25,6 +25,7 @@
 #include <rte_string_fns.h>
 #include <rte_tailq.h>
 #include <rte_telemetry.h>
+#include <rte_bitops.h>
 
 #include "rte_ring.h"
 #include "rte_ring_elem.h"
@@ -46,9 +47,6 @@ EAL_REGISTER_TAILQ(rte_ring_tailq)
 		     RING_F_MP_RTS_ENQ | RING_F_MC_RTS_DEQ |	       \
 		     RING_F_MP_HTS_ENQ | RING_F_MC_HTS_DEQ)
 
-/* true if x is a power of 2 */
-#define POWEROF2(x) ((((x)-1) & (x)) == 0)
-
 /* by default set head/tail distance as 1/8 of ring capacity */
 #define HTD_MAX_DEF	8
 
@@ -67,7 +65,7 @@ rte_ring_get_memsize_elem(unsigned int esize, unsigned int count)
 	}
 
 	/* count must be a power of 2 */
-	if ((!POWEROF2(count)) || (count > RTE_RING_SZ_MASK )) {
+	if ((!RTE_IS_POWER_OF_2(count)) || (count > RTE_RING_SZ_MASK)) {
 		RING_LOG(ERR,
 			"Requested number of elements is invalid, must be power of 2, and not exceed %u",
 			RTE_RING_SZ_MASK);
@@ -227,7 +225,7 @@ rte_ring_init(struct rte_ring *r, const char *name, unsigned int count,
 		r->mask = r->size - 1;
 		r->capacity = count;
 	} else {
-		if ((!POWEROF2(count)) || (count > RTE_RING_SZ_MASK)) {
+		if ((!RTE_IS_POWER_OF_2(count)) || (count > RTE_RING_SZ_MASK)) {
 			RING_LOG(ERR,
 				"Requested size is invalid, must be power of 2, and not exceed the size limit %u",
 				RTE_RING_SZ_MASK);
-- 
2.49.0