There are two lines that were using VLAs, which are not supported by
MSVC.
1)
../lib/rcu/rte_rcu_qsbr.c:326:12: warning: variable length array used [-Wvla]
326 | char data[dq->esize];
| ^~~~~~~~~
2)
../lib/rcu/rte_rcu_qsbr.c:389:12: warning: variable length array used [-Wvla]
389 | char data[dq->esize];
| ^~~~~~~~~
The short-term fix is to use alloca, to allow progress with the msvc
compatibility work.
The long-term plan involves API changes and therefore can only be applied
with a new release. This long-term plan consists of introducing some
reasonable limitation on RCU DQ element size.
Signed-off-by: Andre Muezerie <andre...@linux.microsoft.com>
---
lib/rcu/meson.build | 7 -------
lib/rcu/rte_rcu_qsbr.c | 6 +++---
2 files changed, 3 insertions(+), 10 deletions(-)
diff --git a/lib/rcu/meson.build b/lib/rcu/meson.build
index fb1f49ba63..71143f5210 100644
--- a/lib/rcu/meson.build
+++ b/lib/rcu/meson.build
@@ -11,10 +11,3 @@ sources = files('rte_rcu_qsbr.c')
headers = files('rte_rcu_qsbr.h')
deps += ['ring']
-
-# FIXME: this library was enabled for mingw target (a Windows target).
-# Relying on no_wvla_cflag would trigger a build error until the VLA in
rte_rcu_qsbr.c is removed.
-# Disable the warning here for now.
-if cc.has_argument('-Wvla')
- cflags += '-Wno-vla'
-endif
diff --git a/lib/rcu/rte_rcu_qsbr.c b/lib/rcu/rte_rcu_qsbr.c
index dbf31501a6..3f619e1607 100644
--- a/lib/rcu/rte_rcu_qsbr.c
+++ b/lib/rcu/rte_rcu_qsbr.c
@@ -323,7 +323,7 @@ int rte_rcu_qsbr_dq_enqueue(struct rte_rcu_qsbr_dq *dq,
void *e)
return 1;
}
- char data[dq->esize];
+ char *data = alloca(dq->esize);
dq_elem = (__rte_rcu_qsbr_dq_elem_t *)data;
/* Start the grace period */
dq_elem->token = rte_rcu_qsbr_start(dq->v);
@@ -386,10 +386,10 @@ rte_rcu_qsbr_dq_reclaim(struct rte_rcu_qsbr_dq *dq,
unsigned int n,
cnt = 0;
- char data[dq->esize];
+ char *data = alloca(dq->esize);
/* Check reader threads quiescent state and reclaim resources */
while (cnt < n &&
- rte_ring_dequeue_bulk_elem_start(dq->r, &data,
+ rte_ring_dequeue_bulk_elem_start(dq->r, data,
dq->esize, 1, available) != 0) {
dq_elem = (__rte_rcu_qsbr_dq_elem_t *)data;
--
2.48.1.vfs.0.0
