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authorBenoît Ganne <bganne@cisco.com>2021-04-29 18:24:24 +0200
committerDamjan Marion <dmarion@me.com>2021-05-21 19:50:14 +0000
commita42c41be4eed3e1ce2a42038b07ce1d3420891cd (patch)
treefc95c7c24cbef993cc2bef8742b3360123d70b66 /src/plugins/af_xdp/input.c
parent92a8d761c412590f5112239be4c511091b2b2d5a (diff)
af_xdp: workaround kernel race between poll() and sendmsg()
Prior to Linux 5.6 there is a race condition between poll() and sendmsg() in the kernel. This patch protects the syscalls with a lock to prevent it, unless the NO_SYSCALL_LOCK flag is set at create time. See https://lore.kernel.org/bpf/BYAPR11MB365382C5DB1E5FCC53242609C1549@BYAPR11MB3653.namprd11.prod.outlook.com/ Type: fix Change-Id: Ie7d4f5cb41f697b11a09b6046e54d190430d76df Signed-off-by: Benoît Ganne <bganne@cisco.com>
Diffstat (limited to 'src/plugins/af_xdp/input.c')
-rw-r--r--src/plugins/af_xdp/input.c35
1 files changed, 19 insertions, 16 deletions
diff --git a/src/plugins/af_xdp/input.c b/src/plugins/af_xdp/input.c
index da422bdccaf..dcbf5a4b587 100644
--- a/src/plugins/af_xdp/input.c
+++ b/src/plugins/af_xdp/input.c
@@ -24,9 +24,9 @@
#include <vnet/interface/rx_queue_funcs.h>
#include "af_xdp.h"
-#define foreach_af_xdp_input_error \
- _(POLL_REQUIRED, "poll required") \
- _(POLL_FAILURES, "poll failures")
+#define foreach_af_xdp_input_error \
+ _ (SYSCALL_REQUIRED, "syscall required") \
+ _ (SYSCALL_FAILURES, "syscall failures")
typedef enum
{
@@ -77,25 +77,28 @@ af_xdp_device_input_refill_db (vlib_main_t * vm,
af_xdp_device_t * ad, af_xdp_rxq_t * rxq,
const u32 n_alloc)
{
- int ret;
-
xsk_ring_prod__submit (&rxq->fq, n_alloc);
- if (!xsk_ring_prod__needs_wakeup (&rxq->fq))
+ if (AF_XDP_RXQ_MODE_INTERRUPT == rxq->mode ||
+ !xsk_ring_prod__needs_wakeup (&rxq->fq))
return;
- vlib_error_count (vm, node->node_index, AF_XDP_INPUT_ERROR_POLL_REQUIRED,
+ vlib_error_count (vm, node->node_index, AF_XDP_INPUT_ERROR_SYSCALL_REQUIRED,
1);
- struct pollfd fd = {.fd = rxq->xsk_fd,.events = POLLIN };
- ret = poll (&fd, 1, 0);
- if (PREDICT_TRUE (ret >= 0))
- return;
-
- /* something bad is happening */
- vlib_error_count (vm, node->node_index, AF_XDP_INPUT_ERROR_POLL_FAILURES,
- 1);
- af_xdp_device_error (ad, "poll() failed");
+ if (clib_spinlock_trylock_if_init (&rxq->syscall_lock))
+ {
+ struct pollfd fd = { .fd = rxq->xsk_fd, .events = POLLIN | POLLOUT };
+ int ret = poll (&fd, 1, 0);
+ clib_spinlock_unlock_if_init (&rxq->syscall_lock);
+ if (PREDICT_FALSE (ret < 0))
+ {
+ /* something bad is happening */
+ vlib_error_count (vm, node->node_index,
+ AF_XDP_INPUT_ERROR_SYSCALL_FAILURES, 1);
+ af_xdp_device_error (ad, "rx poll() failed");
+ }
+ }
}
static_always_inline void