As described in the previous commit, napi_synchronize doesn't quite fit
the purpose when we just need to wait until the currently running NAPI
quits. Its implementation waits until NAPI is not running by polling and
waiting for 1ms in between. In cases where we need to deactivate one
queue (e.g., recovery flows) or where we deactivate them one-by-one
(deactivate channel flow), we may get stuck in napi_synchronize forever
if other queues keep NAPI active, causing a soft lockup. Depending on
kernel configuration (CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC), it may result
in a kernel panic.
To fix the issue, use synchronize_rcu to wait for NAPI to quit, and wrap
the whole NAPI in rcu_read_lock.
Fixes:
acc6c5953af1 ("net/mlx5e: Split open/close channels to stages")
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
{
struct xdp_buff *xdp = wi->umr.dma_info[page_idx].xsk;
u32 cqe_bcnt32 = cqe_bcnt;
- bool consumed;
/* Check packet size. Note LRO doesn't use linear SKB */
if (unlikely(cqe_bcnt > rq->hw_mtu)) {
xsk_buff_dma_sync_for_cpu(xdp);
prefetch(xdp->data);
- rcu_read_lock();
- consumed = mlx5e_xdp_handle(rq, NULL, &cqe_bcnt32, xdp);
- rcu_read_unlock();
-
/* Possible flows:
* - XDP_REDIRECT to XSKMAP:
* The page is owned by the userspace from now.
* allocated first from the Reuse Ring, so it has enough space.
*/
- if (likely(consumed)) {
+ if (likely(mlx5e_xdp_handle(rq, NULL, &cqe_bcnt32, xdp))) {
if (likely(__test_and_clear_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags)))
__set_bit(page_idx, wi->xdp_xmit_bitmap); /* non-atomic */
return NULL; /* page/packet was consumed by XDP */
u32 cqe_bcnt)
{
struct xdp_buff *xdp = wi->di->xsk;
- bool consumed;
/* wi->offset is not used in this function, because xdp->data and the
* DMA address point directly to the necessary place. Furthermore, the
return NULL;
}
- rcu_read_lock();
- consumed = mlx5e_xdp_handle(rq, NULL, &cqe_bcnt, xdp);
- rcu_read_unlock();
-
- if (likely(consumed))
+ if (likely(mlx5e_xdp_handle(rq, NULL, &cqe_bcnt, xdp)))
return NULL; /* page/packet was consumed by XDP */
/* XDP_PASS: copy the data from the UMEM to a new SKB. The frame reuse
void mlx5e_close_xsk(struct mlx5e_channel *c)
{
clear_bit(MLX5E_CHANNEL_STATE_XSK, c->state);
- napi_synchronize(&c->napi);
- synchronize_rcu(); /* Sync with the XSK wakeup. */
+ synchronize_rcu(); /* Sync with the XSK wakeup and with NAPI. */
mlx5e_close_rq(&c->xskrq);
mlx5e_close_cq(&c->xskrq.cq);
void mlx5e_deactivate_rq(struct mlx5e_rq *rq)
{
clear_bit(MLX5E_RQ_STATE_ENABLED, &rq->state);
- napi_synchronize(&rq->channel->napi); /* prevent mlx5e_post_rx_wqes */
+ synchronize_rcu(); /* Sync with NAPI to prevent mlx5e_post_rx_wqes. */
}
void mlx5e_close_rq(struct mlx5e_rq *rq)
static void mlx5e_deactivate_txqsq(struct mlx5e_txqsq *sq)
{
- struct mlx5e_channel *c = sq->channel;
struct mlx5_wq_cyc *wq = &sq->wq;
clear_bit(MLX5E_SQ_STATE_ENABLED, &sq->state);
- /* prevent netif_tx_wake_queue */
- napi_synchronize(&c->napi);
+ synchronize_rcu(); /* Sync with NAPI to prevent netif_tx_wake_queue. */
mlx5e_tx_disable_queue(sq->txq);
void mlx5e_deactivate_icosq(struct mlx5e_icosq *icosq)
{
- struct mlx5e_channel *c = icosq->channel;
-
clear_bit(MLX5E_SQ_STATE_ENABLED, &icosq->state);
- napi_synchronize(&c->napi);
+ synchronize_rcu(); /* Sync with NAPI. */
}
void mlx5e_close_icosq(struct mlx5e_icosq *sq)
struct mlx5e_channel *c = sq->channel;
clear_bit(MLX5E_SQ_STATE_ENABLED, &sq->state);
- napi_synchronize(&c->napi);
+ synchronize_rcu(); /* Sync with NAPI. */
mlx5e_destroy_sq(c->mdev, sq->sqn);
mlx5e_free_xdpsq_descs(sq);
struct xdp_buff xdp;
struct sk_buff *skb;
void *va, *data;
- bool consumed;
u32 frag_size;
va = page_address(di->page) + wi->offset;
prefetchw(va); /* xdp_frame data area */
prefetch(data);
- rcu_read_lock();
mlx5e_fill_xdp_buff(rq, va, rx_headroom, cqe_bcnt, &xdp);
- consumed = mlx5e_xdp_handle(rq, di, &cqe_bcnt, &xdp);
- rcu_read_unlock();
- if (consumed)
+ if (mlx5e_xdp_handle(rq, di, &cqe_bcnt, &xdp))
return NULL; /* page/packet was consumed by XDP */
rx_headroom = xdp.data - xdp.data_hard_start;
struct sk_buff *skb;
void *va, *data;
u32 frag_size;
- bool consumed;
/* Check packet size. Note LRO doesn't use linear SKB */
if (unlikely(cqe_bcnt > rq->hw_mtu)) {
prefetchw(va); /* xdp_frame data area */
prefetch(data);
- rcu_read_lock();
mlx5e_fill_xdp_buff(rq, va, rx_headroom, cqe_bcnt32, &xdp);
- consumed = mlx5e_xdp_handle(rq, di, &cqe_bcnt32, &xdp);
- rcu_read_unlock();
- if (consumed) {
+ if (mlx5e_xdp_handle(rq, di, &cqe_bcnt32, &xdp)) {
if (__test_and_clear_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags))
__set_bit(page_idx, wi->xdp_xmit_bitmap); /* non-atomic */
return NULL; /* page/packet was consumed by XDP */
struct mlx5e_xdpsq *xsksq = &c->xsksq;
struct mlx5e_rq *xskrq = &c->xskrq;
struct mlx5e_rq *rq = &c->rq;
- bool xsk_open = test_bit(MLX5E_CHANNEL_STATE_XSK, c->state);
bool aff_change = false;
bool busy_xsk = false;
bool busy = false;
int work_done = 0;
+ bool xsk_open;
int i;
+ rcu_read_lock();
+
+ xsk_open = test_bit(MLX5E_CHANNEL_STATE_XSK, c->state);
+
ch_stats->poll++;
for (i = 0; i < c->num_tc; i++)
busy |= busy_xsk;
if (busy) {
- if (likely(mlx5e_channel_no_affinity_change(c)))
- return budget;
+ if (likely(mlx5e_channel_no_affinity_change(c))) {
+ work_done = budget;
+ goto out;
+ }
ch_stats->aff_change++;
aff_change = true;
if (budget && work_done == budget)
}
if (unlikely(!napi_complete_done(napi, work_done)))
- return work_done;
+ goto out;
ch_stats->arm++;
ch_stats->force_irq++;
}
+out:
+ rcu_read_unlock();
+
return work_done;
}
OSDN Git Service
