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authorDaniel Borkmann <daniel@iogearbox.net>2018-08-09 21:50:45 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2018-08-09 21:50:45 +0200
commit9c95420117393ed5f76de373e3c6479c21e3e380 (patch)
treee758a1cbc47dcaff5e9c13ee2b336dd48994c881
parentbf9bae0ea6ec7013ef37b19fbbf29b62a35474fb (diff)
parent1bf9116d0866a649104a5dfa008c302ad54d1e02 (diff)
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Merge branch 'bpf-fix-cpu-and-devmap-teardown'
Jesper Dangaard Brouer says: ==================== Removing entries from cpumap and devmap, goes through a number of syncronization steps to make sure no new xdp_frames can be enqueued. But there is a small chance, that xdp_frames remains which have not been flushed/processed yet. Flushing these during teardown, happens from RCU context and not as usual under RX NAPI context. The optimization introduced in commt 389ab7f01af9 ("xdp: introduce xdp_return_frame_rx_napi"), missed that the flush operation can also be called from RCU context. Thus, we cannot always use the xdp_return_frame_rx_napi call, which take advantage of the protection provided by XDP RX running under NAPI protection. The samples/bpf xdp_redirect_cpu have a --stress-mode, that is adjusted to easier reproduce (verified by Red Hat QA). ==================== Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
-rw-r--r--kernel/bpf/cpumap.c15
-rw-r--r--kernel/bpf/devmap.c14
-rw-r--r--samples/bpf/xdp_redirect_cpu_kern.c2
-rw-r--r--samples/bpf/xdp_redirect_cpu_user.c4
4 files changed, 21 insertions, 14 deletions
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index e0918d180f08..46f5f29605d4 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -69,7 +69,7 @@ struct bpf_cpu_map {
};
static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
- struct xdp_bulk_queue *bq);
+ struct xdp_bulk_queue *bq, bool in_napi_ctx);
static u64 cpu_map_bitmap_size(const union bpf_attr *attr)
{
@@ -375,7 +375,7 @@ static void __cpu_map_entry_free(struct rcu_head *rcu)
struct xdp_bulk_queue *bq = per_cpu_ptr(rcpu->bulkq, cpu);
/* No concurrent bq_enqueue can run at this point */
- bq_flush_to_queue(rcpu, bq);
+ bq_flush_to_queue(rcpu, bq, false);
}
free_percpu(rcpu->bulkq);
/* Cannot kthread_stop() here, last put free rcpu resources */
@@ -558,7 +558,7 @@ const struct bpf_map_ops cpu_map_ops = {
};
static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
- struct xdp_bulk_queue *bq)
+ struct xdp_bulk_queue *bq, bool in_napi_ctx)
{
unsigned int processed = 0, drops = 0;
const int to_cpu = rcpu->cpu;
@@ -578,7 +578,10 @@ static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
err = __ptr_ring_produce(q, xdpf);
if (err) {
drops++;
- xdp_return_frame_rx_napi(xdpf);
+ if (likely(in_napi_ctx))
+ xdp_return_frame_rx_napi(xdpf);
+ else
+ xdp_return_frame(xdpf);
}
processed++;
}
@@ -598,7 +601,7 @@ static int bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf)
struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq);
if (unlikely(bq->count == CPU_MAP_BULK_SIZE))
- bq_flush_to_queue(rcpu, bq);
+ bq_flush_to_queue(rcpu, bq, true);
/* Notice, xdp_buff/page MUST be queued here, long enough for
* driver to code invoking us to finished, due to driver
@@ -661,7 +664,7 @@ void __cpu_map_flush(struct bpf_map *map)
/* Flush all frames in bulkq to real queue */
bq = this_cpu_ptr(rcpu->bulkq);
- bq_flush_to_queue(rcpu, bq);
+ bq_flush_to_queue(rcpu, bq, true);
/* If already running, costs spin_lock_irqsave + smb_mb */
wake_up_process(rcpu->kthread);
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index d361fc1e3bf3..750d45edae79 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -217,7 +217,8 @@ void __dev_map_insert_ctx(struct bpf_map *map, u32 bit)
}
static int bq_xmit_all(struct bpf_dtab_netdev *obj,
- struct xdp_bulk_queue *bq, u32 flags)
+ struct xdp_bulk_queue *bq, u32 flags,
+ bool in_napi_ctx)
{
struct net_device *dev = obj->dev;
int sent = 0, drops = 0, err = 0;
@@ -254,7 +255,10 @@ error:
struct xdp_frame *xdpf = bq->q[i];
/* RX path under NAPI protection, can return frames faster */
- xdp_return_frame_rx_napi(xdpf);
+ if (likely(in_napi_ctx))
+ xdp_return_frame_rx_napi(xdpf);
+ else
+ xdp_return_frame(xdpf);
drops++;
}
goto out;
@@ -286,7 +290,7 @@ void __dev_map_flush(struct bpf_map *map)
__clear_bit(bit, bitmap);
bq = this_cpu_ptr(dev->bulkq);
- bq_xmit_all(dev, bq, XDP_XMIT_FLUSH);
+ bq_xmit_all(dev, bq, XDP_XMIT_FLUSH, true);
}
}
@@ -316,7 +320,7 @@ static int bq_enqueue(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf,
struct xdp_bulk_queue *bq = this_cpu_ptr(obj->bulkq);
if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
- bq_xmit_all(obj, bq, 0);
+ bq_xmit_all(obj, bq, 0, true);
/* Ingress dev_rx will be the same for all xdp_frame's in
* bulk_queue, because bq stored per-CPU and must be flushed
@@ -385,7 +389,7 @@ static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
__clear_bit(dev->bit, bitmap);
bq = per_cpu_ptr(dev->bulkq, cpu);
- bq_xmit_all(dev, bq, XDP_XMIT_FLUSH);
+ bq_xmit_all(dev, bq, XDP_XMIT_FLUSH, false);
}
}
}
diff --git a/samples/bpf/xdp_redirect_cpu_kern.c b/samples/bpf/xdp_redirect_cpu_kern.c
index 303e9e7161f3..4938dcbaecbf 100644
--- a/samples/bpf/xdp_redirect_cpu_kern.c
+++ b/samples/bpf/xdp_redirect_cpu_kern.c
@@ -14,7 +14,7 @@
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"
-#define MAX_CPUS 12 /* WARNING - sync with _user.c */
+#define MAX_CPUS 64 /* WARNING - sync with _user.c */
/* Special map type that can XDP_REDIRECT frames to another CPU */
struct bpf_map_def SEC("maps") cpu_map = {
diff --git a/samples/bpf/xdp_redirect_cpu_user.c b/samples/bpf/xdp_redirect_cpu_user.c
index f6efaefd485b..4b4d78fffe30 100644
--- a/samples/bpf/xdp_redirect_cpu_user.c
+++ b/samples/bpf/xdp_redirect_cpu_user.c
@@ -19,7 +19,7 @@ static const char *__doc__ =
#include <arpa/inet.h>
#include <linux/if_link.h>
-#define MAX_CPUS 12 /* WARNING - sync with _kern.c */
+#define MAX_CPUS 64 /* WARNING - sync with _kern.c */
/* How many xdp_progs are defined in _kern.c */
#define MAX_PROG 5
@@ -527,7 +527,7 @@ static void stress_cpumap(void)
* procedure.
*/
create_cpu_entry(1, 1024, 0, false);
- create_cpu_entry(1, 128, 0, false);
+ create_cpu_entry(1, 8, 0, false);
create_cpu_entry(1, 16000, 0, false);
}