Commit 4c9fbff5 authored by Martin KaFai Lau's avatar Martin KaFai Lau
Browse files

Merge branch 'Two fixes for cpu-map' 



Hou Tao says:

====================

The patchset fixes two reported warning in cpu-map when running
xdp_redirect_cpu and some RT threads concurrently. Patch #1 fixes
the warning in __cpu_map_ring_cleanup() when kthread is stopped
prematurely. Patch #2 fixes the warning in __xdp_return() when
there are pending skbs in ptr_ring.

Please see individual patches for more details. And comments are always
welcome.

====================

Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parents bcc29b7f 7c62b75c

kernel/bpf/cpumap.c

+21 −14
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/sched.h>

#include <linux/workqueue.h>

#include <linux/kthread.h>

#include <linux/completion.h>

#include <trace/events/xdp.h>

#include <linux/btf_ids.h>
@@ -73,6 +74,7 @@ struct bpf_cpu_map_entry { 
	struct rcu_head rcu;



	struct work_struct kthread_stop_wq;

	struct completion kthread_running;

};



struct bpf_cpu_map {
@@ -129,11 +131,17 @@ static void __cpu_map_ring_cleanup(struct ptr_ring *ring) 
	 * invoked cpu_map_kthread_stop(). Catch any broken behaviour

	 * gracefully and warn once.

	 */

	struct xdp_frame *xdpf;

	void *ptr;



	while ((xdpf = ptr_ring_consume(ring)))

		if (WARN_ON_ONCE(xdpf))

			xdp_return_frame(xdpf);

	while ((ptr = ptr_ring_consume(ring))) {

		WARN_ON_ONCE(1);

		if (unlikely(__ptr_test_bit(0, &ptr))) {

			__ptr_clear_bit(0, &ptr);

			kfree_skb(ptr);

			continue;

		}

		xdp_return_frame(ptr);

	}

}



static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu)
@@ -153,7 +161,6 @@ static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) 
static void cpu_map_kthread_stop(struct work_struct *work)

{

	struct bpf_cpu_map_entry *rcpu;

	int err;



	rcpu = container_of(work, struct bpf_cpu_map_entry, kthread_stop_wq);
@@ -163,14 +170,7 @@ static void cpu_map_kthread_stop(struct work_struct *work) 
	rcu_barrier();



	/* kthread_stop will wake_up_process and wait for it to complete */

	err = kthread_stop(rcpu->kthread);

	if (err) {

		/* kthread_stop may be called before cpu_map_kthread_run

		 * is executed, so we need to release the memory related

		 * to rcpu.

		 */

		put_cpu_map_entry(rcpu);

	}

	kthread_stop(rcpu->kthread);

}



static void cpu_map_bpf_prog_run_skb(struct bpf_cpu_map_entry *rcpu,
@@ -298,11 +298,11 @@ static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames, 
	return nframes;

}





static int cpu_map_kthread_run(void *data)

{

	struct bpf_cpu_map_entry *rcpu = data;



	complete(&rcpu->kthread_running);

	set_current_state(TASK_INTERRUPTIBLE);



	/* When kthread gives stop order, then rcpu have been disconnected
@@ -467,6 +467,7 @@ __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value, 
		goto free_ptr_ring;



	/* Setup kthread */

	init_completion(&rcpu->kthread_running);

	rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa,

					       "cpumap/%d/map:%d", cpu,

					       map->id);
@@ -480,6 +481,12 @@ __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value, 
	kthread_bind(rcpu->kthread, cpu);

	wake_up_process(rcpu->kthread);



	/* Make sure kthread has been running, so kthread_stop() will not

	 * stop the kthread prematurely and all pending frames or skbs

	 * will be handled by the kthread before kthread_stop() returns.

	 */

	wait_for_completion(&rcpu->kthread_running);



	return rcpu;



free_prog: