Merge tag 'for-netdev' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
pull-request: bpf-next 2023-10-26

We've added 51 non-merge commits during the last 10 day(s) which contain
a total of 75 files changed, 5037 insertions(+), 200 deletions(-).

The main changes are:

1) Add open-coded task, css_task and css iterator support.
   One of the use cases is customizable OOM victim selection via BPF,
   from Chuyi Zhou.

2) Fix BPF verifier's iterator convergence logic to use exact states
   comparison for convergence checks, from Eduard Zingerman,
   Andrii Nakryiko and Alexei Starovoitov.

3) Add BPF programmable net device where bpf_mprog defines the logic
   of its xmit routine. It can operate in L3 and L2 mode,
   from Daniel Borkmann and Nikolay Aleksandrov.

4) Batch of fixes for BPF per-CPU kptr and re-enable unit_size checking
   for global per-CPU allocator, from Hou Tao.

5) Fix libbpf which eagerly assumed that SHT_GNU_verdef ELF section
   was going to be present whenever a binary has SHT_GNU_versym section,
   from Andrii Nakryiko.

6) Fix BPF ringbuf correctness to fold smp_mb__before_atomic() into
   atomic_set_release(), from Paul E. McKenney.

7) Add a warning if NAPI callback missed xdp_do_flush() under
   CONFIG_DEBUG_NET which helps checking if drivers were missing
   the former, from Sebastian Andrzej Siewior.

8) Fix missed RCU read-lock in bpf_task_under_cgroup() which was throwing
   a warning under sleepable programs, from Yafang Shao.

9) Avoid unnecessary -EBUSY from htab_lock_bucket by disabling IRQ before
   checking map_locked, from Song Liu.

10) Make BPF CI linked_list failure test more robust,
    from Kumar Kartikeya Dwivedi.

11) Enable samples/bpf to be built as PIE in Fedora, from Viktor Malik.

12) Fix xsk starving when multiple xsk sockets were associated with
    a single xsk_buff_pool, from Albert Huang.

13) Clarify the signed modulo implementation for the BPF ISA standardization
    document that it uses truncated division, from Dave Thaler.

14) Improve BPF verifier's JEQ/JNE branch taken logic to also consider
    signed bounds knowledge, from Andrii Nakryiko.

15) Add an option to XDP selftests to use multi-buffer AF_XDP
    xdp_hw_metadata and mark used XDP programs as capable to use frags,
    from Larysa Zaremba.

16) Fix bpftool's BTF dumper wrt printing a pointer value and another
    one to fix struct_ops dump in an array, from Manu Bretelle.

* tag 'for-netdev' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (51 commits)
  netkit: Remove explicit active/peer ptr initialization
  selftests/bpf: Fix selftests broken by mitigations=off
  samples/bpf: Allow building with custom bpftool
  samples/bpf: Fix passing LDFLAGS to libbpf
  samples/bpf: Allow building with custom CFLAGS/LDFLAGS
  bpf: Add more WARN_ON_ONCE checks for mismatched alloc and free
  selftests/bpf: Add selftests for netkit
  selftests/bpf: Add netlink helper library
  bpftool: Extend net dump with netkit progs
  bpftool: Implement link show support for netkit
  libbpf: Add link-based API for netkit
  tools: Sync if_link uapi header
  netkit, bpf: Add bpf programmable net device
  bpf: Improve JEQ/JNE branch taken logic
  bpf: Fold smp_mb__before_atomic() into atomic_set_release()
  bpf: Fix unnecessary -EBUSY from htab_lock_bucket
  xsk: Avoid starving the xsk further down the list
  bpf: print full verifier states on infinite loop detection
  selftests/bpf: test if state loops are detected in a tricky case
  bpf: correct loop detection for iterators convergence
  ...
====================

Link: https://lore.kernel.org/r/20231026150509.2824-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 52 insertions, 0 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index a37a932a3e14..0d548431f3fa 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6530,6 +6530,8 @@ static int __napi_poll(struct napi_struct *n, bool *repoll)
 	if (napi_is_scheduled(n)) {
 		work = n->poll(n, weight);
 		trace_napi_poll(n, work, weight);
+
+		xdp_do_check_flushed(n);
 	}
 
 	if (unlikely(work > weight))
diff --git a/net/core/dev.h b/net/core/dev.h
index fa2e9c5c4122..5aa45f0fd4ae 100644
--- a/net/core/dev.h
+++ b/net/core/dev.h
@@ -139,4 +139,10 @@ static inline void netif_set_gro_ipv4_max_size(struct net_device *dev,
 }
 
 int rps_cpumask_housekeeping(struct cpumask *mask);
+
+#if defined(CONFIG_DEBUG_NET) && defined(CONFIG_BPF_SYSCALL)
+void xdp_do_check_flushed(struct napi_struct *napi);
+#else
+static inline void xdp_do_check_flushed(struct napi_struct *napi) { }
+#endif
 #endif
diff --git a/net/core/filter.c b/net/core/filter.c
index cc2e4babc85f..21d75108c2e9 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -83,6 +83,8 @@
 #include <net/netfilter/nf_conntrack_bpf.h>
 #include <linux/un.h>
 
+#include "dev.h"
+
 static const struct bpf_func_proto *
 bpf_sk_base_func_proto(enum bpf_func_id func_id);
 
@@ -4208,6 +4210,20 @@ void xdp_do_flush(void)
 }
 EXPORT_SYMBOL_GPL(xdp_do_flush);
 
+#if defined(CONFIG_DEBUG_NET) && defined(CONFIG_BPF_SYSCALL)
+void xdp_do_check_flushed(struct napi_struct *napi)
+{
+	bool ret;
+
+	ret = dev_check_flush();
+	ret |= cpu_map_check_flush();
+	ret |= xsk_map_check_flush();
+
+	WARN_ONCE(ret, "Missing xdp_do_flush() invocation after NAPI by %ps\n",
+		  napi->poll);
+}
+#endif
+
 void bpf_clear_redirect_map(struct bpf_map *map)
 {
 	struct bpf_redirect_info *ri;
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index f5e96e0d6e01..ae9f8cb611f6 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -33,6 +33,7 @@
 #include "xsk.h"
 
 #define TX_BATCH_SIZE 32
+#define MAX_PER_SOCKET_BUDGET (TX_BATCH_SIZE)
 
 static DEFINE_PER_CPU(struct list_head, xskmap_flush_list);
 
@@ -391,6 +392,16 @@ void __xsk_map_flush(void)
 	}
 }
 
+#ifdef CONFIG_DEBUG_NET
+bool xsk_map_check_flush(void)
+{
+	if (list_empty(this_cpu_ptr(&xskmap_flush_list)))
+		return false;
+	__xsk_map_flush();
+	return true;
+}
+#endif
+
 void xsk_tx_completed(struct xsk_buff_pool *pool, u32 nb_entries)
 {
 	xskq_prod_submit_n(pool->cq, nb_entries);
@@ -413,16 +424,25 @@ EXPORT_SYMBOL(xsk_tx_release);
 
 bool xsk_tx_peek_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc)
 {
+	bool budget_exhausted = false;
 	struct xdp_sock *xs;
 
 	rcu_read_lock();
+again:
 	list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list) {
+		if (xs->tx_budget_spent >= MAX_PER_SOCKET_BUDGET) {
+			budget_exhausted = true;
+			continue;
+		}
+
 		if (!xskq_cons_peek_desc(xs->tx, desc, pool)) {
 			if (xskq_has_descs(xs->tx))
 				xskq_cons_release(xs->tx);
 			continue;
 		}
 
+		xs->tx_budget_spent++;
+
 		/* This is the backpressure mechanism for the Tx path.
 		 * Reserve space in the completion queue and only proceed
 		 * if there is space in it. This avoids having to implement
@@ -436,6 +456,14 @@ bool xsk_tx_peek_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc)
 		return true;
 	}
 
+	if (budget_exhausted) {
+		list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list)
+			xs->tx_budget_spent = 0;
+
+		budget_exhausted = false;
+		goto again;
+	}
+
 out:
 	rcu_read_unlock();
 	return false;