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

Daniel Borkmann says:

====================
bpf-next 2022-11-02

We've added 70 non-merge commits during the last 14 day(s) which contain
a total of 96 files changed, 3203 insertions(+), 640 deletions(-).

The main changes are:

1) Make cgroup local storage available to non-cgroup attached BPF programs
   such as tc BPF ones, from Yonghong Song.

2) Avoid unnecessary deadlock detection and failures wrt BPF task storage
   helpers, from Martin KaFai Lau.

3) Add LLVM disassembler as default library for dumping JITed code
   in bpftool, from Quentin Monnet.

4) Various kprobe_multi_link fixes related to kernel modules,
   from Jiri Olsa.

5) Optimize x86-64 JIT with emitting BMI2-based shift instructions,
   from Jie Meng.

6) Improve BPF verifier's memory type compatibility for map key/value
   arguments, from Dave Marchevsky.

7) Only create mmap-able data section maps in libbpf when data is exposed
   via skeletons, from Andrii Nakryiko.

8) Add an autoattach option for bpftool to load all object assets,
   from Wang Yufen.

9) Various memory handling fixes for libbpf and BPF selftests,
   from Xu Kuohai.

10) Initial support for BPF selftest's vmtest.sh on arm64,
    from Manu Bretelle.

11) Improve libbpf's BTF handling to dedup identical structs,
    from Alan Maguire.

12) Add BPF CI and denylist documentation for BPF selftests,
    from Daniel Müller.

13) Check BPF cpumap max_entries before doing allocation work,
    from Florian Lehner.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (70 commits)
  samples/bpf: Fix typo in README
  bpf: Remove the obsolte u64_stats_fetch_*_irq() users.
  bpf: check max_entries before allocating memory
  bpf: Fix a typo in comment for DFS algorithm
  bpftool: Fix spelling mistake "disasembler" -> "disassembler"
  selftests/bpf: Fix bpftool synctypes checking failure
  selftests/bpf: Panic on hard/soft lockup
  docs/bpf: Add documentation for new cgroup local storage
  selftests/bpf: Add test cgrp_local_storage to DENYLIST.s390x
  selftests/bpf: Add selftests for new cgroup local storage
  selftests/bpf: Fix test test_libbpf_str/bpf_map_type_str
  bpftool: Support new cgroup local storage
  libbpf: Support new cgroup local storage
  bpf: Implement cgroup storage available to non-cgroup-attached bpf progs
  bpf: Refactor some inode/task/sk storage functions for reuse
  bpf: Make struct cgroup btf id global
  selftests/bpf: Tracing prog can still do lookup under busy lock
  selftests/bpf: Ensure no task storage failure for bpf_lsm.s prog due to deadlock detection
  bpf: Add new bpf_task_storage_delete proto with no deadlock detection
  bpf: bpf_task_storage_delete_recur does lookup first before the deadlock check
  ...
====================

Link: https://lore.kernel.org/r/20221102062120.5724-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 40 insertions, 3 deletions

diff --git a/tools/testing/selftests/bpf/progs/task_ls_recursion.c b/tools/testing/selftests/bpf/progs/task_ls_recursion.c
index 564583dca7c8..4542dc683b44 100644
--- a/tools/testing/selftests/bpf/progs/task_ls_recursion.c
+++ b/tools/testing/selftests/bpf/progs/task_ls_recursion.c
@@ -5,7 +5,13 @@
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 
+#ifndef EBUSY
+#define EBUSY 16
+#endif
+
 char _license[] SEC("license") = "GPL";
+int nr_del_errs = 0;
+int test_pid = 0;
 
 struct {
 	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
@@ -26,6 +32,13 @@ int BPF_PROG(on_lookup)
 {
 	struct task_struct *task = bpf_get_current_task_btf();
 
+	if (!test_pid || task->pid != test_pid)
+		return 0;
+
+	/* The bpf_task_storage_delete will call
+	 * bpf_local_storage_lookup.  The prog->active will
+	 * stop the recursion.
+	 */
 	bpf_task_storage_delete(&map_a, task);
 	bpf_task_storage_delete(&map_b, task);
 	return 0;
@@ -37,11 +50,32 @@ int BPF_PROG(on_update)
 	struct task_struct *task = bpf_get_current_task_btf();
 	long *ptr;
 
+	if (!test_pid || task->pid != test_pid)
+		return 0;
+
 	ptr = bpf_task_storage_get(&map_a, task, 0,
 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
-	if (ptr)
+	/* ptr will not be NULL when it is called from
+	 * the bpf_task_storage_get(&map_b,...F_CREATE) in
+	 * the BPF_PROG(on_enter) below.  It is because
+	 * the value can be found in map_a and the kernel
+	 * does not need to acquire any spin_lock.
+	 */
+	if (ptr) {
+		int err;
+
 		*ptr += 1;
+		err = bpf_task_storage_delete(&map_a, task);
+		if (err == -EBUSY)
+			nr_del_errs++;
+	}
 
+	/* This will still fail because map_b is empty and
+	 * this BPF_PROG(on_update) has failed to acquire
+	 * the percpu busy lock => meaning potential
+	 * deadlock is detected and it will fail to create
+	 * new storage.
+	 */
 	ptr = bpf_task_storage_get(&map_b, task, 0,
 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
 	if (ptr)
@@ -57,14 +91,17 @@ int BPF_PROG(on_enter, struct pt_regs *regs, long id)
 	long *ptr;
 
 	task = bpf_get_current_task_btf();
+	if (!test_pid || task->pid != test_pid)
+		return 0;
+
 	ptr = bpf_task_storage_get(&map_a, task, 0,
 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
-	if (ptr)
+	if (ptr && !*ptr)
 		*ptr = 200;
 
 	ptr = bpf_task_storage_get(&map_b, task, 0,
 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
-	if (ptr)
+	if (ptr && !*ptr)
 		*ptr = 100;
 	return 0;
 }