[PATCH bpf-next 0/9] bpf: Avoid unnecessary deadlock detection and failure in task storage

[Martin KaFai Lau <martin.lau@xxxxxxxxx>]

From: Martin KaFai Lau <martin.lau@xxxxxxxxxx>

The commit bc235cdb423a ("bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]")
added deadlock detection to avoid a tracing program from recurring
on the bpf_task_storage_{get,delete}() helpers.  These helpers acquire
a spin lock and it will lead to deadlock.

It is unnecessary for the bpf_lsm and bpf_iter programs which do
not recur.  The situation is the same as the existing
bpf_pid_task_storage_{lookup,delete}_elem() which are
used in the syscall and they also do not have deadlock detection.

This set is to add new bpf_task_storage_{get,delete}() helper proto
without the deadlock detection.  The set also removes the prog->active
check from the bpf_lsm and bpf_iter program.  Please see the individual
patch for details.

Martin KaFai Lau (9):
  bpf: Remove prog->active check for bpf_lsm and bpf_iter
  bpf: Append _recur naming to the bpf_task_storage helper proto
  bpf: Refactor the core bpf_task_storage_get logic into a new function
  bpf: Avoid taking spinlock in bpf_task_storage_get if potential
    deadlock is detected
  bpf: Add new bpf_task_storage_get proto with no deadlock detection
  bpf: bpf_task_storage_delete_recur does lookup first before the
    deadlock check
  bpf: Add new bpf_task_storage_delete proto with no deadlock detection
  selftests/bpf: Ensure no task storage failure for bpf_lsm.s prog due
    to deadlock detection
  selftests/bpf: Tracing prog can still do lookup under busy lock

 arch/arm64/net/bpf_jit_comp.c                 |   9 +-
 arch/x86/net/bpf_jit_comp.c                   |  19 +--
 include/linux/bpf.h                           |  26 ++--
 include/linux/bpf_verifier.h                  |  15 +-
 kernel/bpf/bpf_local_storage.c                |   1 +
 kernel/bpf/bpf_task_storage.c                 | 119 +++++++++++---
 kernel/bpf/syscall.c                          |   5 +-
 kernel/bpf/trampoline.c                       |  80 ++++++++--
 kernel/trace/bpf_trace.c                      |   5 +
 .../bpf/prog_tests/task_local_storage.c       | 146 +++++++++++++++++-
 .../selftests/bpf/progs/task_ls_recursion.c   |  43 +++++-
 .../bpf/progs/task_storage_nodeadlock.c       |  47 ++++++
 12 files changed, 431 insertions(+), 84 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/task_storage_nodeadlock.c

-- 
2.30.2