0013-fix-sched-tracing-Append-prev_state-to-tp-args-inste.patch

   1 From 9c5b8de32b5745f3ff31079c02da64595e101bee Mon Sep 17 00:00:00 2001
   2 From: Michael Jeanson <mjeanson@efficios.com>
   3 Date: Tue, 17 May 2022 11:46:29 -0400
   4 Subject: [PATCH 13/13] fix: sched/tracing: Append prev_state to tp args
   5  instead (v5.18)
   6
   7 See upstream commit :
   8
   9   commit 9c2136be0878c88c53dea26943ce40bb03ad8d8d
  10   Author: Delyan Kratunov <delyank@fb.com>
  11   Date:   Wed May 11 18:28:36 2022 +0000
  12
  13     sched/tracing: Append prev_state to tp args instead
  14
  15     Commit fa2c3254d7cf (sched/tracing: Don't re-read p->state when emitting
  16     sched_switch event, 2022-01-20) added a new prev_state argument to the
  17     sched_switch tracepoint, before the prev task_struct pointer.
  18
  19     This reordering of arguments broke BPF programs that use the raw
  20     tracepoint (e.g. tp_btf programs). The type of the second argument has
  21     changed and existing programs that assume a task_struct* argument
  22     (e.g. for bpf_task_storage access) will now fail to verify.
  23
  24     If we instead append the new argument to the end, all existing programs
  25     would continue to work and can conditionally extract the prev_state
  26     argument on supported kernel versions.
  27
  28 Change-Id: Ife2ec88a8bea2743562590cbd357068d7773863f
  29 Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
  30 Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  31 ---
  32  include/instrumentation/events/sched.h | 6 +++---
  33  1 file changed, 3 insertions(+), 3 deletions(-)
  34
  35 diff --git a/include/instrumentation/events/sched.h b/include/instrumentation/events/sched.h
  36 index 339bec94..c1c3df15 100644
  37 --- a/include/instrumentation/events/sched.h
  38 +++ b/include/instrumentation/events/sched.h
  39 @@ -356,11 +356,11 @@ LTTNG_TRACEPOINT_EVENT_INSTANCE(sched_wakeup_template, sched_wakeup_new,
  40  LTTNG_TRACEPOINT_EVENT(sched_switch,
  41
  42         TP_PROTO(bool preempt,
  43 -               unsigned int prev_state,
  44                 struct task_struct *prev,
  45 -               struct task_struct *next),
  46 +               struct task_struct *next,
  47 +               unsigned int prev_state),
  48
  49 -       TP_ARGS(preempt, prev_state, prev, next),
  50 +       TP_ARGS(preempt, prev, next, prev_state),
  51
  52         TP_FIELDS(
  53                 ctf_array_text(char, prev_comm, prev->comm, TASK_COMM_LEN)
  54 --
  55 2.36.1
  56