| Andrew Geissler | d583833 | 2022-05-27 11:33:10 -0500 | [diff] [blame] | 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] fix: sched/tracing: Append prev_state to tp args instead |
| 5 | (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 | |
| 29 | Upstream-Status: Backport |
| 30 | |
| 31 | Change-Id: Ife2ec88a8bea2743562590cbd357068d7773863f |
| 32 | Signed-off-by: Michael Jeanson <mjeanson@efficios.com> |
| 33 | Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 34 | --- |
| 35 | include/instrumentation/events/sched.h | 6 +++--- |
| 36 | 1 file changed, 3 insertions(+), 3 deletions(-) |
| 37 | |
| 38 | diff --git a/include/instrumentation/events/sched.h b/include/instrumentation/events/sched.h |
| 39 | index 339bec94..c1c3df15 100644 |
| 40 | --- a/include/instrumentation/events/sched.h |
| 41 | +++ b/include/instrumentation/events/sched.h |
| 42 | @@ -356,11 +356,11 @@ LTTNG_TRACEPOINT_EVENT_INSTANCE(sched_wakeup_template, sched_wakeup_new, |
| 43 | LTTNG_TRACEPOINT_EVENT(sched_switch, |
| 44 | |
| 45 | TP_PROTO(bool preempt, |
| 46 | - unsigned int prev_state, |
| 47 | struct task_struct *prev, |
| 48 | - struct task_struct *next), |
| 49 | + struct task_struct *next, |
| 50 | + unsigned int prev_state), |
| 51 | |
| 52 | - TP_ARGS(preempt, prev_state, prev, next), |
| 53 | + TP_ARGS(preempt, prev, next, prev_state), |
| 54 | |
| 55 | TP_FIELDS( |
| 56 | ctf_array_text(char, prev_comm, prev->comm, TASK_COMM_LEN) |
| 57 | -- |
| 58 | 2.19.1 |
| 59 | |