diff options
| author | zhidao su <suzhidao@xiaomi.com> | 2026-03-03 14:09:58 +0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-03-02 22:00:02 -1000 |
| commit | 3f27958b729a2337336a6b50e0d9aee5fbbce816 (patch) | |
| tree | e284368b1e7f66ded01e3e0b138c096f5b450d8d /kernel | |
| parent | 494eaf4651975127d34d5ae6555c72dedba092c9 (diff) | |
sched_ext: Use READ_ONCE() for plain reads of scx_watchdog_timeout
scx_watchdog_timeout is written with WRITE_ONCE() in scx_enable():
WRITE_ONCE(scx_watchdog_timeout, timeout);
However, three read-side accesses use plain reads without the matching
READ_ONCE():
/* check_rq_for_timeouts() - L2824 */
last_runnable + scx_watchdog_timeout
/* scx_watchdog_workfn() - L2852 */
scx_watchdog_timeout / 2
/* scx_enable() - L5179 */
scx_watchdog_timeout / 2
The KCSAN documentation requires that if one accessor uses WRITE_ONCE()
to annotate lock-free access, all other accesses must also use the
appropriate accessor. Plain reads alongside WRITE_ONCE() leave the pair
incomplete and can trigger KCSAN warnings.
Note that scx_tick() already uses the correct READ_ONCE() annotation:
last_check + READ_ONCE(scx_watchdog_timeout)
Fix the three remaining plain reads to match, making all accesses to
scx_watchdog_timeout consistently annotated and KCSAN-clean.
Signed-off-by: zhidao su <suzhidao@xiaomi.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/ext.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index a566d2cc8a43..2ba69b302368 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -2739,7 +2739,7 @@ static bool check_rq_for_timeouts(struct rq *rq) unsigned long last_runnable = p->scx.runnable_at; if (unlikely(time_after(jiffies, - last_runnable + scx_watchdog_timeout))) { + last_runnable + READ_ONCE(scx_watchdog_timeout)))) { u32 dur_ms = jiffies_to_msecs(jiffies - last_runnable); scx_exit(sch, SCX_EXIT_ERROR_STALL, 0, @@ -2767,7 +2767,7 @@ static void scx_watchdog_workfn(struct work_struct *work) cond_resched(); } queue_delayed_work(system_unbound_wq, to_delayed_work(work), - scx_watchdog_timeout / 2); + READ_ONCE(scx_watchdog_timeout) / 2); } void scx_tick(struct rq *rq) @@ -5081,7 +5081,7 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link) WRITE_ONCE(scx_watchdog_timeout, timeout); WRITE_ONCE(scx_watchdog_timestamp, jiffies); queue_delayed_work(system_unbound_wq, &scx_watchdog_work, - scx_watchdog_timeout / 2); + READ_ONCE(scx_watchdog_timeout) / 2); /* * Once __scx_enabled is set, %current can be switched to SCX anytime. |