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| author | Peter Zijlstra <peterz@infradead.org> | 2020-05-26 18:11:04 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-05-28 10:54:16 +0200 |
| commit | a148866489fbe243c936fe43e4525d8dbfa0318f (patch) | |
| tree | 5431e4fee20e79f58991f4c58161adf21b287ad5 /kernel/sched/sched.h | |
| parent | 126c2092e5c8b28623cb890cd2930aa292410676 (diff) | |
| download | linux-a148866489fbe243c936fe43e4525d8dbfa0318f.tar.bz2 | |
sched: Replace rq::wake_list
The recent commit: 90b5363acd47 ("sched: Clean up scheduler_ipi()")
got smp_call_function_single_async() subtly wrong. Even though it will
return -EBUSY when trying to re-use a csd, that condition is not
atomic and still requires external serialization.
The change in ttwu_queue_remote() got this wrong.
While on first reading ttwu_queue_remote() has an atomic test-and-set
that appears to serialize the use, the matching 'release' is not in
the right place to actually guarantee this serialization.
The actual race is vs the sched_ttwu_pending() call in the idle loop;
that can run the wakeup-list without consuming the CSD.
Instead of trying to chain the lists, merge them.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200526161908.129371594@infradead.org
Diffstat (limited to 'kernel/sched/sched.h')
| -rw-r--r-- | kernel/sched/sched.h | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c86fc94c54e5..1d4e94c1e5fe 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1023,11 +1023,6 @@ struct rq { unsigned int ttwu_local; #endif -#ifdef CONFIG_SMP - call_single_data_t wake_csd; - struct llist_head wake_list; -#endif - #ifdef CONFIG_CPU_IDLE /* Must be inspected within a rcu lock section */ struct cpuidle_state *idle_state; @@ -1371,8 +1366,6 @@ queue_balance_callback(struct rq *rq, rq->balance_callback = head; } -extern void sched_ttwu_pending(void); - #define rcu_dereference_check_sched_domain(p) \ rcu_dereference_check((p), \ lockdep_is_held(&sched_domains_mutex)) @@ -1512,7 +1505,6 @@ extern void flush_smp_call_function_from_idle(void); #else /* !CONFIG_SMP: */ static inline void flush_smp_call_function_from_idle(void) { } -static inline void sched_ttwu_pending(void) { } #endif #include "stats.h" |