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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 /include/linux/sched.h | |
| parent | sched: Add rq::ttwu_pending (diff) | |
| download | wireguard-linux-a148866489fbe243c936fe43e4525d8dbfa0318f.tar.xz wireguard-linux-a148866489fbe243c936fe43e4525d8dbfa0318f.zip | |
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 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index ebc68706152a..e0f5f41cf2ee 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -654,6 +654,7 @@ struct task_struct { #ifdef CONFIG_SMP struct llist_node wake_entry; + unsigned int wake_entry_type; int on_cpu; #ifdef CONFIG_THREAD_INFO_IN_TASK /* Current CPU: */ |