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| author | Peter Zijlstra <peterz@infradead.org> | 2020-05-26 19:11:04 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-05-28 11:54:16 +0300 |
| commit | a148866489fbe243c936fe43e4525d8dbfa0318f (patch) | |
| tree | 5431e4fee20e79f58991f4c58161adf21b287ad5 /include/linux/smp.h | |
| parent | 126c2092e5c8b28623cb890cd2930aa292410676 (diff) | |
| download | linux-a148866489fbe243c936fe43e4525d8dbfa0318f.tar.xz | |
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/smp.h')
| -rw-r--r-- | include/linux/smp.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/smp.h b/include/linux/smp.h index 45ad6e30f398..84f90e24ed6f 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -25,6 +25,7 @@ enum { CSD_TYPE_ASYNC = 0x00, CSD_TYPE_SYNC = 0x10, CSD_TYPE_IRQ_WORK = 0x20, + CSD_TYPE_TTWU = 0x30, CSD_FLAG_TYPE_MASK = 0xF0, }; |