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| author | Peter Zijlstra <peterz@infradead.org> | 2021-01-12 11:24:04 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-07 15:37:17 +0100 |
| commit | b20475a80b4bd2c7bc720c3a9a8337c36b20dd8c (patch) | |
| tree | 07581d5d1b5afa67582357e311bbca9efedf51fd /include | |
| parent | d8649eb8e3521c39781aebf0597baee560ef7b79 (diff) | |
| download | linux-b20475a80b4bd2c7bc720c3a9a8337c36b20dd8c.tar.gz linux-b20475a80b4bd2c7bc720c3a9a8337c36b20dd8c.tar.bz2 linux-b20475a80b4bd2c7bc720c3a9a8337c36b20dd8c.zip | |
kthread: Extract KTHREAD_IS_PER_CPU
[ Upstream commit ac687e6e8c26181a33270efd1a2e2241377924b0 ]
There is a need to distinguish geniune per-cpu kthreads from kthreads
that happen to have a single CPU affinity.
Geniune per-cpu kthreads are kthreads that are CPU affine for
correctness, these will obviously have PF_KTHREAD set, but must also
have PF_NO_SETAFFINITY set, lest userspace modify their affinity and
ruins things.
However, these two things are not sufficient, PF_NO_SETAFFINITY is
also set on other tasks that have their affinities controlled through
other means, like for instance workqueues.
Therefore another bit is needed; it turns out kthread_create_per_cpu()
already has such a bit: KTHREAD_IS_PER_CPU, which is used to make
kthread_park()/kthread_unpark() work correctly.
Expose this flag and remove the implicit setting of it from
kthread_create_on_cpu(); the io_uring usage of it seems dubious at
best.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210121103506.557620262@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/kthread.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/kthread.h b/include/linux/kthread.h index 65b81e0c494d..2484ed97e72f 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -33,6 +33,9 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), unsigned int cpu, const char *namefmt); +void kthread_set_per_cpu(struct task_struct *k, int cpu); +bool kthread_is_per_cpu(struct task_struct *k); + /** * kthread_run - create and wake a thread. * @threadfn: the function to run until signal_pending(current). |