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| author | Peter Zijlstra <peterz@infradead.org> | 2021-01-12 13:24:04 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-07 16:47:41 +0300 |
| commit | a9b2e4a94eee352e0b3e863045e7379d83131ee2 (patch) | |
| tree | 09c0e7ec0fe0609194684b5c7e1de306658e8398 /include/linux/kthread.h | |
| parent | 536aea4013d50a4768262430e30c047818e57380 (diff) | |
| download | linux-a9b2e4a94eee352e0b3e863045e7379d83131ee2.tar.xz | |
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/linux/kthread.h')
| -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 4e26609c77d4..eb305353f20f 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -31,6 +31,9 @@ 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). |