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authorPeter Zijlstra <peterz@infradead.org>2021-01-12 11:24:04 +0100
committerPeter Zijlstra <peterz@infradead.org>2021-01-22 15:09:42 +0100
commitac687e6e8c26181a33270efd1a2e2241377924b0 (patch)
tree2409cb957d209a81666ccd573f8d64def03a8ff4 /include
parent22f667c97aadbf481e2cae2d6feabdf431e27b31 (diff)
downloadlinux-ac687e6e8c26181a33270efd1a2e2241377924b0.tar.bz2
kthread: Extract KTHREAD_IS_PER_CPU
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
Diffstat (limited to 'include')
-rw-r--r--include/linux/kthread.h3
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).