Messages in this thread Patch in this message | | | From | Valentin Schneider <> | Subject | [RFC PATCH v2 7/8] smp: reword smp call IPI comment | Date | Wed, 2 Nov 2022 18:33:35 +0000 |
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Accessing the call_single_queue hasn't involved a spinlock since 2014:
6897fc22ea01 ("kernel: use lockless list for smp_call_function_single")
The llist operations (namely cmpxchg() and xchg()) provide similar ordering guarantees, update the comment to lessen confusion.
Signed-off-by: Valentin Schneider <vschneid@redhat.com> --- kernel/smp.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c index 44fa4b9b1f46b..b96579fe08f09 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -503,9 +503,10 @@ void __smp_call_single_queue(int cpu, struct llist_node *node) #endif /* - * The list addition should be visible before sending the IPI - * handler locks the list to pull the entry off it because of - * normal cache coherency rules implied by spinlocks. + * The list addition should be visible to the target CPU when it pops + * the head of the list to pull the entry off it in the IPI handler + * because of normal cache coherency rules implied by the underlying + * llist ops. * * If IPIs can go out of order to the cache coherency protocol * in an architecture, sufficient synchronisation should be added -- 2.31.1
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