Messages in this thread Patch in this message | | | Date | Tue, 11 Oct 2022 16:45:38 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v8 6/7] apei/ghes: Use unrcu_pointer for cmpxchg |
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On Tue, Oct 11, 2022 at 02:32:48PM +0000, Justin He wrote: > My original purpose is to make it pass the sparse checking.
Then do this pls.
This is a combined diff - do a second patch which does only remove the smp_wmb(). The smp_wmb() there is not needed as the cmpxchg() already implies a smp_mb() so there's no need for that separate, explicit one.
But it would be prudent to have it in a separate patch just in case.
Thx.
--- diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 85acfc589fb7..fd285bf8d114 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -154,7 +154,7 @@ struct ghes_vendor_record_entry { static struct gen_pool *ghes_estatus_pool; static unsigned long ghes_estatus_pool_size_request; -static struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE]; +static struct ghes_estatus_cache __rcu *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE]; static atomic_t ghes_estatus_cache_alloced; static int ghes_panic_timeout __read_mostly = 30; @@ -842,9 +842,7 @@ static void ghes_estatus_cache_add( slot_cache = cache; } } - /* new_cache must be put into array after its contents are written */ - smp_wmb(); - if (slot != -1 && cmpxchg(ghes_estatus_caches + slot, + if (slot != -1 && cmpxchg((struct ghes_estatus_cache ** __force)(ghes_estatus_caches + slot), slot_cache, new_cache) == slot_cache) { if (slot_cache) call_rcu(&slot_cache->rcu, ghes_estatus_cache_rcu_free); -- Regards/Gruss, Boris.
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