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Message-Id: <20221102183336.3120536-6-vschneid@redhat.com>
Date: Wed, 2 Nov 2022 18:33:35 +0000
From: Valentin Schneider <vschneid@...hat.com>
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Cc: "Paul E. McKenney" <paulmck@...nel.org>,
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Nicholas Piggin <npiggin@...il.com>,
Guo Ren <guoren@...nel.org>,
"David S. Miller" <davem@...emloft.net>
Subject: [RFC PATCH v2 7/8] smp: reword smp call IPI comment
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@...hat.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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