Messages in this thread Patch in this message | | | From | Milos Vyletel <> | Subject | [PATCH] rcu: small rcu_dereference doc update | Date | Fri, 17 Apr 2015 12:33:36 +0200 |
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Make a note stating that repeated calls of rcu_dereference() may not return the same pointer if update happens while in critical section.
Reported-by: Jeff Haran <jeff.haran@citrix.com> Signed-off-by: Milos Vyletel <milos@redhat.com> --- Documentation/RCU/whatisRCU.txt | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 88dfce1..82b1b2c 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -256,7 +256,9 @@ rcu_dereference() If you are going to be fetching multiple fields from the RCU-protected structure, using the local variable is of course preferred. Repeated rcu_dereference() calls look - ugly and incur unnecessary overhead on Alpha CPUs. + ugly, do not guarantee that same pointer will be returned + if update happened while in critical section and incur + unnecessary overhead on Alpha CPUs. Note that the value returned by rcu_dereference() is valid only within the enclosing RCU read-side critical section. -- 2.1.0
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