From: Milos Vyletel Date: Fri, 17 Apr 2015 14:38:04 +0000 (+0200) Subject: documentation: State that rcu_dereference() reloads pointer X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ed38446424dd531f1b7a167677232a6d400d69d5;p=linux-beck.git documentation: State that rcu_dereference() reloads pointer 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 Signed-off-by: Milos Vyletel Reviewed-by: Steven Rostedt Signed-off-by: Paul E. McKenney --- diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 88dfce182f66..16622c9e86b5 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 the same pointer will be returned + if an update happened while in the 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.