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Commit 0612ea00a010e36fde61e7b7649a1105b0ef1080

Authored by Paul E. McKenney
Committed by Linus Torvalds
1 parent be50b8342d
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

rcu: documentation 1Q09 update 

Update the RCU documentation to call out the need for callers of
primitives like call_rcu() and synchronize_rcu() to prevent subsequent RCU
readers from hazard.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 12 additions and 0 deletions Side-by-side Diff

Documentation/RCU/checklist.txt
Diff comments   View file @ 0612ea0
... ... @@ -298,4 +298,16 @@
298 298  
299 299 Note that, rcu_assign_pointer() and rcu_dereference() relate to
300 300 SRCU just as they do to other forms of RCU.
  301 +
  302 +15. The whole point of call_rcu(), synchronize_rcu(), and friends
  303 + is to wait until all pre-existing readers have finished before
  304 + carrying out some otherwise-destructive operation. It is
  305 + therefore critically important to -first- remove any path
  306 + that readers can follow that could be affected by the
  307 + destructive operation, and -only- -then- invoke call_rcu(),
  308 + synchronize_rcu(), or friends.
  309 +
  310 + Because these primitives only wait for pre-existing readers,
  311 + it is the caller's responsibility to guarantee safety to
  312 + any subsequent readers.