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Commit ef48bd246124ccdef0e1fa5b03b62d69cbf71fa7

Authored by Paul E. McKenney
Committed by Linus Torvalds
1 parent 4d3b573ad9
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

Document the fact that RCU callbacks can run in parallel 

Add an item to the RCU documentation checklist noting that RCU callbacks
can run in parallel.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 9 additions and 1 deletions Side-by-side Diff

Documentation/RCU/checklist.txt
Diff comments   View file @ ef48bd2
... ... @@ -222,7 +222,15 @@
222 222 deadlock as soon as the RCU callback happens to interrupt that
223 223 acquisition's critical section.
224 224  
225   -13. SRCU (srcu_read_lock(), srcu_read_unlock(), and synchronize_srcu())
  225 +13. RCU callbacks can be and are executed in parallel. In many cases,
  226 + the callback code simply wrappers around kfree(), so that this
  227 + is not an issue (or, more accurately, to the extent that it is
  228 + an issue, the memory-allocator locking handles it). However,
  229 + if the callbacks do manipulate a shared data structure, they
  230 + must use whatever locking or other synchronization is required
  231 + to safely access and/or modify that data structure.
  232 +
  233 +14. SRCU (srcu_read_lock(), srcu_read_unlock(), and synchronize_srcu())
226 234 may only be invoked from process context. Unlike other forms of
227 235 RCU, it -is- permissible to block in an SRCU read-side critical
228 236 section (demarked by srcu_read_lock() and srcu_read_unlock()),