Commit-ID: 677df9d4615a2db6774cd0e8951bf7404b858b3b Gitweb: http://git.kernel.org/tip/677df9d4615a2db6774cd0e8951bf7404b858b3b Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Sun, 23 Apr 2017 09:22:05 -0700 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Mon, 24 Apr 2017 08:14:48 +0200 srcu: Fix Kconfig botch when SRCU not selected If the CONFIG_SRCU option is not selected, for example, when building arch/tile allnoconfig, the following build errors appear: kernel/rcu/tree.o: In function `srcu_online_cpu': tree.c:(.text+0x4248): multiple definition of `srcu_online_cpu' kernel/rcu/srcutree.o:srcutree.c:(.text+0x2120): first defined here kernel/rcu/tree.o: In function `srcu_offline_cpu': tree.c:(.text+0x4250): multiple definition of `srcu_offline_cpu' kernel/rcu/srcutree.o:srcutree.c:(.text+0x2160): first defined here The corresponding .config file shows CONFIG_TREE_SRCU=y, but no sign of CONFIG_SRCU, which fatally confuses SRCU's #ifdefs, resulting in the above errors. The reason this occurs is the folowing line in init/Kconfig's definition for TREE_SRCU: default y if !TINY_RCU && !CLASSIC_SRCU If CONFIG_CLASSIC_SRCU=n, as it will be in for allnoconfig, and if CONFIG_SMP=y, then we will get CONFIG_TREE_SRCU=y but no CONFIG_SRCU, as seen in the .config file, and which will result in the above errors. This error did not show up during rcutorture testing because rcutorture forces CONFIG_SRCU=y, as it must to prevent build errors in rcutorture.c. This commit therefore conditions TREE_SRCU (and TINY_SRCU, while it is at it) with SRCU, like this: default y if SRCU && !TINY_RCU && !CLASSIC_SRCU Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx> Reported-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20170423162205.GP3956@xxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- init/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index 4119a44..fe72c12 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -545,13 +545,13 @@ config CLASSIC_SRCU config TINY_SRCU bool - default y if TINY_RCU && !CLASSIC_SRCU + default y if SRCU && TINY_RCU && !CLASSIC_SRCU help This option selects the single-CPU non-preemptible version of SRCU. config TREE_SRCU bool - default y if !TINY_RCU && !CLASSIC_SRCU + default y if SRCU && !TINY_RCU && !CLASSIC_SRCU help This option selects the full-fledged version of SRCU. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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