srcu: Make SRCU be once again optional (07f6e64b) · Commits · 戴 / test

Commit ("srcu: Make SRCU be built by default") in response to build errors, which were caused by code that included srcu.h despite !SRCU. However, srcutiny.o is almost 2K of code, which is not insignificant for those attempting to run the Linux kernel on IoT devices. This commit therefore makes SRCU be once again optional, and adjusts srcu.h to allow error-free inclusion in !SRCU kernel builds. Signed-off-by:

Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by:

Nicolas Pitre <nico@linaro.org>

include/linux/srcu.h

+6 −1

Original line number	Diff line number	Diff line
		@@ -62,8 +62,13 @@ int init_srcu_struct(struct srcu_struct *sp);
		#include <linux/srcutree.h>
		#elif defined(CONFIG_CLASSIC_SRCU)
		#include <linux/srcuclassic.h>
		#else
		#elif defined(CONFIG_SRCU)
		#error "Unknown SRCU implementation specified to kernel configuration"
		#else

		/* Dummy definition for things like notifiers. Actual use gets link error. */
		struct srcu_struct { };

		#endif

		/**

init/Kconfig

+0 −1

Original line number	Diff line number	Diff line
		@@ -521,7 +521,6 @@ config RCU_EXPERT

		config SRCU
		bool
		default y
		help
		This option selects the sleepable version of RCU. This version
		permits arbitrary sleeping or blocking within RCU read-side critical

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