Commit 4e139c77 authored Feb 14, 2020 by Thomas Gleixner

sched: Provide cant_migrate()



Some code pathes rely on preempt_disable() to prevent migration on a non RT
enabled kernel. These preempt_disable/enable() pairs are substituted by
migrate_disable/enable() pairs or other forms of RT specific protection. On
RT these protections prevent migration but not preemption. Obviously a
cant_sleep() check in such a section will trigger on RT because preemption
is not disabled.

Provide a cant_migrate() macro which maps to cant_sleep() on a non RT
kernel and an empty placeholder for RT for now. The placeholder will be
changed to a proper debug check along with the RT specific migration
protection mechanism.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200214161503.070487511@linutronix.de

parent 66630058

include/linux/kernel.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -257,6 +257,13 @@ extern void __cant_sleep(const char *file, int line, int preempt_offset);

		#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)

		#ifndef CONFIG_PREEMPT_RT
		# define cant_migrate() cant_sleep()
		#else
		/* Placeholder for now */
		# define cant_migrate() do { } while (0)
		#endif

		/**
		* abs - return absolute value of an argument
		* @x: the value. If it is unsigned type, it is converted to signed type first.

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