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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
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
This commit is contained in:
Thomas Gleixner 2020-02-14 14:39:19 +01:00 committed by Alibek Omarov
parent a7cda995da
commit 54c6cc4bbe
1 changed files with 7 additions and 0 deletions
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7
include/linux/kernel.h
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@ -271,6 +271,13 @@ 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.