[PATCH RFC v1 02/10] m68k: use sched_clock() for random_get_entropy() instead of zero

From: Jason A. Donenfeld
Date: Fri Apr 08 2022 - 14:22:44 EST


In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling sched_clock() would be preferable, because
that always needs to return _something_, even falling back to jiffies
eventually. It's not as though sched_clock() is super high precision or
guaranteed to be entropic, but basically anything that's not zero all
the time is better than returning zero all the time.

Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
arch/m68k/include/asm/timex.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h
index 6a21d9358280..2cd0942097f8 100644
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -7,6 +7,8 @@
#ifndef _ASMm68K_TIMEX_H
#define _ASMm68K_TIMEX_H

+#include <linux/sched/clock.h>
+
#ifdef CONFIG_COLDFIRE
/*
* CLOCK_TICK_RATE should give the underlying frequency of the tick timer
@@ -35,7 +37,7 @@ static inline unsigned long random_get_entropy(void)
{
if (mach_random_get_entropy)
return mach_random_get_entropy();
- return 0;
+ return sched_clock();
}
#define random_get_entropy random_get_entropy

--
2.35.1