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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
To:     linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
        tglx@linutronix.de, arnd@arndb.de
Cc:     "Jason A. Donenfeld" <Jason@zx2c4.com>,
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        Will Deacon <will@kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
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Subject: [PATCH v2 03/11] m68k: use ktime_read_raw_clock() for random_get_entropy() instead of zero
Date:   Sun, 10 Apr 2022 23:49:43 +0200
Message-Id: <20220410214951.55294-4-Jason@zx2c4.com>
In-Reply-To: <20220410214951.55294-1-Jason@zx2c4.com>
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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 ktime_read_raw_clock() would be preferable,
because that always needs to return _something_, even falling back to
jiffies eventually. It's not as though ktime_read_raw_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: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/m68k/include/asm/timex.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h
index 6a21d9358280..5351b10e1b18 100644
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -35,7 +35,7 @@ static inline unsigned long random_get_entropy(void)
 {
 	if (mach_random_get_entropy)
 		return mach_random_get_entropy();
-	return 0;
+	return ktime_read_raw_clock();
 }
 #define random_get_entropy	random_get_entropy
 
-- 
2.35.1