linux-kernel - [PATCH 2/3] lib: string_get_size: Use 32 bit arithmetic when possible

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Date:	Fri, 12 Dec 2014 15:43:47 +0100
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	James Bottomley <James.Bottomley@...senPartnership.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] lib: string_get_size: Use 32 bit arithmetic when possible

The remainder from do_div is always a u32, and after size has been
reduced to be below 1000 (or 1024), it certainly fits in u32. So both
remainder and sf_cap can be made u32s, the format specifiers can be
simplified (%lld wasn't the right thing to use for _unsigned_ long
long anyway), and we can replace a do_div with an ordinary 32/32 bit
division.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 lib/string_helpers.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 0d25f7aa732c..2b3757f84b3b 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -42,7 +42,7 @@ int string_get_size(u64 size, const enum string_size_units units,
 		[STRING_UNITS_2] = 1024,
 	};
 	int i, j;
-	u64 remainder = 0, sf_cap;
+	u32 remainder = 0, sf_cap;
 	char tmp[8];
 
 	tmp[0] = '\0';
@@ -59,14 +59,13 @@ int string_get_size(u64 size, const enum string_size_units units,
 
 		if (j) {
 			remainder *= 1000;
-			do_div(remainder, divisor[units]);
-			snprintf(tmp, sizeof(tmp), ".%03lld",
-				 (unsigned long long)remainder);
+			remainder /= divisor[units];
+			snprintf(tmp, sizeof(tmp), ".%03u", remainder);
 			tmp[j+1] = '\0';
 		}
 	}
 
-	snprintf(buf, len, "%lld%s %s", (unsigned long long)size,
+	snprintf(buf, len, "%u%s %s", (u32)size,
 		 tmp, units_str[units][i]);
 
 	return 0;
-- 
2.1.3

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