linux-kernel - [PATCH] uapi: linux: acct: Remove redundant type comp2

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Date:   Wed,  5 Oct 2016 21:40:10 +0800
From:   chengang@...ndsoft.com.cn
To:     akpm@...ux-foundation.org, dhowells@...hat.com
Cc:     linux-kernel@...r.kernel.org,
        Chen Gang <chengang@...ndsoft.com.cn>,
        Chen Gang <gang.chen.5i5j@...il.com>
Subject: [PATCH] uapi: linux: acct: Remove redundant type comp2_t from kernel

From: Chen Gang <chengang@...ndsoft.com.cn>

In api itself, kernel does not use it -- it is divided into ac_etime_hi
and ac_etime_lo. So kernel side only need generate the correct
ac_etime_hi and ac_etime_lo, but need not know about comp2_t.

At present, kernel use normal u64 type for it, when kernel provdes it to
outside, kernel can translate it into ac_etime_hi and ac_etime_lo,
directly, but need not notice about comp2_t, in fact.

The patch notices about coding styles:

 - Use 1 instead of 1ul, since type int is enough.

 - Use white space between operator and constant or macro.

 - Initialize variables directly, when declare it, since they need be
   initialized and can be initialized by constant (include constant
   macros).

 - Remove redundant empty line.

Signed-off-by: Chen Gang <gang.chen.5i5j@...il.com>
---
 include/uapi/linux/acct.h |  6 ++++--
 kernel/acct.c             | 31 ++++++++++++++-----------------
 2 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/include/uapi/linux/acct.h b/include/uapi/linux/acct.h
index df2f9a0..97acdd4 100644
--- a/include/uapi/linux/acct.h
+++ b/include/uapi/linux/acct.h
@@ -24,12 +24,15 @@
  *  comp_t is a 16-bit "floating" point number with a 3-bit base 8
  *  exponent and a 13-bit fraction.
  *  comp2_t is 24-bit with 5-bit base 2 exponent and 20 bit fraction
- *  (leading 1 not stored).
+ *  (leading 1 not stored). And it is described as ac_etime_hi and
+ *  ac_etime_lo in kernel.
  *  See linux/kernel/acct.c for the specific encoding systems used.
  */
 
 typedef __u16	comp_t;
+#ifndef __KERNEL__
 typedef __u32	comp2_t;
+#endif	/* __KERNEL */
 
 /*
  *   accounting file record
@@ -120,5 +123,4 @@ struct acct_v3
 #define AHZ		(HZ)
 #endif	/* __KERNEL */
 
-
 #endif /* _UAPI_LINUX_ACCT_H */
diff --git a/kernel/acct.c b/kernel/acct.c
index 74963d1..f707a10 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -338,7 +338,7 @@ static comp_t encode_comp_t(unsigned long value)
 
 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
 /*
- * encode an u64 into a comp2_t (24 bits)
+ * encode an u64 into ac_etime_hi and ac_etime_lo (24 bits)
  *
  * Format: 5 bit base 2 exponent, 20 bits mantissa.
  * The leading bit of the mantissa is not stored, but implied for
@@ -348,15 +348,15 @@ static comp_t encode_comp_t(unsigned long value)
 
 #define MANTSIZE2       20                      /* 20 bit mantissa. */
 #define EXPSIZE2        5                       /* 5 bit base 2 exponent. */
-#define MAXFRACT2       ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
-#define MAXEXP2         ((1 << EXPSIZE2) - 1)    /* Maximum exponent. */
+#define MAXFRACT2       ((1 << MANTSIZE2) - 1)  /* Maximum fractional value. */
+#define MAXEXP2         ((1 << EXPSIZE2) - 1)   /* Maximum exponent. */
 
-static comp2_t encode_comp2_t(u64 value)
+static void encode_ac_etime_hilo(u64 value, acct_t *ac)
 {
-	int exp, rnd;
+	int exp = (value > (MAXFRACT2 >> 1));
+	int rnd = 0;
+	u32 etime;
 
-	exp = (value > (MAXFRACT2>>1));
-	rnd = 0;
 	while (value > MAXFRACT2) {
 		rnd = value & 1;
 		value >>= 1;
@@ -373,10 +373,12 @@ static comp2_t encode_comp2_t(u64 value)
 
 	if (exp > MAXEXP2) {
 		/* Overflow. Return largest representable number instead. */
-		return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
+		etime = (1 << (MANTSIZE2 + EXPSIZE2 - 1)) - 1;
 	} else {
-		return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
+		etime = (value & (MAXFRACT2 >> 1)) | (exp << (MANTSIZE2 - 1));
 	}
+	ac->ac_etime_hi = etime >> 16;
+	ac->ac_etime_lo = (u16) etime;
 }
 #endif
 
@@ -436,17 +438,12 @@ static void fill_ac(acct_t *ac)
 				(unsigned long) elapsed : (unsigned long) -1l);
 #endif
 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
-	{
-		/* new enlarged etime field */
-		comp2_t etime = encode_comp2_t(elapsed);
-
-		ac->ac_etime_hi = etime >> 16;
-		ac->ac_etime_lo = (u16) etime;
-	}
+	/* new enlarged etime field */
+	encode_ac_etime_hilo(elapsed, ac);
 #endif
 	do_div(elapsed, AHZ);
 	ac->ac_btime = get_seconds() - elapsed;
-#if ACCT_VERSION==2
+#if ACCT_VERSION == 2
 	ac->ac_ahz = AHZ;
 #endif
 
-- 
1.9.3