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[PATCH 1/2] drivers/rtc: use %ph for short hex dumps

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  [PATCH 1/2] drivers/rtc: use %ph for short hex dumps Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2015-11-24 15:00 +0100
    [PATCH 2/2] drivers/rtc/rtc-ds1685.c: don't try to micromanage sysfs output size Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2015-11-24 15:00 +0100

#1276489 — [PATCH 1/2] drivers/rtc: use %ph for short hex dumps

This makes the generated code slightly smaller.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/rtc/rtc-ds1305.c |  8 ++------
 drivers/rtc/rtc-ds1307.c | 17 ++++-------------
 drivers/rtc/rtc-ds1685.c | 12 +++++-------
 3 files changed, 11 insertions(+), 26 deletions(-)

diff --git a/drivers/rtc/rtc-ds1305.c b/drivers/rtc/rtc-ds1305.c
index 85706a9f82c9..f39691eea736 100644
--- a/drivers/rtc/rtc-ds1305.c
+++ b/drivers/rtc/rtc-ds1305.c
@@ -186,9 +186,7 @@ static int ds1305_get_time(struct device *dev, struct rtc_time *time)
 	if (status < 0)
 		return status;
 
-	dev_vdbg(dev, "%s: %02x %02x %02x, %02x %02x %02x %02x\n",
-		"read", buf[0], buf[1], buf[2], buf[3],
-		buf[4], buf[5], buf[6]);
+	dev_vdbg(dev, "%s: %3ph, %4ph\n", "read", &buf[0], &buf[3]);
 
 	/* Decode the registers */
 	time->tm_sec = bcd2bin(buf[DS1305_SEC]);
@@ -232,9 +230,7 @@ static int ds1305_set_time(struct device *dev, struct rtc_time *time)
 	*bp++ = bin2bcd(time->tm_mon + 1);
 	*bp++ = bin2bcd(time->tm_year - 100);
 
-	dev_dbg(dev, "%s: %02x %02x %02x, %02x %02x %02x %02x\n",
-		"write", buf[1], buf[2], buf[3],
-		buf[4], buf[5], buf[6], buf[7]);
+	dev_dbg(dev, "%s: %3ph, %4ph\n", "write", &buf[1], &buf[4]);
 
 	/* use write-then-read since dma from stack is nonportable */
 	return spi_write_then_read(ds1305->spi, buf, sizeof(buf),
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 188006c55ce0..b72e782fbf44 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -464,13 +464,8 @@ static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 		return -EIO;
 	}
 
-	dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
-			"alarm read",
-			ds1307->regs[0], ds1307->regs[1],
-			ds1307->regs[2], ds1307->regs[3],
-			ds1307->regs[4], ds1307->regs[5],
-			ds1307->regs[6], ds1307->regs[7],
-			ds1307->regs[8]);
+	dev_dbg(dev, "%s: %4ph, %3ph, %2ph\n", "alarm read",
+		&ds1307->regs[0], &ds1307->regs[4], &ds1307->regs[7]);
 
 	/*
 	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
@@ -526,12 +521,8 @@ static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 	control = ds1307->regs[7];
 	status = ds1307->regs[8];
 
-	dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
-			"alarm set (old status)",
-			ds1307->regs[0], ds1307->regs[1],
-			ds1307->regs[2], ds1307->regs[3],
-			ds1307->regs[4], ds1307->regs[5],
-			ds1307->regs[6], control, status);
+	dev_dbg(dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
+		&ds1307->regs[0], &ds1307->regs[4], control, status);
 
 	/* set ALARM1, using 24 hour and day-of-month modes */
 	buf[0] = bin2bcd(t->time.tm_sec);
diff --git a/drivers/rtc/rtc-ds1685.c b/drivers/rtc/rtc-ds1685.c
index 05a51ef52703..5038122aa8de 100644
--- a/drivers/rtc/rtc-ds1685.c
+++ b/drivers/rtc/rtc-ds1685.c
@@ -853,7 +853,7 @@ ds1685_rtc_proc(struct device *dev, struct seq_file *seq)
 	   "Periodic Rate\t: %s\n"
 	   "SQW Freq\t: %s\n"
 #ifdef CONFIG_RTC_DS1685_PROC_REGS
-	   "Serial #\t: %02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n"
+	   "Serial #\t: %8phC\n"
 	   "Register Status\t:\n"
 	   "   Ctrl A\t: UIP  DV2  DV1  DV0  RS3  RS2  RS1  RS0\n"
 	   "\t\t:  %s\n"
@@ -872,7 +872,7 @@ ds1685_rtc_proc(struct device *dev, struct seq_file *seq)
 	   "   Ctrl 4B\t: ABE  E32k  CS  RCE  PRS  RIE  WIE  KSE\n"
 	   "\t\t:  %s\n",
 #else
-	   "Serial #\t: %02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
+	   "Serial #\t: %8phC\n",
 #endif
 	   model,
 	   ((ctrla & RTC_CTRL_A_DV1) ? "enabled" : "disabled"),
@@ -888,7 +888,7 @@ ds1685_rtc_proc(struct device *dev, struct seq_file *seq)
 	   (!((ctrl4b & RTC_CTRL_4B_E32K)) ?
 	    ds1685_rtc_sqw_freq[(ctrla & RTC_CTRL_A_RS_MASK)] : "32768Hz"),
 #ifdef CONFIG_RTC_DS1685_PROC_REGS
-	   ssn[0], ssn[1], ssn[2], ssn[3], ssn[4], ssn[5], ssn[6], ssn[7],
+	   ssn,
 	   ds1685_rtc_print_regs(ctrla, bits[0]),
 	   ds1685_rtc_print_regs(ctrlb, bits[1]),
 	   ds1685_rtc_print_regs(ctrlc, bits[2]),
@@ -896,7 +896,7 @@ ds1685_rtc_proc(struct device *dev, struct seq_file *seq)
 	   ds1685_rtc_print_regs(ctrl4a, bits[4]),
 	   ds1685_rtc_print_regs(ctrl4b, bits[5]));
 #else
-	   ssn[0], ssn[1], ssn[2], ssn[3], ssn[4], ssn[5], ssn[6], ssn[7]);
+	   ssn);
 #endif
 	return 0;
 }
@@ -1160,9 +1160,7 @@ ds1685_rtc_sysfs_serial_show(struct device *dev,
 	ds1685_rtc_get_ssn(rtc, ssn);
 	ds1685_rtc_switch_to_bank0(rtc);
 
-	return snprintf(buf, 24, "%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
-			ssn[0], ssn[1], ssn[2], ssn[3], ssn[4], ssn[5],
-			ssn[6], ssn[7]);
+	return snprintf(buf, 24, "%8phC\n", ssn);
 
 	return 0;
 }
-- 
2.6.1

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#1276491 — [PATCH 2/2] drivers/rtc/rtc-ds1685.c: don't try to micromanage sysfs output size

...and don't do it wrong.

"not ok or N/A" has length 13. Add the trailing newline, and the
snprintf return value will be 14. However, we lied to snprintf and
told it that only 13 bytes were available. Hence snprintf has only
written "not ok or N/" and a trailing '\0' to the buffer. Next we
continue lying, this time to the upper sysfs layer, claiming that we
wrote 14 meaningful bytes to the buffer. That'll make the upper layer
copy "not ok or N/" plus two nul bytes to user space (one nul byte
from snprintf, the other since sysfs takes care to clear the buffer
before giving it to the ->show method).

In the other cases, the claimed buffer size is closer to sufficient,
but we'll still get a nul byte instead of a newline written to user
space.  There's absolutely no reason to try to predict the output
size, and there's plenty of room in the buffer, so just use sprintf.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/rtc/rtc-ds1685.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-ds1685.c b/drivers/rtc/rtc-ds1685.c
index 5038122aa8de..535050fc5e9f 100644
--- a/drivers/rtc/rtc-ds1685.c
+++ b/drivers/rtc/rtc-ds1685.c
@@ -1114,7 +1114,7 @@ ds1685_rtc_sysfs_battery_show(struct device *dev,
 
 	ctrld = rtc->read(rtc, RTC_CTRL_D);
 
-	return snprintf(buf, 13, "%s\n",
+	return sprintf(buf, "%s\n",
 			(ctrld & RTC_CTRL_D_VRT) ? "ok" : "not ok or N/A");
 }
 static DEVICE_ATTR(battery, S_IRUGO, ds1685_rtc_sysfs_battery_show, NULL);
@@ -1137,7 +1137,7 @@ ds1685_rtc_sysfs_auxbatt_show(struct device *dev,
 	ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
 	ds1685_rtc_switch_to_bank0(rtc);
 
-	return snprintf(buf, 13, "%s\n",
+	return sprintf(buf, "%s\n",
 			(ctrl4a & RTC_CTRL_4A_VRT2) ? "ok" : "not ok or N/A");
 }
 static DEVICE_ATTR(auxbatt, S_IRUGO, ds1685_rtc_sysfs_auxbatt_show, NULL);
@@ -1160,9 +1160,7 @@ ds1685_rtc_sysfs_serial_show(struct device *dev,
 	ds1685_rtc_get_ssn(rtc, ssn);
 	ds1685_rtc_switch_to_bank0(rtc);
 
-	return snprintf(buf, 24, "%8phC\n", ssn);
-
-	return 0;
+	return sprintf(buf, "%8phC\n", ssn);
 }
 static DEVICE_ATTR(serial, S_IRUGO, ds1685_rtc_sysfs_serial_show, NULL);
 
@@ -1285,7 +1283,7 @@ ds1685_rtc_sysfs_ctrl_regs_show(struct device *dev,
 	tmp = rtc->read(rtc, reg_info->reg) & reg_info->bit;
 	ds1685_rtc_switch_to_bank0(rtc);
 
-	return snprintf(buf, 2, "%d\n", (tmp ? 1 : 0));
+	return sprintf(buf, "%d\n", (tmp ? 1 : 0));
 }
 
 /**
@@ -1621,7 +1619,7 @@ ds1685_rtc_sysfs_time_regs_show(struct device *dev,
 	tmp = ds1685_rtc_bcd2bin(rtc, tmp, bcd_reg_info->mask,
 				 bin_reg_info->mask);
 
-	return snprintf(buf, 4, "%d\n", tmp);
+	return sprintf(buf, "%d\n", tmp);
 }
 
 /**
-- 
2.6.1

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