proc: uninline name_to_int()

PATCH Applied Alexey Dobriyan 1 participant 2 messages Sep 12, 2017 Proc filesystem

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Alexey Dobriyan

author

2017-09-12 19:49 UTC #0 lore raw

PATCH 1/2 proc: uninline name_to_int()

Save ~360 bytes.

add/remove: 1/0 grow/shrink: 0/4 up/down: 104/-463 (-359)
function old new delta
name_to_int - 104 +104
proc_pid_lookup 217 126 -91
proc_lookupfd_common 212 121 -91
proc_task_lookup 289 194 -95
__proc_create 588 402 -186

Signed-off-by Alexey Dobriyan <[email protected]>

---

 fs/proc/Makefile   |    1 +
 fs/proc/internal.h |   23 +----------------------
 fs/proc/util.c     |   23 +++++++++++++++++++++++
 3 files changed, 25 insertions(+), 22 deletions(-)

fs/proc/Makefile +1 -0

@@ -20,6 +20,7 @@ proc-y	+= loadavg.o
 proc-y	+= meminfo.o
 proc-y	+= stat.o
 proc-y	+= uptime.o
+proc-y	+= util.o
 proc-y	+= version.o
 proc-y	+= softirqs.o
 proc-y	+= namespaces.o

fs/proc/internal.h +1 ~~-22~~

@@ -103,28 +103,7 @@ static inline struct task_struct *get_proc_task(struct inode *inode)
 void task_dump_owner(struct task_struct *task, mode_t mode,
 		     kuid_t *ruid, kgid_t *rgid);
 
-static inline unsigned name_to_int(const struct qstr *qstr)
-{
-	const char *name = qstr->name;
-	int len = qstr->len;
-	unsigned n = 0;
-
-	if (len > 1 && *name == '0')
-		goto out;
-	while (len-- > 0) {
-		unsigned c = *name++ - '0';
-		if (c > 9)
-			goto out;
-		if (n >= (~0U-9)/10)
-			goto out;
-		n *= 10;
-		n += c;
-	}
-	return n;
-out:
-	return ~0U;
-}
-
+unsigned name_to_int(const struct qstr *qstr);
 /*
  * Offset of the first process in the /proc root directory..
  */

fs/proc/util.c new file +23 -0

@@ -0,0 +1,23 @@
+#include <linux/dcache.h>
+
+unsigned name_to_int(const struct qstr *qstr)
+{
+	const char *name = qstr->name;
+	int len = qstr->len;
+	unsigned n = 0;
+
+	if (len > 1 && *name == '0')
+		goto out;
+	while (len-- > 0) {
+		unsigned c = *name++ - '0';
+		if (c > 9)
+			goto out;
+		if (n >= (~0U-9)/10)
+			goto out;
+		n *= 10;
+		n += c;
+	}
+	return n;
+out:
+	return ~0U;
+}

Alexey Dobriyan

author

2017-09-12 19:52 UTC #1 lore raw

PATCH 2/2 proc: use do-while in name_to_int()

Gcc doesn't know that "len" is guaranteed to be >=1 by dcache and generates standard while-loop prologue duplicating loop condition.

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-27 (-27)
function old new delta
name_to_int 104 77 -27

Signed-off-by Alexey Dobriyan <[email protected]>

---

 fs/proc/util.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

fs/proc/util.c +2 -2

@@ -8,7 +8,7 @@ unsigned name_to_int(const struct qstr *qstr)
 
 	if (len > 1 && *name == '0')
 		goto out;
-	while (len-- > 0) {
+	do {
 		unsigned c = *name++ - '0';
 		if (c > 9)
 			goto out;

@@ -16,7 +16,7 @@ unsigned name_to_int(const struct qstr *qstr)
 			goto out;
 		n *= 10;
 		n += c;
-	}
+	} while (--len > 0);
 	return n;
 out:
 	return ~0U;