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From: Mateusz Guzik <mjg@FreeBSD.org>
Date: Sat, 11 Nov 2017 21:50:36 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r325725 - head/sys/kern
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Author: mjg
Date: Sat Nov 11 21:50:36 2017
New Revision: 325725
URL: https://svnweb.freebsd.org/changeset/base/325725

Log:
  sysctl: try to avoid malloc in name2oid
  
  name2oid is called all the time and passed names are almost always very short
  (< 16 characters).

Modified:
  head/sys/kern/kern_sysctl.c

Modified: head/sys/kern/kern_sysctl.c
==============================================================================
--- head/sys/kern/kern_sysctl.c	Sat Nov 11 20:12:48 2017	(r325724)
+++ head/sys/kern/kern_sysctl.c	Sat Nov 11 21:50:36 2017	(r325725)
@@ -1209,17 +1209,21 @@ sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
 	int error, oid[CTL_MAXNAME], len = 0;
 	struct sysctl_oid *op = NULL;
 	struct rm_priotracker tracker;
+	char buf[32];
 
 	if (!req->newlen) 
 		return (ENOENT);
 	if (req->newlen >= MAXPATHLEN)	/* XXX arbitrary, undocumented */
 		return (ENAMETOOLONG);
 
-	p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);
+	p = buf;
+	if (req->newlen >= sizeof(buf))
+		p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);
 
 	error = SYSCTL_IN(req, p, req->newlen);
 	if (error) {
-		free(p, M_SYSCTL);
+		if (p != buf)
+			free(p, M_SYSCTL);
 		return (error);
 	}
 
@@ -1229,7 +1233,8 @@ sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
 	error = name2oid(p, oid, &len, &op);
 	SYSCTL_RUNLOCK(&tracker);
 
-	free(p, M_SYSCTL);
+	if (p != buf)
+		free(p, M_SYSCTL);
 
 	if (error)
 		return (error);