svn commit: r325725 - head/sys/kern

[Mateusz Guzik]

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);
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