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Date:      Thu, 30 Jul 2020 15:47:41 +0000 (UTC)
From:      Mateusz Guzik <mjg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r363706 - in head/sys: kern sys
Message-ID:  <202007301547.06UFlf5J099795@repo.freebsd.org>
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Author: mjg
Date: Thu Jul 30 15:47:41 2020
New Revision: 363706
URL: https://svnweb.freebsd.org/changeset/base/363706

Log:
  vfs: short-circuit the common case NDFREE calls
  
  Almost all consumers use the NDF_ONLY_PNBUF macro, making them avoidably branch
  a lot in the NDFREE routine. Also note most of them should not need to call
  any cleanup anyway as they don't request HASBUF.

Modified:
  head/sys/kern/vfs_lookup.c
  head/sys/sys/namei.h

Modified: head/sys/kern/vfs_lookup.c
==============================================================================
--- head/sys/kern/vfs_lookup.c	Thu Jul 30 15:45:11 2020	(r363705)
+++ head/sys/kern/vfs_lookup.c	Thu Jul 30 15:47:41 2020	(r363706)
@@ -1390,18 +1390,26 @@ NDINIT_ALL(struct nameidata *ndp, u_long op, u_long fl
  * Free data allocated by namei(); see namei(9) for details.
  */
 void
-NDFREE(struct nameidata *ndp, const u_int flags)
+NDFREE_PNBUF(struct nameidata *ndp)
 {
+
+	if ((ndp->ni_cnd.cn_flags & HASBUF) != 0) {
+		uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
+		ndp->ni_cnd.cn_flags &= ~HASBUF;
+	}
+}
+
+void
+(NDFREE)(struct nameidata *ndp, const u_int flags)
+{
 	int unlock_dvp;
 	int unlock_vp;
 
 	unlock_dvp = 0;
 	unlock_vp = 0;
 
-	if (!(flags & NDF_NO_FREE_PNBUF) &&
-	    (ndp->ni_cnd.cn_flags & HASBUF)) {
-		uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
-		ndp->ni_cnd.cn_flags &= ~HASBUF;
+	if (!(flags & NDF_NO_FREE_PNBUF)) {
+		NDFREE_PNBUF(ndp);
 	}
 	if (!(flags & NDF_NO_VP_UNLOCK) &&
 	    (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)

Modified: head/sys/sys/namei.h
==============================================================================
--- head/sys/sys/namei.h	Thu Jul 30 15:45:11 2020	(r363705)
+++ head/sys/sys/namei.h	Thu Jul 30 15:47:41 2020	(r363706)
@@ -210,7 +210,15 @@ void NDINIT_ALL(struct nameidata *ndp, u_long op, u_lo
 #define NDF_NO_FREE_PNBUF	0x00000020
 #define NDF_ONLY_PNBUF		(~NDF_NO_FREE_PNBUF)
 
+void NDFREE_PNBUF(struct nameidata *);
 void NDFREE(struct nameidata *, const u_int);
+#define NDFREE(ndp, flags) do {						\
+	struct nameidata *_ndp = (ndp);					\
+	if (__builtin_constant_p(flags) && flags == NDF_ONLY_PNBUF)	\
+		NDFREE_PNBUF(_ndp);					\
+	else								\
+		NDFREE(_ndp, flags);					\
+} while (0)
 
 int	namei(struct nameidata *ndp);
 int	lookup(struct nameidata *ndp);

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