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Date:      Thu, 20 Jun 2019 20:29:43 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r349243 - head/sys/cam
Message-ID:  <201906202029.x5KKThjn017867@repo.freebsd.org>
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Author: mav
Date: Thu Jun 20 20:29:42 2019
New Revision: 349243
URL: https://svnweb.freebsd.org/changeset/base/349243

Log:
  Optimize xpt_getattr().
  
  Do not allocate temporary buffer for attributes we are going to return
  as-is, just make sure to NUL-terminate them.  Do not zero temporary 64KB
  buffer for CDAI_TYPE_SCSI_DEVID, XPT tells us how much data it filled
  and there are also length fields inside the returned data also.
  
  MFC after:	2 weeks
  Sponsored by:	iXsystems, Inc.

Modified:
  head/sys/cam/cam_xpt.c

Modified: head/sys/cam/cam_xpt.c
==============================================================================
--- head/sys/cam/cam_xpt.c	Thu Jun 20 20:06:19 2019	(r349242)
+++ head/sys/cam/cam_xpt.c	Thu Jun 20 20:29:42 2019	(r349243)
@@ -1253,6 +1253,7 @@ xpt_getattr(char *buf, size_t len, const char *attr, s
 	cdai.ccb_h.func_code = XPT_DEV_ADVINFO;
 	cdai.flags = CDAI_FLAG_NONE;
 	cdai.bufsiz = len;
+	cdai.buf = buf;
 
 	if (!strcmp(attr, "GEOM::ident"))
 		cdai.buftype = CDAI_TYPE_SERIAL_NUM;
@@ -1262,14 +1263,14 @@ xpt_getattr(char *buf, size_t len, const char *attr, s
 		 strcmp(attr, "GEOM::lunname") == 0) {
 		cdai.buftype = CDAI_TYPE_SCSI_DEVID;
 		cdai.bufsiz = CAM_SCSI_DEVID_MAXLEN;
+		cdai.buf = malloc(cdai.bufsiz, M_CAMXPT, M_NOWAIT);
+		if (cdai.buf == NULL) {
+			ret = ENOMEM;
+			goto out;
+		}
 	} else
 		goto out;
 
-	cdai.buf = malloc(cdai.bufsiz, M_CAMXPT, M_NOWAIT|M_ZERO);
-	if (cdai.buf == NULL) {
-		ret = ENOMEM;
-		goto out;
-	}
 	xpt_action((union ccb *)&cdai); /* can only be synchronous */
 	if ((cdai.ccb_h.status & CAM_DEV_QFRZN) != 0)
 		cam_release_devq(cdai.ccb_h.path, 0, 0, 0, FALSE);
@@ -1334,13 +1335,15 @@ xpt_getattr(char *buf, size_t len, const char *attr, s
 				ret = EFAULT;
 		}
 	} else {
-		ret = 0;
-		if (strlcpy(buf, cdai.buf, len) >= len)
+		if (cdai.provsiz < len) {
+			cdai.buf[cdai.provsiz] = 0;
+			ret = 0;
+		} else
 			ret = EFAULT;
 	}
 
 out:
-	if (cdai.buf != NULL)
+	if ((char *)cdai.buf != buf)
 		free(cdai.buf, M_CAMXPT);
 	return ret;
 }

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