Hi Alexander, I’m not a fan of removing the M_ZERO. I understand your argument that lengths are provided elsewhere, but having the buffer be zero’d is defensive against future bugs that might leak buffer contents. GETATTR isn’t typically in a performance path, is there any measurable benefit to this?
Thanks, Scott > On Jun 20, 2019, at 2:29 PM, Alexander Motin <m...@freebsd.org> wrote: > > 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; > } > _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
