from netbsd:

Fix a race condition where if a process is asleep waiting on an
exclusive lock of a ccd device while another process is unconfiguring
that same device, the first process would never awaken (unless interrupted).

diff --git a/sys/dev/ccd.c b/sys/dev/ccd.c
index df29bcf..c8d33a4 100644 (file)
--- a/sys/dev/ccd.c
+++ b/sys/dev/ccd.c
@@ -1,4 +1,4 @@
-/*     $NetBSD: ccd.c,v 1.18.2.2 1995/11/03 02:40:33 thorpej Exp $     */
+/*     $NetBSD: ccd.c,v 1.22 1995/12/08 19:13:26 thorpej Exp $ */
 
 /*
  * Copyright (c) 1995 Jason R. Thorpe.
@@ -945,7 +945,7 @@ ccdioctl(dev, cmd, data, flag, p)
 {
        int unit = ccdunit(dev);
        int i, j, lookedup = 0, error = 0;
-       int part, pmask;
+       int part, pmask, s;
        struct ccd_softc *cs;
        struct ccd_ioctl *ccio = (struct ccd_ioctl *)data;
        struct ccddevice ccd;
@@ -1093,6 +1093,8 @@ ccdioctl(dev, cmd, data, flag, p)
                /*
                 * Free ccd_softc information and clear entry.
                 */
+
+               /* Close the components and free their pathnames. */
                for (i = 0; i < cs->sc_nccdisks; ++i) {
                        /*
                         * XXX: this close could potentially fail and
@@ -1108,11 +1110,15 @@ ccdioctl(dev, cmd, data, flag, p)
                            p->p_ucred, p);
                        free(cs->sc_cinfo[i].ci_path, M_DEVBUF);
                }
+
+               /* Free interleave index. */
                for (i = 0; cs->sc_itable[i].ii_ndisk; ++i)
                        free(cs->sc_itable[i].ii_index, M_DEVBUF);
+
+               /* Free component info and interleave table. */
                free(cs->sc_cinfo, M_DEVBUF);
                free(cs->sc_itable, M_DEVBUF);
-               bzero(cs, sizeof(struct ccd_softc));
+               cs->sc_flags &= ~CCDF_INITED;
 
                /*
                 * Free ccddevice information and clear entry.
@@ -1122,7 +1128,11 @@ ccdioctl(dev, cmd, data, flag, p)
                ccd.ccd_dk = -1;
                bcopy(&ccd, &ccddevs[unit], sizeof(ccd));
 
+               /* This must be atomic. */
+               s = splhigh();
                ccdunlock(cs);
+               bzero(cs, sizeof(struct ccd_softc));
+               splx(s);
 
                break;