use a random number as the cookie in bio ioctls.

ok kn@ krw@

diff --git a/sys/dev/bio.c b/sys/dev/bio.c
index dba3ad4..9f9c4f8 100644 (file)
--- a/sys/dev/bio.c
+++ b/sys/dev/bio.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: bio.c,v 1.18 2023/11/09 14:07:18 dlg Exp $    */
+/*     $OpenBSD: bio.c,v 1.19 2023/11/15 23:57:45 dlg Exp $    */
 
 /*
  * Copyright (c) 2002 Niklas Hallqvist.  All rights reserved.
@@ -31,18 +31,33 @@
 #include <sys/device.h>
 #include <sys/ioctl.h>
 #include <sys/malloc.h>
-#include <sys/queue.h>
+#include <sys/tree.h>
 #include <sys/systm.h>
 
 #include <dev/biovar.h>
 
 struct bio_mapping {
-       LIST_ENTRY(bio_mapping) bm_link;
+       RBT_ENTRY(bio_mapping) bm_link;
+       uintptr_t bm_cookie;
        struct device *bm_dev;
        int (*bm_ioctl)(struct device *, u_long, caddr_t);
 };
 
-LIST_HEAD(, bio_mapping) bios = LIST_HEAD_INITIALIZER(bios);
+RBT_HEAD(bio_mappings, bio_mapping);
+
+static inline int
+bio_cookie_cmp(const struct bio_mapping *a, const struct bio_mapping *b)
+{
+       if (a->bm_cookie < b->bm_cookie)
+               return (1);
+       if (a->bm_cookie > b->bm_cookie)
+               return (-1);
+       return (0);
+}
+
+RBT_PROTOTYPE(bio_mappings, bio_mapping, bm_link, bio_cookie_cmp);
+
+struct bio_mappings bios = RBT_INITIALIZER();
 
 void   bioattach(int);
 int    bioclose(dev_t, int, int, struct proc *);
@@ -51,7 +66,7 @@ int   bioopen(dev_t, int, int, struct proc *);
 
 int    bio_delegate_ioctl(struct bio_mapping *, u_long, caddr_t);
 struct bio_mapping *bio_lookup(char *);
-int    bio_validate(void *);
+struct bio_mapping *bio_validate(void *);
 
 void
 bioattach(int nunits)
@@ -73,6 +88,7 @@ bioclose(dev_t dev, int flags, int mode, struct proc *p)
 int
 bioioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct proc *p)
 {
+       struct bio_mapping *bm;
        struct bio_locate *locate;
        struct bio *bio;
        char name[16];
@@ -84,18 +100,19 @@ bioioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct proc *p)
                error = copyinstr(locate->bl_name, name, sizeof name, NULL);
                if (error != 0)
                        return (error);
-               locate->bl_bio.bio_cookie = bio_lookup(name);
-               if (locate->bl_bio.bio_cookie == NULL)
+               bm = bio_lookup(name);
+               if (bm == NULL)
                        return (ENOENT);
+               locate->bl_bio.bio_cookie = (void *)bm->bm_cookie;
                break;
 
        default:
                bio = (struct bio *)addr;
-               if (!bio_validate(bio->bio_cookie))
+               bm = bio_validate(bio->bio_cookie);
+               if (bm == NULL)
                        return (ENOENT);
 
-               error = bio_delegate_ioctl(
-                   (struct bio_mapping *)bio->bio_cookie, cmd, addr);
+               error = bio_delegate_ioctl(bm, cmd, addr);
                break;
        }
 
@@ -112,7 +129,10 @@ bio_register(struct device *dev, int (*ioctl)(struct device *, u_long, caddr_t))
                return (ENOMEM);
        bm->bm_dev = dev;
        bm->bm_ioctl = ioctl;
-       LIST_INSERT_HEAD(&bios, bm, bm_link);
+       do {
+               bm->bm_cookie = arc4random();
+               /* lets hope we don't have 4 billion bio_registers */
+       } while (RBT_INSERT(bio_mappings, &bios, bm) != NULL);
        return (0);
 }
 
@@ -121,11 +141,9 @@ bio_unregister(struct device *dev)
 {
        struct bio_mapping *bm, *next;
 
-       for (bm = LIST_FIRST(&bios); bm != NULL; bm = next) {
-               next = LIST_NEXT(bm, bm_link);
-
+       RBT_FOREACH_SAFE(bm, bio_mappings, &bios, next) {
                if (dev == bm->bm_dev) {
-                       LIST_REMOVE(bm, bm_link);
+                       RBT_REMOVE(bio_mappings, &bios, bm);
                        free(bm, M_DEVBUF, sizeof(*bm));
                }
        }
@@ -136,21 +154,20 @@ bio_lookup(char *name)
 {
        struct bio_mapping *bm;
 
-       LIST_FOREACH(bm, &bios, bm_link)
+       RBT_FOREACH(bm, bio_mappings, &bios) {
                if (strcmp(name, bm->bm_dev->dv_xname) == 0)
                        return (bm);
+       }
+
        return (NULL);
 }
 
-int
+struct bio_mapping *
 bio_validate(void *cookie)
 {
-       struct bio_mapping *bm;
+       struct bio_mapping key = { .bm_cookie = (uintptr_t)cookie };
 
-       LIST_FOREACH(bm, &bios, bm_link)
-               if (bm == cookie)
-                       return (1);
-       return (0);
+       return (RBT_FIND(bio_mappings, &bios, &key));
 }
 
 int
@@ -218,3 +235,5 @@ bio_status(struct bio_status *bs, int print, int msg_type, const char *fmt,
        if (print)
                printf("%s: %s\n", bs->bs_controller, bs->bs_msgs[idx].bm_msg);
 }
+
+RBT_GENERATE(bio_mappings, bio_mapping, bm_link, bio_cookie_cmp);