git: 7f9867f8c65b - main - linuxkpi: do not destroy/free embedded linux cdevs

[Konstantin Belousov]

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=7f9867f8c65b1b3e590dba4dc432a4bc8cf01f68

commit 7f9867f8c65b1b3e590dba4dc432a4bc8cf01f68
Author:     Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2021-03-30 08:44:19 +0000
Commit:     Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2021-04-06 00:38:29 +0000

    linuxkpi: do not destroy/free embedded linux cdevs
    
    They have their own lifetime managed by the containing objects.
    Premature and unexpected free causes corruption.
    
    Reviewed by:    hselasky
    Sponsored by:   Mellanox Technologies/NVidia Networking
    MFC after:      1 week
---
 sys/compat/linuxkpi/common/src/linux_compat.c      | 13 ++++++++++---
 sys/compat/linuxkpi/common/src/linux_compat.c.orig |  6 +++---
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/sys/compat/linuxkpi/common/src/linux_compat.c b/sys/compat/linuxkpi/common/src/linux_compat.c
index 0731859e7a53..71ea7e0844dc 100644
--- a/sys/compat/linuxkpi/common/src/linux_compat.c
+++ b/sys/compat/linuxkpi/common/src/linux_compat.c
@@ -2199,8 +2199,8 @@ linux_completion_done(struct completion *c)
 static void
 linux_cdev_deref(struct linux_cdev *ldev)
 {
-
-	if (refcount_release(&ldev->refs))
+	if (refcount_release(&ldev->refs) &&
+	    ldev->kobj.ktype == &linux_cdev_ktype)
 		kfree(ldev);
 }
 
@@ -2220,12 +2220,17 @@ linux_cdev_release(struct kobject *kobj)
 static void
 linux_cdev_static_release(struct kobject *kobj)
 {
+	struct cdev *cdev;
 	struct linux_cdev *ldev;
 	struct kobject *parent;
 
 	ldev = container_of(kobj, struct linux_cdev, kobj);
 	parent = kobj->parent;
-	linux_destroy_dev(ldev);
+	cdev = ldev->cdev;
+	if (cdev != NULL) {
+		destroy_dev(cdev);
+		ldev->cdev = NULL;
+	}
 	kobject_put(parent);
 }
 
@@ -2237,6 +2242,8 @@ linux_destroy_dev(struct linux_cdev *ldev)
 		return;
 
 	MPASS((ldev->siref & LDEV_SI_DTR) == 0);
+	MPASS(ldev->kobj.ktype == &linux_cdev_ktype);
+
 	atomic_set_int(&ldev->siref, LDEV_SI_DTR);
 	while ((atomic_load_int(&ldev->siref) & ~LDEV_SI_DTR) != 0)
 		pause("ldevdtr", hz / 4);
diff --git a/sys/compat/linuxkpi/common/src/linux_compat.c.orig b/sys/compat/linuxkpi/common/src/linux_compat.c.orig
index b7a7ba8b4f18..0731859e7a53 100644
--- a/sys/compat/linuxkpi/common/src/linux_compat.c.orig
+++ b/sys/compat/linuxkpi/common/src/linux_compat.c.orig
@@ -2220,12 +2220,12 @@ linux_cdev_release(struct kobject *kobj)
 static void
 linux_cdev_static_release(struct kobject *kobj)
 {
-	struct linux_cdev *cdev;
+	struct linux_cdev *ldev;
 	struct kobject *parent;
 
-	cdev = container_of(kobj, struct linux_cdev, kobj);
+	ldev = container_of(kobj, struct linux_cdev, kobj);
 	parent = kobj->parent;
-	linux_destroy_dev(cdev);
+	linux_destroy_dev(ldev);
 	kobject_put(parent);
 }