Date: Wed, 2 Nov 2011 12:56:29 -0700 From: Navdeep Parhar <nparhar@gmail.com> To: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: incorrect parent refcounting in subr_firmware.c? Message-ID: <CAPFoGT9bLzAStkUnSfsBm0F6gmGuCM6kQRHQxa%2Bbsah4mQvQVw@mail.gmail.com>
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[-- Attachment #1 --]
I built a KLD with multiple firmware images, as shown here:
KMOD=foo
FIRMWS= foo.bin:foo:1.0.0.0
FIRMWS+=bar.bin:bar:1.0.0.0
FIRMWS+= ...
.include <bsd.kmod.mk>
"foo" is the parent firmware and a firmware_get(foo) can autoload the
KLD. "bar" and the rest are available only if the KLD is loaded (by
whatever means). This is reasonable and works as expected. But if I
just get and then put "foo" back, the KLD is not unloaded automatically.
The problem is that a reference is placed on the parent firmware when
the other firmwares are registered (during module load). I think this
reference should be placed during firmware_get on the child.
What do people think about the attached patch? It fixes things for me.
Regards,
Navdeep
[-- Attachment #2 --]
diff --git a/sys/kern/subr_firmware.c b/sys/kern/subr_firmware.c
--- a/sys/kern/subr_firmware.c
+++ b/sys/kern/subr_firmware.c
@@ -198,10 +198,8 @@
frp->fw.data = data;
frp->fw.datasize = datasize;
frp->fw.version = version;
- if (parent != NULL) {
+ if (parent != NULL)
frp->parent = PRIV_FW(parent);
- frp->parent->refcnt++;
- }
mtx_unlock(&firmware_mtx);
if (bootverbose)
printf("firmware: '%s' version %u: %zu bytes loaded at %p\n",
@@ -235,8 +233,6 @@
} else {
linker_file_t x = fp->file; /* save value */
- if (fp->parent != NULL) /* release parent reference */
- fp->parent->refcnt--;
/*
* Clear the whole entry with bzero to make sure we
* do not forget anything. Then restore 'file' which is
@@ -341,6 +337,8 @@
return NULL;
}
found: /* common exit point on success */
+ if (fp->refcnt == 0 && fp->parent != NULL)
+ fp->parent->refcnt++;
fp->refcnt++;
mtx_unlock(&firmware_mtx);
return &fp->fw;
@@ -363,6 +361,8 @@
mtx_lock(&firmware_mtx);
fp->refcnt--;
if (fp->refcnt == 0) {
+ if (fp->parent != NULL)
+ fp->parent->refcnt--;
if (flags & FIRMWARE_UNLOAD)
fp->flags |= FW_UNLOAD;
if (fp->file)
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