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SubjectRe: [patch 1/1] uml:fix ubd deadlock on SMP
* blaisorblade_spam@yahoo.it (blaisorblade_spam@yahoo.it) wrote:
>
> Trivial: don't lock the queue spinlock when called from the request function.
> Since the faulty function must use spinlock in another case, double-case it.
> And since we will never use both functions together, let no object code be
> shared between them.

Why not add a helper which locks around the core function. Then either
call helper or core function directly depending on locking needs?

Smth. along the lines of below.

===== arch/um/drivers/ubd_kern.c 1.36 vs edited =====
--- 1.36/arch/um/drivers/ubd_kern.c 2004-08-24 02:08:18 -07:00
+++ edited/arch/um/drivers/ubd_kern.c 2004-09-08 11:06:54 -07:00
@@ -396,14 +396,20 @@
*/
int intr_count = 0;

-static void ubd_finish(struct request *req, int error)
+static inline void ubd_finish(struct request *req, int error)
+{
+ spin_lock(&ubd_io_lock);
+ __ubd_finish(req, error);
+ spin_unlock(&ubd_io_lock);
+}
+
+/* call ubd_finish if you need to serialize */
+static void __ubd_finish(struct request *req, int error)
{
int nsect;

if(error){
- spin_lock(&ubd_io_lock);
end_request(req, 0);
- spin_unlock(&ubd_io_lock);
return;
}
nsect = req->current_nr_sectors;
@@ -412,9 +418,7 @@
req->errors = 0;
req->nr_sectors -= nsect;
req->current_nr_sectors = 0;
- spin_lock(&ubd_io_lock);
end_request(req, 1);
- spin_unlock(&ubd_io_lock);
}

static void ubd_handler(void)
--
Linux Security Modules http://lsm.immunix.org http://lsm.bkbits.net
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