From: Chris Wright <chrisw@osdl.org>
To: blaisorblade_spam@yahoo.it
Cc: akpm@osdl.org, jdike@addtoit.com, linux-kernel@vger.kernel.org,
user-mode-linux-devel@lists.sourceforge.net
Subject: [uml-devel] Re: [patch 1/1] uml:fix ubd deadlock on SMP
Date: Wed, 8 Sep 2004 11:12:04 -0700 [thread overview]
Message-ID: <20040908111204.I1973@build.pdx.osdl.net> (raw)
In-Reply-To: <20040908172503.384144933@zion.localdomain>; from blaisorblade_spam@yahoo.it on Wed, Sep 08, 2004 at 07:25:02PM +0200
* 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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WARNING: multiple messages have this Message-ID (diff)
From: Chris Wright <chrisw@osdl.org>
To: blaisorblade_spam@yahoo.it
Cc: akpm@osdl.org, jdike@addtoit.com, linux-kernel@vger.kernel.org,
user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [patch 1/1] uml:fix ubd deadlock on SMP
Date: Wed, 8 Sep 2004 11:12:04 -0700 [thread overview]
Message-ID: <20040908111204.I1973@build.pdx.osdl.net> (raw)
In-Reply-To: <20040908172503.384144933@zion.localdomain>; from blaisorblade_spam@yahoo.it on Wed, Sep 08, 2004 at 07:25:02PM +0200
* 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
next prev parent reply other threads:[~2004-09-08 18:12 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-08 17:25 [uml-devel] [patch 1/1] uml:fix ubd deadlock on SMP blaisorblade_spam
2004-09-08 17:25 ` blaisorblade_spam
2004-09-08 18:12 ` Chris Wright [this message]
2004-09-08 18:12 ` Chris Wright
2004-09-09 18:02 ` [uml-devel] " BlaisorBlade
2004-09-09 18:02 ` BlaisorBlade
2004-09-09 18:32 ` Chris Wright
2004-09-09 18:32 ` Chris Wright
2004-09-09 18:44 ` BlaisorBlade
2004-09-09 18:44 ` BlaisorBlade
2004-09-09 19:29 ` Chris Wright
2004-09-09 19:29 ` Chris Wright
2004-09-10 19:01 ` BlaisorBlade
2004-09-10 19:01 ` BlaisorBlade
2004-09-09 7:35 ` Jens Axboe
2004-09-09 7:35 ` Jens Axboe
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