2012-06-12 17:40:58

by Ben Chan

Subject: [PATCH v2] staging: gdm72xx: Fix spinlock recursion on gdm_usb_send_complete

This patch fixes a spinlock recursion bug on several call sites of
gdm_usb_send_complete by not calling spin_lock_irqsave on
urb->context->tx_cxt->lock when the lock has already been acquired.

Signed-off-by: Ben Chan <[email protected]>
Cc: Sage Ahn <[email protected]>
---
This revised patch simplifies the previous patch.

drivers/staging/gdm72xx/gdm_usb.c | 20 +++++++++++++-------
1 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/gdm72xx/gdm_usb.c b/drivers/staging/gdm72xx/gdm_usb.c
index 1e9dc0d..a5313fc 100644
--- a/drivers/staging/gdm72xx/gdm_usb.c
+++ b/drivers/staging/gdm72xx/gdm_usb.c
@@ -270,20 +270,17 @@ static void release_usb(struct usbwm_dev *udev)
}
}

-static void gdm_usb_send_complete(struct urb *urb)
+static void __gdm_usb_send_complete(struct urb *urb)
{
struct usb_tx *t = urb->context;
struct tx_cxt *tx = t->tx_cxt;
u8 *pkt = t->buf;
u16 cmd_evt;
- unsigned long flags;

/* Completion by usb_unlink_urb */
if (urb->status == -ECONNRESET)
return;

- spin_lock_irqsave(&tx->lock, flags);
-
if (t->callback)
t->callback(t->cb_data);

@@ -295,7 +292,16 @@ static void gdm_usb_send_complete(struct urb *urb)
put_tx_struct(tx, t);
else
free_tx_struct(t);
+}
+
+static void gdm_usb_send_complete(struct urb *urb)
+{
+ struct usb_tx *t = urb->context;
+ struct tx_cxt *tx = t->tx_cxt;
+ unsigned long flags;

+ spin_lock_irqsave(&tx->lock, flags);
+ __gdm_usb_send_complete(urb);
spin_unlock_irqrestore(&tx->lock, flags);
}

@@ -411,7 +417,7 @@ out:

send_fail:
t->callback = NULL;
- gdm_usb_send_complete(t->urb);
+ __gdm_usb_send_complete(t->urb);
spin_unlock_irqrestore(&tx->lock, flags);
return ret;
}
@@ -540,7 +546,7 @@ static void do_pm_control(struct work_struct *work)

if (ret) {
t->callback = NULL;
- gdm_usb_send_complete(t->urb);
+ __gdm_usb_send_complete(t->urb);
}
}
}
@@ -742,7 +748,7 @@ static int k_mode_thread(void *arg)

if (ret) {
t->callback = NULL;
- gdm_usb_send_complete(t->urb);
+ __gdm_usb_send_complete(t->urb);
}
}

--
1.7.7.3

2012-06-12 18:07:43

by Greg Kroah-Hartman

Subject: Re: [PATCH v2] staging: gdm72xx: Fix spinlock recursion on gdm_usb_send_complete

On Tue, Jun 12, 2012 at 10:40:52AM -0700, Ben Chan wrote:
> This patch fixes a spinlock recursion bug on several call sites of
> gdm_usb_send_complete by not calling spin_lock_irqsave on
> urb->context->tx_cxt->lock when the lock has already been acquired.
>
> Signed-off-by: Ben Chan <[email protected]>
> Cc: Sage Ahn <[email protected]>
> ---
> This revised patch simplifies the previous patch.

Argh, I _just_ applied the previous patch :(

Care to send me an incremental one, fixing it up to look like this now
so I don't have to revert your previous one?

thanks,

greg k-h