Messages in this thread Patch in this message | | | Date | Wed, 28 Nov 2012 21:18:37 +0100 | From | Krzysztof Mazur <> | Subject | Re: [PATCH v2 3/3] pppoatm: protect against freeing of vcc |
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On Tue, Nov 27, 2012 at 07:28:43PM +0100, Krzysztof Mazur wrote: > > While reviewing your br2684 patch I also found that some ATM drivers does > not call ->pop() when ->send() fails, they should do: > > if (vcc->pop) > vcc->pop(vcc, skb); > else > dev_kfree_skb(skb); > > but some drivers just call dev_kfree_skb(skb). > > I think that we should add atm_pop() function that does that and fix all > drivers. >
I'm sending a patch that implements that idea.
Currently we need two arguments vcc and skb. However, we have reserved ATM_SKB(skb)->vcc in skb control block for keeping vcc and we can create single argument version vcc_pop(skb). In that case we need to move:
ATM_SKB(skb)->vcc = vcc;
from ATM drivers to functions that call atmdev_ops->send().
Krzysiek -- >8 -- Subject: [PATCH] atm: introduce vcc_pop_*()
The atm drivers to free skb, that they got from ->send(), cannot just use dev_kfree_skb*(), but they must use something like:
if (vcc->pop) vcc->pop(vcc, skb); else dev_kfree_skb_any(skb);
When vcc->pop is non-NULL, but they must in such case call vcc->pop(). This causes duplicated code in many drivers, and some drivers even forgot to call vcc->pop() in some error handling code.
The new vcc_pop_*() functions are equivalent to dev_kfree_skb*(). Currently we always use dev_kfree_skb_any() to free, because using other versions it's probably worthless optimization - in ->pop() we already use only dev_kfree_skb_any(). The other functions we added only to not loose information from converting existing code that uses some non-any dev_kfree_skb*() variants.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net> --- include/linux/atmdev.h | 11 +++++++++++ net/atm/common.c | 9 +++++++++ 2 files changed, 20 insertions(+)
diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h index c1da539..dedccad 100644 --- a/include/linux/atmdev.h +++ b/include/linux/atmdev.h @@ -283,6 +283,17 @@ int atm_pcr_goal(const struct atm_trafprm *tp); void vcc_release_async(struct atm_vcc *vcc, int reply); +/* + * vcc_pop_*() functions should be used by ATM driver to free transmitted + * skbs - skbs that were sent to driver by atmdev_opt->send() function. + * + * We provide three functions that can be used in different contexts. + * See dev_kfree_skb*() documentation for details. + */ +void vcc_pop_any(struct atm_vcc *vcc, struct sk_buff *skb); +#define vcc_pop(vcc, skb) vcc_pop_any(vcc, skb) +#define vcc_pop_irq(vcc, skb) vcc_pop_any(vcc, skb) + struct atm_ioctl { struct module *owner; /* A module reference is kept if appropriate over this call. diff --git a/net/atm/common.c b/net/atm/common.c index 806fc0a..ad9c77d 100644 --- a/net/atm/common.c +++ b/net/atm/common.c @@ -654,6 +654,15 @@ out: return error; } +void vcc_pop_any(struct atm_vcc *vcc, struct sk_buff *skb) +{ + if (vcc->pop) + vcc->pop(vcc, skb); + else + dev_kfree_skb_any(skb); +} +EXPORT_SYMBOL(vcc_pop_any); + unsigned int vcc_poll(struct file *file, struct socket *sock, poll_table *wait) { struct sock *sk = sock->sk; -- 1.8.0.411.g71a7da8
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