The old code did not check the return value of skb_clone(). The extra skb_clone() is not needed at all, if using skb_realloc_headroom() instead, which gives us a private copy with enough headroom as well. We need to requeue the original skb if the call failed, because we cannot inform upper layers about the data loss. Restructure the code to minimise rollback effort if it happens. This fix kernel bug #86091
Thanks to Insu Yun <[email protected]> to remind me on this issue. Signed-off-by: Karsten Keil <[email protected]> --- drivers/isdn/mISDN/layer2.c | 54 +++++++++++++++++---------------------------- 1 file changed, 20 insertions(+), 34 deletions(-) diff --git a/drivers/isdn/mISDN/layer2.c b/drivers/isdn/mISDN/layer2.c index 949cabb..5eb380a 100644 --- a/drivers/isdn/mISDN/layer2.c +++ b/drivers/isdn/mISDN/layer2.c @@ -1476,7 +1476,7 @@ static void l2_pull_iqueue(struct FsmInst *fi, int event, void *arg) { struct layer2 *l2 = fi->userdata; - struct sk_buff *skb, *nskb, *oskb; + struct sk_buff *skb, *nskb; u_char header[MAX_L2HEADER_LEN]; u_int i, p1; @@ -1486,48 +1486,34 @@ l2_pull_iqueue(struct FsmInst *fi, int event, void *arg) skb = skb_dequeue(&l2->i_queue); if (!skb) return; - - if (test_bit(FLG_MOD128, &l2->flag)) - p1 = (l2->vs - l2->va) % 128; - else - p1 = (l2->vs - l2->va) % 8; - p1 = (p1 + l2->sow) % l2->window; - if (l2->windowar[p1]) { - printk(KERN_WARNING "%s: l2 try overwrite ack queue entry %d\n", - mISDNDevName4ch(&l2->ch), p1); - dev_kfree_skb(l2->windowar[p1]); - } - l2->windowar[p1] = skb; i = sethdraddr(l2, header, CMD); if (test_bit(FLG_MOD128, &l2->flag)) { header[i++] = l2->vs << 1; header[i++] = l2->vr << 1; + } else + header[i++] = (l2->vr << 5) | (l2->vs << 1); + nskb = skb_realloc_headroom(skb, i); + if (!nskb) { + printk(KERN_WARNING "%s: no headroom(%d) copy for IFrame\n", + mISDNDevName4ch(&l2->ch), i); + skb_queue_head(&l2->i_queue, skb); + return; + } + if (test_bit(FLG_MOD128, &l2->flag)) { + p1 = (l2->vs - l2->va) % 128; l2->vs = (l2->vs + 1) % 128; } else { - header[i++] = (l2->vr << 5) | (l2->vs << 1); + p1 = (l2->vs - l2->va) % 8; l2->vs = (l2->vs + 1) % 8; } - - nskb = skb_clone(skb, GFP_ATOMIC); - p1 = skb_headroom(nskb); - if (p1 >= i) - memcpy(skb_push(nskb, i), header, i); - else { - printk(KERN_WARNING - "%s: L2 pull_iqueue skb header(%d/%d) too short\n", - mISDNDevName4ch(&l2->ch), i, p1); - oskb = nskb; - nskb = mI_alloc_skb(oskb->len + i, GFP_ATOMIC); - if (!nskb) { - dev_kfree_skb(oskb); - printk(KERN_WARNING "%s: no skb mem in %s\n", - mISDNDevName4ch(&l2->ch), __func__); - return; - } - memcpy(skb_put(nskb, i), header, i); - memcpy(skb_put(nskb, oskb->len), oskb->data, oskb->len); - dev_kfree_skb(oskb); + p1 = (p1 + l2->sow) % l2->window; + if (l2->windowar[p1]) { + printk(KERN_WARNING "%s: l2 try overwrite ack queue entry %d\n", + mISDNDevName4ch(&l2->ch), p1); + dev_kfree_skb(l2->windowar[p1]); } + l2->windowar[p1] = skb; + memcpy(skb_push(nskb, i), header, i); l2down(l2, PH_DATA_REQ, l2_newid(l2), nskb); test_and_clear_bit(FLG_ACK_PEND, &l2->flag); if (!test_and_set_bit(FLG_T200_RUN, &l2->flag)) { -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
