Well, it's not quite that simple....
The order of events:
1. stored sk_buff data is modified in a reversible fashion (i.e. modified data is saved and restored after transmission).
2. sk_buff is queued for transmission
3. control returns back to interrupt handler. (yeah, this is all in soft_irq context, so I need it to be fast)
4. modified sk_buff data is restored, without knowing if the buffer has left the transmit queue and actually been put on the link.
So, there's a chance that: the modified data will get restored into the buffer before the actually transmission actually takes place.
Or is there? That's what I was sure about.
Does that make sense?
At 02:35 PM 1/27/2005, Gaurav Dhiman wrote:
--- Michael Hines <mhines@xxxxxxxxxx> wrote:
> I'm writing some code that intercepts and stores > socket buffers....lots of > them - and keeps them in memory for storage. (for > various reasons) > What I do is: when sk_buffs come in (the ones I > want), I isolate them, > unlink them, and orphan them and put them on a > linked list of my own.
> > Is there another mechanism to know for sure that an > sk_buff has been > transmitted? >
As you said you are saving the sk_buff on your own linked list, why dont you maintain the list of expanded element rather than sk_buff. Each extended element can have one element which will be a pointer to the actual sk_buff and another element of extended element can be a flag which can till you if the sk_buff data has been transmitted ot not. So each element of you linked list can be of following type:
struct ext_buffer{ sk_buff * net_data; int flag; struct ext_buffer *next_node; }
once you transmit the net_data, do set the flag, so that you can come to know next time that this data has already been dispatched.
I hope i understood your prob properly.
cheers!! --gd
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