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Re: [PATCH] ipv4 skbuff locking scope

To: tleete@xxxxxxxxxxxx
Subject: Re: [PATCH] ipv4 skbuff locking scope
From: "David S. Miller" <davem@xxxxxxxxxx>
Date: Mon, 30 Oct 2000 20:03:24 -0800
Cc: linux-kernel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <39FE39EF.62CC880B@xxxxxxxxxxxx> (message from Tom Leete on Mon, 30 Oct 2000 22:18:07 -0500)
References: <39FDF518.A9F1204D@xxxxxxxxxxxx> <200010302224.OAA02266@xxxxxxxxxxxxxxx> <39FE39EF.62CC880B@xxxxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
   Date: Mon, 30 Oct 2000 22:18:07 -0500
   From: Tom Leete <tleete@xxxxxxxxxxxx>

   > Look, if the sleep condition test "races" due to not holding the
   > lock, the schedule() just returns because if the sleep condidion
   > test passes then by definition this means we were also woken up,
   > see?

   Would you explain what is accomplished by toggling the lock every
   time through? What breaks by not doing so?

Incoming packets are not processed while the lock is held, they
get queued to the backlog.  When the lock is released, the backlog
packets get processed.

For a TCP sender, these backlog packets are ACKs making room in the
send buffer so that the application can put more data into the send
buffer.

Later,
David S. Miller
davem@xxxxxxxxxx

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