Subject: [patch v3] Documentation: add a guideline for hard_start_xmit method

From: Matti Linnanvuori <[email-masked]>
Date: Tue, 15 Jan 2008 06:25:27 -0800 (PST)

From: Matti Linnanvuori <[email-masked]>

Add a guideline not to modify SKBs.

Signed-off-by: Matti Linnanvuori <[email-masked]>

---

--- a/Documentation/networking/driver.txt 2008-01-13 07:14:01.608291500 +0200
+++ b/Documentation/networking/driver.txt 2008-01-15 16:16:14.636054000 +0200
@@ -61,7 +61,10 @@ Transmit path guidelines:
 2) Do not forget to update netdev->trans_start to jiffies after
    each new tx packet is given to the hardware.
 
-3) Do not forget that once you return 0 from your hard_start_xmit
+3) A hard_start_xmit method must not modify the shared parts of a
+   cloned SKB.
+
+4) Do not forget that once you return 0 from your hard_start_xmit
    method, it is your driver's responsibility to free up the SKB
    and in some finite amount of time.

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