Messages in this thread | | | Date | Thu, 08 Feb 2018 15:34:53 -0500 (EST) | Subject | Re: net: thunder: change q_len's type to handle max ring size | From | David Miller <> |
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From: Dean Nelson <dnelson@redhat.com> Date:
> The Cavium thunder nicvf driver supports rx/tx rings of up to 65536 entries per. > The number of entires are stored in the q_len member of struct q_desc_mem. The > problem is that q_len being a u16, results in 65536 becoming 0. > > In getting pointers to descriptors in the rings, the driver uses q_len minus 1 > as a mask after incrementing the pointer, in order to go back to the beginning > and not go past the end of the ring. > > With the q_len set to 0 the mask is no longer correct and the driver does go > beyond the end of the ring, causing various ills. Usually the first thing that > shows up is a "NETDEV WATCHDOG: enP2p1s0f1 (nicvf): transmit queue 7 timed out" > warning. > > This patch remedies the problem by changing q_len to a u32. > > Signed-off-by: Dean Nelson <dnelson@redhat.com>
Applied, thanks.
Another way to solve this could have been to encode that length as "length - 1"
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