On Fri, Feb 9, 2018 at 3:27 AM, Dean Nelson <dnel...@redhat.com> wrote: > On 02/08/2018 02:34 PM, David Miller wrote: >> >> From: Dean Nelson <dnel...@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 <dnel...@redhat.com> >> >> >> Applied, thanks. > > > Thank you! > >> >> Another way to solve this could have been to encode that length >> as "length - 1" > > > True. I had pondered that, but felt that since changing q_len's type > didn't add any length to the structure and that it was less impactful > from a number-of-lines of code changed perspective, I'd opt for this > route. > > Cavium, if you'd prefer this goes the route that Dave just mentioned, > please let me know and I can make a new patch against what's been > applied?
Thanks for fixing this and i think the current patch is fine. Thanks, Sunil. > > Thanks, > Dean > > > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-ker...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
