Messages in this thread |  | | Date | Mon, 30 Nov 2020 14:17:48 +0100 | From | Steen Hegelund <> | Subject | Re: [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver |
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On 28.11.2020 19:45, Andrew Lunn wrote: >EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > >> +/* Add a potentially wrapping 32 bit value to a 64 bit counter */ >> +static inline void sparx5_update_counter(u64 *cnt, u32 val) >> +{ >> + if (val < (*cnt & U32_MAX)) >> + *cnt += (u64)1 << 32; /* value has wrapped */ >> + >> + *cnt = (*cnt & ~(u64)U32_MAX) + val; >> +} > >I don't follow what this is doing. Could you give some examples?
The statistics counters comes from different sources, and unfortunately have different layouts: Some are 32 bit and some a 40 bit, so this function is a wrapper to be able to handle them in the same way, polling the counters often enough to be able to catch overruns.
> >> +static const char *const sparx5_stats_layout[] = { >> + "rx_in_bytes", >> + "rx_symbol_err", >> + "rx_pause", >> + "rx_unsup_opcode", > >> +static void sparx5_update_port_stats(struct sparx5 *sparx5, int portno) >> +{ >> + struct sparx5_port *spx5_port = sparx5->ports[portno]; >> + bool high_speed_dev = sparx5_is_high_speed_device(&spx5_port->conf); > >Reverse christmas tree. Which in this case, means you need to move the >assignment into the body of the code.
OK. > >> +static void sparx5_get_sset_strings(struct net_device *ndev, u32 sset, u8 *data) >> +{ >> + struct sparx5_port *port = netdev_priv(ndev); >> + struct sparx5 *sparx5 = port->sparx5; >> + int idx; >> + >> + if (sset != ETH_SS_STATS) >> + return; >> + >> + for (idx = 0; idx < sparx5->num_stats; idx++) >> + memcpy(data + idx * ETH_GSTRING_LEN, >> + sparx5->stats_layout[idx], ETH_GSTRING_LEN); > >You cannot use memcpy here, because the strings you have defined are >not ETH_GSTRING_LEN long. We once had a driver which happened to have >its strings at the end of a page. The memcpy would copy the string, >but keep going passed the end of string, over the page boundary, and >trigger a segmentation fault.
Yes, I see that.
Thanks for the comments /Steen > > Andrew
BR Steen
--------------------------------------- Steen Hegelund steen.hegelund@microchip.com
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