Re: [PATCH 8/8] [I/OAT] TCP recv offload to I/OAT

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Chris Leech <[email protected]> wrote:
>
> +#ifdef CONFIG_NET_DMA
>  +	tp->ucopy.dma_chan = NULL;
>  +	if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) && !sysctl_tcp_low_latency && __get_cpu_var(softnet_data.net_dma))
>  +		dma_lock_iovec_pages(msg->msg_iov, len, &tp->ucopy.locked_list);
>  +#endif

The __get_cpu_var() here will run smp_processor_id() from preemptible
context.  You'll get a big warning if the correct debug options are set.

The reason for this is that preemption could cause this code to hop between
CPUs.

Please always test code with all debug options enabled and with full kernel
preemption.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux