[PATCH RESEND 2/5] kexec: Export kexec_in_progress

[wenxiong at linux.vnet.ibm.com]

Reviewed-by: Wen Xiong<wenxiong at linux.vnet.ibm.com>

Thanks,
Wendy

Quoting Brian King <brking at linux.vnet.ibm.com>:

> A kexec boot for some ipr SAS adapters was seen to take ~20 seconds
> just doing ipr adapter initialization. This is due to the fact that
> a kexec invokes the driver's shutdown handler which places the adapter
> into a state that requires a hard reset and resulting firmware initialization
> to be usable again, which takes significant time. By exporting  
> kexec_in_progress,
> this process can be optimized significantly in the driver by essentially
> placing the adapter into a state where this hardware reset and  
> re-initialization
> can be bypassed, eliminating this delay in kexec boot.
>
> Cc: Eric Biederman <ebiederm at xmission.com>
> Cc: kexec <kexec at lists.infradead.org>
> Signed-off-by: Brian King <brking at linux.vnet.ibm.com>
> ---
>
>  kernel/kexec.c |    2 ++
>  1 file changed, 2 insertions(+)
>
> diff -puN kernel/kexec.c~kexec_export_in_prog kernel/kexec.c
> --- scsi-queue/kernel/kexec.c~kexec_export_in_prog	2014-12-02  
> 12:13:22.820325731 -0600
> +++ scsi-queue-bjking1/kernel/kexec.c	2014-12-02 12:13:22.825325687 -0600
> @@ -2768,3 +2768,5 @@ int kernel_kexec(void)
>  	mutex_unlock(&kexec_mutex);
>  	return error;
>  }
> +
> +EXPORT_SYMBOL_GPL(kexec_in_progress);
> _