crypto/NX: Set receive window credits to max number of CRBs in RxFIFO

[Michael Ellerman]

Haren Myneni <haren at linux.vnet.ibm.com> writes:
>     
> System gets checkstop if RxFIFO overruns with more requests than the
> maximum possible number of CRBs in FIFO at the same time. So find max
> CRBs from FIFO size and set it to receive window credits.
>    
> CC: stable at vger.kernel.org # v4.14+
> Signed-off-by:Haren Myneni <haren at us.ibm.com>

It's helpful to mention the actual commit that's fixed, so that people
with backports can join things up, so should that be:

  Fixes: b0d6c9bab5e4 ("crypto/nx: Add P9 NX support for 842 compression engine")

???

cheers

> diff --git a/drivers/crypto/nx/nx-842-powernv.c b/drivers/crypto/nx/nx-842-powernv.c
> index 4acbc47..e78ff5c 100644
> --- a/drivers/crypto/nx/nx-842-powernv.c
> +++ b/drivers/crypto/nx/nx-842-powernv.c
> @@ -27,8 +27,6 @@
>  #define WORKMEM_ALIGN	(CRB_ALIGN)
>  #define CSB_WAIT_MAX	(5000) /* ms */
>  #define VAS_RETRIES	(10)
> -/* # of requests allowed per RxFIFO at a time. 0 for unlimited */
> -#define MAX_CREDITS_PER_RXFIFO	(1024)
>  
>  struct nx842_workmem {
>  	/* Below fields must be properly aligned */
> @@ -812,7 +810,11 @@ static int __init vas_cfg_coproc_info(struct device_node *dn, int chip_id,
>  	rxattr.lnotify_lpid = lpid;
>  	rxattr.lnotify_pid = pid;
>  	rxattr.lnotify_tid = tid;
> -	rxattr.wcreds_max = MAX_CREDITS_PER_RXFIFO;
> +	/*
> +	 * Maximum RX window credits can not be more than #CRBs in
> +	 * RxFIFO. Otherwise, can get checkstop if RxFIFO overruns.
> +	 */
> +	rxattr.wcreds_max = fifo_size / CRB_SIZE;
>  
>  	/*
>  	 * Open a VAS receice window which is used to configure RxFIFO