[Intel-wired-lan] [PATCH] ixgbe: Check whether FDIRCMD writes actually complete

[Alexander Duyck <alexander.duyck@gmail.com>]

On 06/10/2015 10:00 AM, Mark D Rustad wrote:
> Wait up to about 100 us for FDIRCMD writes to complete and return
> failure indications.
>
> Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>

Did you do any sort of performance testing with this patch applied? 
Specifically I would want to see the output of a TCP_RR and TCP_CRR test 
with this before and after.

The key reason being that adding signature filters is a part of the Tx 
hotpath when ATR is enabled, and if you are adding a spin wait to the Tx 
hotpath than you have killed performance.

> ---
>   drivers/net/ethernet/intel/ixgbe/ixgbe_82599.c |   74 ++++++++++++++++--------
>   drivers/net/ethernet/intel/ixgbe/ixgbe_type.h  |    1
>   2 files changed, 49 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_82599.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_82599.c
> index b1e364d26aa7..d0b309f0309e 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_82599.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_82599.c
> @@ -1,7 +1,7 @@
>   /*******************************************************************************
>   
>     Intel 10 Gigabit PCI Express Linux driver
> -  Copyright(c) 1999 - 2014 Intel Corporation.
> +  Copyright(c) 1999 - 2015 Intel Corporation.
>   
>     This program is free software; you can redistribute it and/or modify it
>     under the terms and conditions of the GNU General Public License,
> @@ -1246,6 +1246,25 @@ mac_reset_top:
>   }
>   
>   /**
> + * ixgbe_fdir_check_cmd_complete - poll to check whether FDIRCMD is complete
> + * @hw: pointer to hardware structure
> + * @fdircmd: current value of FDIRCMD register
> + */
> +static s32 ixgbe_fdir_check_cmd_complete(struct ixgbe_hw *hw, u32 *fdircmd)
> +{
> +	int i;
> +
> +	for (i = 0; i < IXGBE_FDIRCMD_CMD_POLL; i++) {
> +		*fdircmd = IXGBE_READ_REG(hw, IXGBE_FDIRCMD);
> +		if (!(*fdircmd & IXGBE_FDIRCMD_CMD_MASK))
> +			return 0;
> +		udelay(10);
> +	}
> +
> +	return IXGBE_ERR_FDIR_CMD_INCOMPLETE;
> +}
> +
> +/**
>    *  ixgbe_reinit_fdir_tables_82599 - Reinitialize Flow Director tables.
>    *  @hw: pointer to hardware structure
>    **/
> @@ -1253,6 +1272,8 @@ s32 ixgbe_reinit_fdir_tables_82599(struct ixgbe_hw *hw)
>   {
>   	int i;
>   	u32 fdirctrl = IXGBE_READ_REG(hw, IXGBE_FDIRCTRL);
> +	u32 fdircmd;
> +	s32 err;
>   
>   	fdirctrl &= ~IXGBE_FDIRCTRL_INIT_DONE;
>   
> @@ -1260,15 +1281,10 @@ s32 ixgbe_reinit_fdir_tables_82599(struct ixgbe_hw *hw)
>   	 * Before starting reinitialization process,
>   	 * FDIRCMD.CMD must be zero.
>   	 */
> -	for (i = 0; i < IXGBE_FDIRCMD_CMD_POLL; i++) {
> -		if (!(IXGBE_READ_REG(hw, IXGBE_FDIRCMD) &
> -		      IXGBE_FDIRCMD_CMD_MASK))
> -			break;
> -		udelay(10);
> -	}
> -	if (i >= IXGBE_FDIRCMD_CMD_POLL) {
> -		hw_dbg(hw, "Flow Director previous command isn't complete, aborting table re-initialization.\n");
> -		return IXGBE_ERR_FDIR_REINIT_FAILED;
> +	err = ixgbe_fdir_check_cmd_complete(hw, &fdircmd);
> +	if (err) {
> +		hw_dbg(hw, "Flow Director previous command did not complete, aborting table re-initialization.\n");
> +		return err;
>   	}
>   
>   	IXGBE_WRITE_REG(hw, IXGBE_FDIRFREE, 0);
> @@ -1513,8 +1529,9 @@ s32 ixgbe_fdir_add_signature_filter_82599(struct ixgbe_hw *hw,
>   					  union ixgbe_atr_hash_dword common,
>   					  u8 queue)
>   {
> -	u64  fdirhashcmd;
> -	u32  fdircmd;
> +	u64 fdirhashcmd;
> +	u32 fdircmd;
> +	s32 err;
>   
>   	/*
>   	 * Get the flow_type in order to program FDIRCMD properly
> @@ -1547,6 +1564,12 @@ s32 ixgbe_fdir_add_signature_filter_82599(struct ixgbe_hw *hw,
>   	fdirhashcmd |= ixgbe_atr_compute_sig_hash_82599(input, common);
>   	IXGBE_WRITE_REG64(hw, IXGBE_FDIRHASH, fdirhashcmd);
>   
> +	err = ixgbe_fdir_check_cmd_complete(hw, &fdircmd);
> +	if (err) {
> +		hw_dbg(hw, "Flow Director command did not complete!\n");
> +		return err;
> +	}
> +
>   	hw_dbg(hw, "Tx Queue=%x hash=%x\n", queue, (u32)fdirhashcmd);
>   
>   	return 0;

If a signature filter fails you should not block.  You should just 
continue.  There should be an interrupt that is triggered if the table 
is full and that is the only exception handling you should really have 
in this path.

> @@ -1758,6 +1781,7 @@ s32 ixgbe_fdir_write_perfect_filter_82599(struct ixgbe_hw *hw,
>   					  u16 soft_id, u8 queue)
>   {
>   	u32 fdirport, fdirvlan, fdirhash, fdircmd;
> +	s32 err;
>   
>   	/* currently IPv6 is not supported, must be programmed with 0 */
>   	IXGBE_WRITE_REG_BE32(hw, IXGBE_FDIRSIPv6(0),
> @@ -1806,6 +1830,11 @@ s32 ixgbe_fdir_write_perfect_filter_82599(struct ixgbe_hw *hw,
>   	fdircmd |= (u32)input->formatted.vm_pool << IXGBE_FDIRCMD_VT_POOL_SHIFT;
>   
>   	IXGBE_WRITE_REG(hw, IXGBE_FDIRCMD, fdircmd);
> +	err = ixgbe_fdir_check_cmd_complete(hw, &fdircmd);
> +	if (err) {
> +		hw_dbg(hw, "Flow Director command did not complete!\n");
> +		return err;
> +	}
>   
>   	return 0;
>   }
> @@ -1815,9 +1844,8 @@ s32 ixgbe_fdir_erase_perfect_filter_82599(struct ixgbe_hw *hw,
>   					  u16 soft_id)
>   {
>   	u32 fdirhash;
> -	u32 fdircmd = 0;
> -	u32 retry_count;
> -	s32 err = 0;
> +	u32 fdircmd;
> +	s32 err;
>   
>   	/* configure FDIRHASH register */
>   	fdirhash = input->formatted.bkt_hash;
> @@ -1830,18 +1858,12 @@ s32 ixgbe_fdir_erase_perfect_filter_82599(struct ixgbe_hw *hw,
>   	/* Query if filter is present */
>   	IXGBE_WRITE_REG(hw, IXGBE_FDIRCMD, IXGBE_FDIRCMD_CMD_QUERY_REM_FILT);
>   
> -	for (retry_count = 10; retry_count; retry_count--) {
> -		/* allow 10us for query to process */
> -		udelay(10);
> -		/* verify query completed successfully */
> -		fdircmd = IXGBE_READ_REG(hw, IXGBE_FDIRCMD);
> -		if (!(fdircmd & IXGBE_FDIRCMD_CMD_MASK))
> -			break;
> +	err = ixgbe_fdir_check_cmd_complete(hw, &fdircmd);
> +	if (err) {
> +		hw_dbg(hw, "Flow Director command did not complete!\n");
> +		return err;
>   	}
>   
> -	if (!retry_count)
> -		err = IXGBE_ERR_FDIR_REINIT_FAILED;
> -
>   	/* if filter exists in hardware then remove it */
>   	if (fdircmd & IXGBE_FDIRCMD_FILTER_VALID) {
>   		IXGBE_WRITE_REG(hw, IXGBE_FDIRHASH, fdirhash);
> @@ -1850,7 +1872,7 @@ s32 ixgbe_fdir_erase_perfect_filter_82599(struct ixgbe_hw *hw,
>   				IXGBE_FDIRCMD_CMD_REMOVE_FLOW);
>   	}
>   
> -	return err;
> +	return 0;
>   }
>   
>   /**
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
> index b6f424f3b1a8..b16d26b8f505 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
> @@ -3460,6 +3460,7 @@ struct ixgbe_info {
>   #define IXGBE_ERR_PBA_SECTION                   -31
>   #define IXGBE_ERR_INVALID_ARGUMENT              -32
>   #define IXGBE_ERR_HOST_INTERFACE_COMMAND        -33
> +#define IXGBE_ERR_FDIR_CMD_INCOMPLETE		-38
>   #define IXGBE_NOT_IMPLEMENTED                   0x7FFFFFFF
>   
>   #define IXGBE_KRM_PORT_CAR_GEN_CTRL(P)	((P == 0) ? (0x4010) : (0x8010))
>

Do you really need a new error return value?  Why not just rename 
IXGBE_ERR_FDIR_REINIT_FAILED since that is essentially what you are 
replacing with this new error value anyway.