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Message-ID: <1371543058.3252.214.camel@edumazet-glaptop>
Date: Tue, 18 Jun 2013 01:10:58 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: Dmitry Kravkov <dmitry@...adcom.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, eilong@...adcom.com
Subject: Re: [PATCH net-next 1/2] bnx2x: add support for ndo_ll_poll
On Tue, 2013-06-18 at 10:42 +0300, Dmitry Kravkov wrote:
> Adds ndo_ll_poll method and locking for FPs between LL and the napi.
>
> When receiving a packet we use skb_mark_ll to record the napi it came from.
> Add each napi to the napi_hash right after netif_napi_add().
>
> Signed-off-by: Dmitry Kravkov <dmitry@...adcom.com>
> Signed-off-by: Eilon Greenstein <eilong@...adcom.com>
> ---
> drivers/net/ethernet/broadcom/bnx2x/bnx2x.h | 125 +++++++++++++++++++++++
> drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 73 +++++++++++--
> drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h | 23 ++++-
> drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c | 4 +
> 4 files changed, 213 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
> index f76597e..a295a53 100644
> --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
> +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
> @@ -485,6 +485,21 @@ struct bnx2x_fastpath {
> struct bnx2x *bp; /* parent */
>
> struct napi_struct napi;
> +
> +#ifdef CONFIG_NET_LL_RX_POLL
> + unsigned int state;
> +#define BNX2X_FP_STATE_IDLE 0
> +#define BNX2X_FP_STATE_NAPI (1 << 0) /* NAPI owns this FP */
> +#define BNX2X_FP_STATE_POLL (1 << 1) /* poll owns this FP */
> +#define BNX2X_FP_STATE_NAPI_YIELD (1 << 2) /* NAPI yielded this FP */
> +#define BNX2X_FP_STATE_POLL_YIELD (1 << 3) /* poll yielded this FP */
> +#define BNX2X_FP_YIELD (BNX2X_FP_STATE_NAPI_YIELD | BNX2X_FP_STATE_POLL_YIELD)
> +#define BNX2X_FP_LOCKED (BNX2X_FP_STATE_NAPI | BNX2X_FP_STATE_POLL)
> +#define BNX2X_FP_USER_PEND (BNX2X_FP_STATE_POLL | BNX2X_FP_STATE_POLL_YIELD)
> + /* protect state */
> + spinlock_t lock;
> +#endif /* CONFIG_NET_LL_RX_POLL */
> +
> union host_hc_status_block status_blk;
> /* chip independent shortcuts into sb structure */
> __le16 *sb_index_values;
> @@ -557,6 +572,116 @@ struct bnx2x_fastpath {
> #define bnx2x_fp_stats(bp, fp) (&((bp)->fp_stats[(fp)->index]))
> #define bnx2x_fp_qstats(bp, fp) (&((bp)->fp_stats[(fp)->index].eth_q_stats))
>
> +#ifdef CONFIG_NET_LL_RX_POLL
> +static inline void bnx2x_fp_init_lock(struct bnx2x_fastpath *fp)
> +{
> + spin_lock_init(&fp->lock);
> + fp->state = BNX2X_FP_STATE_IDLE;
> +}
> +
> +/* called from the device poll routine to get ownership of a FP */
> +static inline int bnx2x_fp_lock_napi(struct bnx2x_fastpath *fp)
static inline bool ?
> +{
> + int rc = true;
> +
> + spin_lock(&fp->lock);
> + if (fp->state & BNX2X_FP_LOCKED) {
> + WARN_ON(fp->state & BNX2X_FP_STATE_NAPI);
> + fp->state |= BNX2X_FP_STATE_NAPI_YIELD;
> + rc = false;
> + } else {
> + /* we don't care if someone yielded */
> + fp->state = BNX2X_FP_STATE_NAPI;
> + }
> + spin_unlock(&fp->lock);
> + return rc;
> +}
> +
> +/* returns true is someone tried to get the FP while napi had it */
> +static inline int bnx2x_fp_unlock_napi(struct bnx2x_fastpath *fp)
bool
> +{
> + int rc = false;
> +
> + spin_lock(&fp->lock);
> + WARN_ON(fp->state &
> + (BNX2X_FP_STATE_POLL | BNX2X_FP_STATE_NAPI_YIELD));
> +
> + if (fp->state & BNX2X_FP_STATE_POLL_YIELD)
> + rc = true;
> + fp->state = BNX2X_FP_STATE_IDLE;
> + spin_unlock(&fp->lock);
> + return rc;
> +}
> +
> +/* called from bnx2x_low_latency_poll() */
> +static inline int bnx2x_fp_lock_poll(struct bnx2x_fastpath *fp)
bool
> +{
> + int rc = true;
> +
> + spin_lock_bh(&fp->lock);
> + if ((fp->state & BNX2X_FP_LOCKED)) {
> + fp->state |= BNX2X_FP_STATE_POLL_YIELD;
> + rc = false;
> + } else {
> + /* preserve yield marks */
> + fp->state |= BNX2X_FP_STATE_POLL;
> + }
> + spin_unlock_bh(&fp->lock);
> + return rc;
> +}
> +
> +/* returns true if someone tried to get the FP while it was locked */
> +static inline int bnx2x_fp_unlock_poll(struct bnx2x_fastpath *fp)
bool
> +{
> + int rc = false;
> +
> + spin_lock_bh(&fp->lock);
> + WARN_ON(fp->state & BNX2X_FP_STATE_NAPI);
> +
> + if (fp->state & BNX2X_FP_STATE_POLL_YIELD)
> + rc = true;
> + fp->state = BNX2X_FP_STATE_IDLE;
> + spin_unlock_bh(&fp->lock);
> + return rc;
> +}
> +
> +/* true if a socket is polling, even if it did not get the lock */
> +static inline int bnx2x_fp_ll_polling(struct bnx2x_fastpath *fp)
bool
> +{
> + WARN_ON(!(fp->state & BNX2X_FP_LOCKED));
> + return fp->state & BNX2X_FP_USER_PEND;
> +}
> +#else
> +static inline void bnx2x_fp_init_lock(struct bnx2x_fastpath *fp)
> +{
> +}
> +
> +static inline bool bnx2x_fp_lock_napi(struct bnx2x_fastpath *fp)
> +{
> + return true;
> +}
> +
> +static inline bool bnx2x_fp_unlock_napi(struct bnx2x_fastpath *fp)
> +{
> + return false;
> +}
> +
> +static inline bool bnx2x_fp_lock_poll(struct bnx2x_fastpath *fp)
> +{
> + return false;
> +}
> +
> +static inline bool bnx2x_fp_unlock_poll(struct bnx2x_fastpath *fp)
> +{
> + return false;
> +}
> +
> +static inline bool bnx2x_fp_ll_polling(struct bnx2x_fastpath *fp)
> +{
> + return false;
> +}
> +#endif /* CONFIG_NET_LL_RX_POLL */
> +
> /* Use 2500 as a mini-jumbo MTU for FCoE */
> #define BNX2X_FCOE_MINI_JUMBO_MTU 2500
>
> diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
> index 4e42bdd..d8d371b 100644
> --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
> +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
> @@ -24,6 +24,7 @@
> #include <net/tcp.h>
> #include <net/ipv6.h>
> #include <net/ip6_checksum.h>
> +#include <net/ll_poll.h>
> #include <linux/prefetch.h>
> #include "bnx2x_cmn.h"
> #include "bnx2x_init.h"
> @@ -669,7 +670,12 @@ static void bnx2x_gro_receive(struct bnx2x *bp, struct bnx2x_fastpath *fp,
> }
> }
> #endif
> - napi_gro_receive(&fp->napi, skb);
> + skb_mark_ll(skb, &fp->napi);
> +
> + if (bnx2x_fp_ll_polling(fp))
> + netif_receive_skb(skb);
> + else
> + napi_gro_receive(&fp->napi, skb);
> }
>
This is racy [1], so I would not care and always call napi_gro_receive()
[1] We would have to flush GRO state every time we call
bnx2x_fp_lock_poll()
Ideally, we could keep a counter of enabled LLS sockets, to
automatically switch off/on GRO, but in net/core, not in every driver.
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