[PATCH 5/8] netpoll: add retry timeout

Matt Mackall
2005-08-12T02:20:13Z

Add limited retry logic to netpoll_send_skb

Each time we attempt to send, decrement our per-device retry counter.
On every successful send, we reset the counter.

We delay 50us between attempts with up to 20000 retries for a total of
1 second. After we've exhausted our retries, subsequent failed
attempts will try only once until reset by success.

Signed-off-by: Matt Mackall <mpm@selenic.com>

Index: lhg/net/core/netpoll.c
===================================================================
--- lhg.orig/net/core/netpoll.c 2005-08-11 16:17:45.000000000 -0700
+++ lhg/net/core/netpoll.c 2005-08-11 16:45:20.000000000 -0700
@@ -33,6 +33,7 @@
#define MAX_UDP_CHUNK 1460
#define MAX_SKBS 32
#define MAX_QUEUE_DEPTH (MAX_SKBS / 2)
+#define MAX_RETRIES 20000

static DEFINE_SPINLOCK(skb_list_lock);
static int nr_skbs;
@@ -265,7 +266,8 @@ static void netpoll_send_skb(struct netp
return;
}

- while (1) {
+ do {
+ npinfo->tries--;
spin_lock(&np->dev->xmit_lock);
np->dev->xmit_lock_owner = smp_processor_id();

@@ -277,6 +279,7 @@ static void netpoll_send_skb(struct netp
np->dev->xmit_lock_owner = -1;
spin_unlock(&np->dev->xmit_lock);
netpoll_poll(np);
+ udelay(50);
continue;
}

@@ -285,12 +288,15 @@ static void netpoll_send_skb(struct netp
spin_unlock(&np->dev->xmit_lock);

/* success */
- if(!status)
+ if(!status) {
+ npinfo->tries = MAX_RETRIES; /* reset */
return;
+ }

/* transmit busy */
netpoll_poll(np);
- }
+ udelay(50);
+ } while (npinfo->tries > 0);
}

void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
@@ -642,6 +648,7 @@ int netpoll_setup(struct netpoll *np)
npinfo->rx_np = NULL;
npinfo->poll_lock = SPIN_LOCK_UNLOCKED;
npinfo->poll_owner = -1;
+ npinfo->tries = MAX_RETRIES;
npinfo->rx_lock = SPIN_LOCK_UNLOCKED;
} else
npinfo = ndev->npinfo;
Index: lhg/include/linux/netpoll.h
===================================================================
--- lhg.orig/include/linux/netpoll.h 2005-08-11 15:40:27.000000000 -0700
+++ lhg/include/linux/netpoll.h 2005-08-11 16:17:56.000000000 -0700
@@ -26,6 +26,7 @@ struct netpoll {
struct netpoll_info {
spinlock_t poll_lock;
int poll_owner;
+ int tries;
int rx_flags;
spinlock_t rx_lock;
struct netpoll *rx_np; /* netpoll that registered an rx_hook */