[PATCH net-next 2/3] sunvnet: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN
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DORMANTno replies
REVIEWED: 1 (0M)
From: Sowmini Varadhan <hidden>
Date: 2014-08-12 14:33:15
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Status: Reviewed.
1 review trailer.
ldc_rx -> vnet_rx -> .. -> vnet_walk_rx->vnet_send_ack should not spin into an infinite loop waiting EAGAIN to lift. The sender could have sent us a burst, and gone to lunch without doing any more ldc_read()'s. That should not cause the receiver to loop infinitely till soft-lockup kicks in. Similarly __vnet_tx_trigger should only loop on EAGAIN a finite number of times. The caller (vnet_start_xmit()) already has code to reset the dring state and bail on errors from __vnet_tx_trigger Signed-off-by: Sowmini Varadhan <redacted> Acked-by: Raghuram Kothakota <redacted> --- drivers/net/ethernet/sun/sunvnet.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index b489dd0..39c39bf 100644
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c@@ -32,6 +32,11 @@ MODULE_DESCRIPTION("Sun LDOM virtual network driver"); MODULE_LICENSE("GPL"); MODULE_VERSION(DRV_MODULE_VERSION); +/* Heuristic for the number of times to exponentially backoff and + * retry sending an LDC trigger when EAGAIN is encountered + */ +#define VNET_MAX_RETRIES 10 + /* Ordered from largest major to lowest */ static struct vio_version vnet_versions[] = { { .major = 1, .minor = 0 },
@@ -260,6 +265,7 @@ static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr, .state = vio_dring_state, }; int err, delay; + int retries = 0; hdr.seq = dr->snd_nxt; delay = 1;
@@ -272,6 +278,13 @@ static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr, udelay(delay); if ((delay <<= 1) > 128) delay = 128; + if (retries++ > VNET_MAX_RETRIES) { + pr_info("ECONNRESET %x:%x:%x:%x:%x:%x\n", + port->raddr[0], port->raddr[1], + port->raddr[2], port->raddr[3], + port->raddr[4], port->raddr[5]); + err = -ECONNRESET; + } } while (err == -EAGAIN); return err;
@@ -593,6 +607,7 @@ static int __vnet_tx_trigger(struct vnet_port *port) .end_idx = (u32) -1, }; int err, delay; + int retries = 0; hdr.seq = dr->snd_nxt; delay = 1;
@@ -605,6 +620,8 @@ static int __vnet_tx_trigger(struct vnet_port *port) udelay(delay); if ((delay <<= 1) > 128) delay = 128; + if (retries++ > VNET_MAX_RETRIES) + break; } while (err == -EAGAIN); return err;
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1.8.4.2