Felix Fietkau 96eb3d883d cns3xxx: ethernet - resolve SMP issue ... The combination of r35942 and r35952 causes an issue where eth_schedule_poll() can be called from a different CPU between the call to napi_complete() and the setting of cur_index which can break the rx ring accounting and cause ethernet latency and/or ethernet stalls. The issue can be easilly created by adding a couple of artificial delays such as: @@ -715,6 +715,7 @@ static int eth_poll(struct napi_struct *napi, int budget) if (!received) { napi_complete(napi); +udelay(1000); enable_irq(IRQ_CNS3XXX_SW_R0RXC); } @@ -727,6 +728,7 @@ static int eth_poll(struct napi_struct *napi, int budget) rx_ring->cur_index = i; wmb(); +udelay(1000); enable_rx_dma(sw); return received; This patch moves the setting of cur_index back up where it needs to be and addresses the original corner case that r35942 was trying to catch in an improved fashion by checking to see if the rx descriptor ring has become full before interrupts were re-enabled so that a poll can be scheduled again and avoid an rx stall caused by rx interrupts ceasing to fire again. Signed-off-by: Tim Harvey <tharvey@gateworks.com> SVN-Revision: 39761		2014-02-27 23:02:37 +00:00
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cns3xxx_eth.c	cns3xxx: ethernet - resolve SMP issue	2014-02-27 23:02:37 +00:00
Kconfig	cns3xxx: convert ethernet patches to files	2012-11-11 20:03:56 +00:00
Makefile	cns3xxx: convert ethernet patches to files	2012-11-11 20:03:56 +00:00