From 94191fd6718c6ae000afdad2ade5c473d1439c57 Mon Sep 17 00:00:00 2001 From: Nimrod Andy Date: Tue, 16 Dec 2014 18:25:58 +0800 Subject: [PATCH] net: fec: Fix NAPI race Do camera capture test on i.MX6q sabresd board, and save the capture data to nfs rootfs. The command is: gst-launch-1.0 -e imxv4l2src device=/dev/video1 num-buffers=2592000 ! tee name=t ! queue ! imxv4l2sink sync=false t. ! queue ! vpuenc ! queue ! mux. pulsesrc num-buffers=3720937 blocksize=4096 ! 'audio/x-raw, rate=44100, channels=2' ! queue ! imxmp3enc ! mpegaudioparse ! queue ! mux. qtmux name=mux ! filesink location=video_recording_long.mov After about 10 hours running, there have net watchdog timeout kernel dump: ... WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:264 dev_watchdog+0x2b4/0x2d8() NETDEV WATCHDOG: eth0 (fec): transmit queue 0 timed out CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.14.24-01051-gdb840b7 #440 [<80014e6c>] (unwind_backtrace) from [<800118ac>] (show_stack+0x10/0x14) [<800118ac>] (show_stack) from [<806ae3f0>] (dump_stack+0x78/0xc0) [<806ae3f0>] (dump_stack) from [<8002b504>] (warn_slowpath_common+0x68/0x8c) [<8002b504>] (warn_slowpath_common) from [<8002b558>] (warn_slowpath_fmt+0x30/0x40) [<8002b558>] (warn_slowpath_fmt) from [<8055e0d4>] (dev_watchdog+0x2b4/0x2d8) [<8055e0d4>] (dev_watchdog) from [<800352d8>] (call_timer_fn.isra.33+0x24/0x8c) [<800352d8>] (call_timer_fn.isra.33) from [<800354c4>] (run_timer_softirq+0x184/0x220) [<800354c4>] (run_timer_softirq) from [<8002f420>] (__do_softirq+0xc0/0x22c) [<8002f420>] (__do_softirq) from [<8002f804>] (irq_exit+0xa8/0xf4) [<8002f804>] (irq_exit) from [<8000ee5c>] (handle_IRQ+0x54/0xb4) [<8000ee5c>] (handle_IRQ) from [<80008598>] (gic_handle_irq+0x28/0x5c) [<80008598>] (gic_handle_irq) from [<800123c0>] (__irq_svc+0x40/0x74) Exception stack(0x80d27f18 to 0x80d27f60) 7f00: 80d27f60 0000014c 7f20: 8858c60e 0000004d 884e4540 0000004d ab7250d0 80d34348 00000000 00000000 7f40: 00000001 00000000 00000017 80d27f60 800702a4 80476e6c 600f0013 ffffffff [<800123c0>] (__irq_svc) from [<80476e6c>] (cpuidle_enter_state+0x50/0xe0) [<80476e6c>] (cpuidle_enter_state) from [<80476fa8>] (cpuidle_idle_call+0xac/0x154) [<80476fa8>] (cpuidle_idle_call) from [<8000f174>] (arch_cpu_idle+0x8/0x44) [<8000f174>] (arch_cpu_idle) from [<80064c54>] (cpu_startup_entry+0x100/0x158) [<80064c54>] (cpu_startup_entry) from [<80cd8a9c>] (start_kernel+0x304/0x368) ---[ end trace 09ebd32fb032f86d ]--- ... There might have a race in napi_schedule(), leaving interrupts disabled forever. After these patch, the case still work more than 40 hours running. Signed-off-by: Fugang Duan Signed-off-by: David S. Miller --- drivers/net/ethernet/freescale/fec_main.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index ebf76c496e7a..5ebdf8dc8a31 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -1558,20 +1558,21 @@ fec_enet_interrupt(int irq, void *dev_id) { struct net_device *ndev = dev_id; struct fec_enet_private *fep = netdev_priv(ndev); - const unsigned napi_mask = FEC_ENET_RXF | FEC_ENET_TXF; uint int_events; irqreturn_t ret = IRQ_NONE; int_events = readl(fep->hwp + FEC_IEVENT); - writel(int_events & ~napi_mask, fep->hwp + FEC_IEVENT); + writel(int_events, fep->hwp + FEC_IEVENT); fec_enet_collect_events(fep, int_events); - if (int_events & napi_mask) { + if (fep->work_tx || fep->work_rx) { ret = IRQ_HANDLED; - /* Disable the NAPI interrupts */ - writel(FEC_ENET_MII, fep->hwp + FEC_IMASK); - napi_schedule(&fep->napi); + if (napi_schedule_prep(&fep->napi)) { + /* Disable the NAPI interrupts */ + writel(FEC_ENET_MII, fep->hwp + FEC_IMASK); + __napi_schedule(&fep->napi); + } } if (int_events & FEC_ENET_MII) { @@ -1591,12 +1592,6 @@ static int fec_enet_rx_napi(struct napi_struct *napi, int budget) struct fec_enet_private *fep = netdev_priv(ndev); int pkts; - /* - * Clear any pending transmit or receive interrupts before - * processing the rings to avoid racing with the hardware. - */ - writel(FEC_ENET_RXF | FEC_ENET_TXF, fep->hwp + FEC_IEVENT); - pkts = fec_enet_rx(ndev, budget); fec_enet_tx(ndev); -- 2.30.2