4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit 2695578b896aea472b2c0dcbe9d92daa71738484 ]
Marek reported a LOCKDEP issue occurring on 32bit host, that we tracked down to the fact that usbnet could either run from soft or hard irqs.
This patch adds u64_stats_update_begin_irqsave() and u64_stats_update_end_irqrestore() helpers to solve this case.
[ 17.768040] ================================ [ 17.772239] WARNING: inconsistent lock state [ 17.776511] 4.16.0-rc3-next-20180227-00007-g876c53a7493c #453 Not tainted [ 17.783329] -------------------------------- [ 17.787580] inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. [ 17.793607] swapper/0/0 [HC0[0]:SC1[1]:HE1:SE0] takes: [ 17.798751] (&syncp->seq#5){?.-.}, at: [<9b22e5f0>] asix_rx_fixup_internal+0x188/0x288 [ 17.806790] {IN-HARDIRQ-W} state was registered at: [ 17.811677] tx_complete+0x100/0x208 [ 17.815319] __usb_hcd_giveback_urb+0x60/0xf0 [ 17.819770] xhci_giveback_urb_in_irq+0xa8/0x240 [ 17.824469] xhci_td_cleanup+0xf4/0x16c [ 17.828367] xhci_irq+0xe74/0x2240 [ 17.831827] usb_hcd_irq+0x24/0x38 [ 17.835343] __handle_irq_event_percpu+0x98/0x510 [ 17.840111] handle_irq_event_percpu+0x1c/0x58 [ 17.844623] handle_irq_event+0x38/0x5c [ 17.848519] handle_fasteoi_irq+0xa4/0x138 [ 17.852681] generic_handle_irq+0x18/0x28 [ 17.856760] __handle_domain_irq+0x6c/0xe4 [ 17.860941] gic_handle_irq+0x54/0xa0 [ 17.864666] __irq_svc+0x70/0xb0 [ 17.867964] arch_cpu_idle+0x20/0x3c [ 17.871578] arch_cpu_idle+0x20/0x3c [ 17.875190] do_idle+0x144/0x218 [ 17.878468] cpu_startup_entry+0x18/0x1c [ 17.882454] start_kernel+0x394/0x400 [ 17.886177] irq event stamp: 161912 [ 17.889616] hardirqs last enabled at (161912): [<7bedfacf>] __netdev_alloc_skb+0xcc/0x140 [ 17.897893] hardirqs last disabled at (161911): [<d58261d0>] __netdev_alloc_skb+0x94/0x140 [ 17.904903] exynos5-hsi2c 12ca0000.i2c: tx timeout [ 17.906116] softirqs last enabled at (161904): [<387102ff>] irq_enter+0x78/0x80 [ 17.906123] softirqs last disabled at (161905): [<cf4c628e>] irq_exit+0x134/0x158 [ 17.925722]. [ 17.925722] other info that might help us debug this: [ 17.933435] Possible unsafe locking scenario: [ 17.933435]. [ 17.940331] CPU0 [ 17.942488] ---- [ 17.944894] lock(&syncp->seq#5); [ 17.948274] <Interrupt> [ 17.950847] lock(&syncp->seq#5); [ 17.954386]. [ 17.954386] *** DEADLOCK *** [ 17.954386]. [ 17.962422] no locks held by swapper/0/0.
Fixes: c8b5d129ee29 ("net: usbnet: support 64bit stats") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: Marek Szyprowski m.szyprowski@samsung.com Cc: Greg Ungerer gerg@linux-m68k.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/usb/usbnet.c | 10 ++++++---- include/linux/u64_stats_sync.h | 22 ++++++++++++++++++++++ 2 files changed, 28 insertions(+), 4 deletions(-)
--- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -315,6 +315,7 @@ static void __usbnet_status_stop_force(s void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb) { struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->stats64); + unsigned long flags; int status;
if (test_bit(EVENT_RX_PAUSED, &dev->flags)) { @@ -326,10 +327,10 @@ void usbnet_skb_return (struct usbnet *d if (skb->protocol == 0) skb->protocol = eth_type_trans (skb, dev->net);
- u64_stats_update_begin(&stats64->syncp); + flags = u64_stats_update_begin_irqsave(&stats64->syncp); stats64->rx_packets++; stats64->rx_bytes += skb->len; - u64_stats_update_end(&stats64->syncp); + u64_stats_update_end_irqrestore(&stats64->syncp, flags);
netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n", skb->len + sizeof (struct ethhdr), skb->protocol); @@ -1250,11 +1251,12 @@ static void tx_complete (struct urb *urb
if (urb->status == 0) { struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->stats64); + unsigned long flags;
- u64_stats_update_begin(&stats64->syncp); + flags = u64_stats_update_begin_irqsave(&stats64->syncp); stats64->tx_packets += entry->packets; stats64->tx_bytes += entry->length; - u64_stats_update_end(&stats64->syncp); + u64_stats_update_end_irqrestore(&stats64->syncp, flags); } else { dev->net->stats.tx_errors++;
--- a/include/linux/u64_stats_sync.h +++ b/include/linux/u64_stats_sync.h @@ -90,6 +90,28 @@ static inline void u64_stats_update_end( #endif }
+static inline unsigned long +u64_stats_update_begin_irqsave(struct u64_stats_sync *syncp) +{ + unsigned long flags = 0; + +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + local_irq_save(flags); + write_seqcount_begin(&syncp->seq); +#endif + return flags; +} + +static inline void +u64_stats_update_end_irqrestore(struct u64_stats_sync *syncp, + unsigned long flags) +{ +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + write_seqcount_end(&syncp->seq); + local_irq_restore(flags); +#endif +} + static inline void u64_stats_update_begin_raw(struct u64_stats_sync *syncp) { #if BITS_PER_LONG==32 && defined(CONFIG_SMP)