Re: [BUGFIX PATCH 2/2] brcmfmac: Change vif_event_lock to spinlock

From: Arend Van Spriel
Date: Mon Aug 15 2016 - 17:46:18 EST

On 15-8-2016 11:41, Masami Hiramatsu wrote:
> Change vif_event_lock to spinlock from mutex, since this lock is
> used in wait_event_timeout() via vif_event_equals(). This caused
> a warning report as below.
>
> As far as I can see, this lock protects regions where updating
> structure members, not function calls. Also, since those
> regions are not called from interrupt handlers (of course, it
> was a mutex), spin_lock is used instead of spin_lock_irqsave.
>
> [ 186.678550] ------------[ cut here ]------------
> [ 186.678556] WARNING: CPU: 2 PID: 7140 at /home/mhiramat/ksrc/linux/kernel/sched/core.c:7545 __might_sleep+0x7c/0x80
> [ 186.678560] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff980d9090>] prepare_to_wait_event+0x60/0x100
> [ 186.678560] Modules linked in: brcmfmac xt_CHECKSUM rfcomm ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_addrtype br_netfilter xt_tcpudp ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_raw ip6table_security ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_filter ip6_tables iptable_raw iptable_security iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_filter ip_tables x_tables bnep nls_iso8859_1 i2c_designware_platform i2c_designware_core snd_hda_codec_hdmi snd_hda_codec_realtek dcdbas snd_hda_codec_generic snd_hda_intel snd_hda_codec intel_rapl snd_hda_core x86_pkg_temp_thermal intel_powerclamp coretemp
> [ 186.678594] snd_pcm crct10dif_pclmul crc32_pclmul aesni_intel aes_x86_64 joydev glue_helper snd_hwdep lrw gf128mul uvcvideo ablk_helper snd_seq_midi cryptd snd_seq_midi_event snd_rawmidi videobuf2_vmalloc videobuf2_memops snd_seq input_leds videobuf2_v4l2 cfg80211 videobuf2_core snd_timer videodev serio_raw btusb snd_seq_device media btrtl rtsx_pci_ms snd mei_me memstick hid_multitouch mei soundcore brcmutil idma64 virt_dma intel_lpss_pci processor_thermal_device intel_soc_dts_iosf hci_uart btbcm btqca btintel bluetooth int3403_thermal dell_smo8800 intel_lpss_acpi intel_lpss int3402_thermal int340x_thermal_zone intel_hid mac_hid int3400_thermal shpchp sparse_keymap acpi_pad acpi_thermal_rel acpi_als kfifo_buf industrialio kvm_intel kvm irqbypass parport_pc ppdev lp parport autofs4 btrfs xor raid6_pq
> [ 186.678631] usbhid nouveau ttm i915 rtsx_pci_sdmmc mxm_wmi i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops psmouse drm ahci rtsx_pci nvme nvme_core libahci i2c_hid hid pinctrl_sunrisepoint video wmi pinctrl_intel fjes [last unloaded: brcmfmac]
> [ 186.678646] CPU: 2 PID: 7140 Comm: wpa_supplicant Not tainted 4.8.0-rc1+ #8
> [ 186.678647] Hardware name: Dell Inc. XPS 15 9550/0N7TVV, BIOS 01.02.00 04/07/2016
> [ 186.678648] 0000000000000000 ffff9d8c64b5b900 ffffffff98442f23 ffff9d8c64b5b950
> [ 186.678651] 0000000000000000 ffff9d8c64b5b940 ffffffff9808b22b 00001d790000000d
> [ 186.678653] ffffffff98c75e78 000000000000026c 0000000000000000 ffff9d8c2706d058
> [ 186.678655] Call Trace:
> [ 186.678659] [<ffffffff98442f23>] dump_stack+0x85/0xc2
> [ 186.678666] [<ffffffff9808b22b>] __warn+0xcb/0xf0
> [ 186.678668] [<ffffffff9808b29f>] warn_slowpath_fmt+0x4f/0x60
> [ 186.678671] [<ffffffff980d9090>] ? prepare_to_wait_event+0x60/0x100
> [ 186.678672] [<ffffffff980d9090>] ? prepare_to_wait_event+0x60/0x100
> [ 186.678674] [<ffffffff980b922c>] __might_sleep+0x7c/0x80
> [ 186.678680] [<ffffffff988b0853>] mutex_lock_nested+0x33/0x3b0
> [ 186.678682] [<ffffffff980e5d8d>] ? trace_hardirqs_on+0xd/0x10
> [ 186.678689] [<ffffffffc0c57d2d>] brcmf_cfg80211_wait_vif_event+0xcd/0x130 [brcmfmac]
> [ 186.678691] [<ffffffff980d9190>] ? wake_atomic_t_function+0x60/0x60
> [ 186.678697] [<ffffffffc0c628e9>] brcmf_p2p_del_vif+0xf9/0x220 [brcmfmac]
> [ 186.678702] [<ffffffffc0c57fab>] brcmf_cfg80211_del_iface+0x21b/0x270 [brcmfmac]
> [ 186.678716] [<ffffffffc0b0539e>] nl80211_del_interface+0xfe/0x3a0 [cfg80211]
> [ 186.678718] [<ffffffff987ca335>] genl_family_rcv_msg+0x1b5/0x370
> [ 186.678720] [<ffffffff980e5d8d>] ? trace_hardirqs_on+0xd/0x10
> [ 186.678721] [<ffffffff987ca56d>] genl_rcv_msg+0x7d/0xb0
> [ 186.678722] [<ffffffff987ca4f0>] ? genl_family_rcv_msg+0x370/0x370
> [ 186.678724] [<ffffffff987c9a47>] netlink_rcv_skb+0x97/0xb0
> [ 186.678726] [<ffffffff987ca168>] genl_rcv+0x28/0x40
> [ 186.678727] [<ffffffff987c93c3>] netlink_unicast+0x1d3/0x2f0
> [ 186.678729] [<ffffffff987c933b>] ? netlink_unicast+0x14b/0x2f0
> [ 186.678731] [<ffffffff987c97cb>] netlink_sendmsg+0x2eb/0x3a0
> [ 186.678733] [<ffffffff9876dad8>] sock_sendmsg+0x38/0x50
> [ 186.678734] [<ffffffff9876e4df>] ___sys_sendmsg+0x27f/0x290
> [ 186.678737] [<ffffffff9828b935>] ? mntput_no_expire+0x5/0x3f0
> [ 186.678739] [<ffffffff9828b9be>] ? mntput_no_expire+0x8e/0x3f0
> [ 186.678741] [<ffffffff9828b935>] ? mntput_no_expire+0x5/0x3f0
> [ 186.678743] [<ffffffff9828bd44>] ? mntput+0x24/0x40
> [ 186.678744] [<ffffffff98267830>] ? __fput+0x190/0x200
> [ 186.678746] [<ffffffff9876f125>] __sys_sendmsg+0x45/0x80
> [ 186.678748] [<ffffffff9876f172>] SyS_sendmsg+0x12/0x20
> [ 186.678749] [<ffffffff988b5680>] entry_SYSCALL_64_fastpath+0x23/0xc1
> [ 186.678751] [<ffffffff980e2b8f>] ? trace_hardirqs_off_caller+0x1f/0xc0
> [ 186.678752] ---[ end trace e224d66c5d8408b5 ]---

Acked-by: Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx>
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> ---
> .../broadcom/brcm80211/brcmfmac/cfg80211.c | 26 ++++++++++----------
> .../broadcom/brcm80211/brcmfmac/cfg80211.h | 2 +-
> 2 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> index 2628d5e..5db56a7 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> @@ -5635,7 +5635,7 @@ static s32 brcmf_notify_vif_event(struct brcmf_if *ifp,
> ifevent->action, ifevent->flags, ifevent->ifidx,
> ifevent->bsscfgidx);
>
> - mutex_lock(&event->vif_event_lock);
> + spin_lock(&event->vif_event_lock);
> event->action = ifevent->action;
> vif = event->vif;
>
> @@ -5643,7 +5643,7 @@ static s32 brcmf_notify_vif_event(struct brcmf_if *ifp,
> case BRCMF_E_IF_ADD:
> /* waiting process may have timed out */
> if (!cfg->vif_event.vif) {
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
> return -EBADF;
> }
>
> @@ -5654,24 +5654,24 @@ static s32 brcmf_notify_vif_event(struct brcmf_if *ifp,
> ifp->ndev->ieee80211_ptr = &vif->wdev;
> SET_NETDEV_DEV(ifp->ndev, wiphy_dev(cfg->wiphy));
> }
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
> wake_up(&event->vif_wq);
> return 0;
>
> case BRCMF_E_IF_DEL:
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
> /* event may not be upon user request */
> if (brcmf_cfg80211_vif_event_armed(cfg))
> wake_up(&event->vif_wq);
> return 0;
>
> case BRCMF_E_IF_CHANGE:
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
> wake_up(&event->vif_wq);
> return 0;
>
> default:
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
> break;
> }
> return -EINVAL;
> @@ -5792,7 +5792,7 @@ static void wl_deinit_priv(struct brcmf_cfg80211_info *cfg)
> static void init_vif_event(struct brcmf_cfg80211_vif_event *event)
> {
> init_waitqueue_head(&event->vif_wq);
> - mutex_init(&event->vif_event_lock);
> + spin_lock_init(&event->vif_event_lock);
> }
>
> static s32 brcmf_dongle_roam(struct brcmf_if *ifp)
> @@ -6691,9 +6691,9 @@ static inline bool vif_event_equals(struct brcmf_cfg80211_vif_event *event,
> {
> u8 evt_action;
>
> - mutex_lock(&event->vif_event_lock);
> + spin_lock(&event->vif_event_lock);
> evt_action = event->action;
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
> return evt_action == action;
> }
>
> @@ -6702,10 +6702,10 @@ void brcmf_cfg80211_arm_vif_event(struct brcmf_cfg80211_info *cfg,
> {
> struct brcmf_cfg80211_vif_event *event = &cfg->vif_event;
>
> - mutex_lock(&event->vif_event_lock);
> + spin_lock(&event->vif_event_lock);
> event->vif = vif;
> event->action = 0;
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
> }
>
> bool brcmf_cfg80211_vif_event_armed(struct brcmf_cfg80211_info *cfg)
> @@ -6713,9 +6713,9 @@ bool brcmf_cfg80211_vif_event_armed(struct brcmf_cfg80211_info *cfg)
> struct brcmf_cfg80211_vif_event *event = &cfg->vif_event;
> bool armed;
>
> - mutex_lock(&event->vif_event_lock);
> + spin_lock(&event->vif_event_lock);
> armed = event->vif != NULL;
> - mutex_unlock(&event->vif_event_lock);
> + spin_unlock(&event->vif_event_lock);
>
> return armed;
> }
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.h
> index 7d77f86..8889832 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.h
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.h
> @@ -227,7 +227,7 @@ struct escan_info {
> */
> struct brcmf_cfg80211_vif_event {
> wait_queue_head_t vif_wq;
> - struct mutex vif_event_lock;
> + spinlock_t vif_event_lock;
> u8 action;
> struct brcmf_cfg80211_vif *vif;
> };
>