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authorJiri Kosina <jkosina@suse.cz>2014-09-02 05:03:12 -0400
committerBryan Wu <cooloney@gmail.com>2014-09-02 13:02:13 -0400
commit9067359faf890b3a18ab38c792d458fba77b32b4 (patch)
tree1520d8094cdf64033f95452f4b7649e50c597afe /drivers/leds/led-core.c
parent69e273c0b0a3c337a521d083374c918dc52c666f (diff)
Revert "leds: convert blink timer to workqueue"
This reverts commit 8b37e1bef5a6b60e949e28a4db3006e4b00bd758. It's broken as it changes led_blink_set() in a way that it can now sleep (while synchronously waiting for workqueue to be cancelled). That's a problem, because it's possible that this function gets called from atomic context (tpt_trig_timer() takes a readlock and thus disables preemption). This has been brought up 3 weeks ago already [1] but no proper fix has materialized, and I keep seeing the problem since 3.17-rc1. [1] https://lkml.org/lkml/2014/8/16/128 BUG: sleeping function called from invalid context at kernel/workqueue.c:2650 in_atomic(): 1, irqs_disabled(): 0, pid: 2335, name: wpa_supplicant 5 locks held by wpa_supplicant/2335: #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff814c7c92>] rtnl_lock+0x12/0x20 #1: (&wdev->mtx){+.+.+.}, at: [<ffffffffc06e649c>] cfg80211_mgd_wext_siwessid+0x5c/0x180 [cfg80211] #2: (&local->mtx){+.+.+.}, at: [<ffffffffc0817dea>] ieee80211_prep_connection+0x17a/0x9a0 [mac80211] #3: (&local->chanctx_mtx){+.+.+.}, at: [<ffffffffc08081ed>] ieee80211_vif_use_channel+0x5d/0x2a0 [mac80211] #4: (&trig->leddev_list_lock){.+.+..}, at: [<ffffffffc081e68c>] tpt_trig_timer+0xec/0x170 [mac80211] CPU: 0 PID: 2335 Comm: wpa_supplicant Not tainted 3.17.0-rc3 #1 Hardware name: LENOVO 7470BN2/7470BN2, BIOS 6DET38WW (2.02 ) 12/19/2008 ffff8800360b5a50 ffff8800751f76d8 ffffffff8159e97f ffff8800360b5a30 ffff8800751f76e8 ffffffff810739a5 ffff8800751f77b0 ffffffff8106862f ffffffff810685d0 0aa2209200000000 ffff880000000004 ffff8800361c59d0 Call Trace: [<ffffffff8159e97f>] dump_stack+0x4d/0x66 [<ffffffff810739a5>] __might_sleep+0xe5/0x120 [<ffffffff8106862f>] flush_work+0x5f/0x270 [<ffffffff810685d0>] ? mod_delayed_work_on+0x80/0x80 [<ffffffff810945ca>] ? mark_held_locks+0x6a/0x90 [<ffffffff81068a5f>] ? __cancel_work_timer+0x6f/0x100 [<ffffffff810946ed>] ? trace_hardirqs_on_caller+0xfd/0x1c0 [<ffffffff81068a6b>] __cancel_work_timer+0x7b/0x100 [<ffffffff81068b0e>] cancel_delayed_work_sync+0xe/0x10 [<ffffffff8147cf3b>] led_blink_set+0x1b/0x40 [<ffffffffc081e6b0>] tpt_trig_timer+0x110/0x170 [mac80211] [<ffffffffc081ecdd>] ieee80211_mod_tpt_led_trig+0x9d/0x160 [mac80211] [<ffffffffc07e4278>] __ieee80211_recalc_idle+0x98/0x140 [mac80211] [<ffffffffc07e59ce>] ieee80211_idle_off+0xe/0x10 [mac80211] [<ffffffffc0804e5b>] ieee80211_add_chanctx+0x3b/0x220 [mac80211] [<ffffffffc08062e4>] ieee80211_new_chanctx+0x44/0xf0 [mac80211] [<ffffffffc080838a>] ieee80211_vif_use_channel+0x1fa/0x2a0 [mac80211] [<ffffffffc0817df8>] ieee80211_prep_connection+0x188/0x9a0 [mac80211] [<ffffffffc081c246>] ieee80211_mgd_auth+0x256/0x2e0 [mac80211] [<ffffffffc07eab33>] ieee80211_auth+0x13/0x20 [mac80211] [<ffffffffc06cb006>] cfg80211_mlme_auth+0x106/0x270 [cfg80211] [<ffffffffc06ce085>] cfg80211_conn_do_work+0x155/0x3b0 [cfg80211] [<ffffffffc06cf670>] cfg80211_connect+0x3f0/0x540 [cfg80211] [<ffffffffc06e6148>] cfg80211_mgd_wext_connect+0x158/0x1f0 [cfg80211] [<ffffffffc06e651e>] cfg80211_mgd_wext_siwessid+0xde/0x180 [cfg80211] [<ffffffffc06e36c0>] ? cfg80211_wext_giwessid+0x50/0x50 [cfg80211] [<ffffffffc06e36dd>] cfg80211_wext_siwessid+0x1d/0x40 [cfg80211] [<ffffffff81584d0c>] ioctl_standard_iw_point+0x14c/0x3e0 [<ffffffff810946ed>] ? trace_hardirqs_on_caller+0xfd/0x1c0 [<ffffffff8158502a>] ioctl_standard_call+0x8a/0xd0 [<ffffffff81584fa0>] ? ioctl_standard_iw_point+0x3e0/0x3e0 [<ffffffff81584b76>] wireless_process_ioctl.constprop.10+0xb6/0x100 [<ffffffff8158521d>] wext_handle_ioctl+0x5d/0xb0 [<ffffffff814cfb29>] dev_ioctl+0x329/0x620 [<ffffffff810946ed>] ? trace_hardirqs_on_caller+0xfd/0x1c0 [<ffffffff8149c7f2>] sock_ioctl+0x142/0x2e0 [<ffffffff811b0140>] do_vfs_ioctl+0x300/0x520 [<ffffffff815a67fb>] ? sysret_check+0x1b/0x56 [<ffffffff810946ed>] ? trace_hardirqs_on_caller+0xfd/0x1c0 [<ffffffff811b03e1>] SyS_ioctl+0x81/0xa0 [<ffffffff815a67d6>] system_call_fastpath+0x1a/0x1f wlan0: send auth to 00:0b:6b:3c:8c:e4 (try 1/3) wlan0: authenticated wlan0: associate with 00:0b:6b:3c:8c:e4 (try 1/3) wlan0: RX AssocResp from 00:0b:6b:3c:8c:e4 (capab=0x431 status=0 aid=2) wlan0: associated IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready cfg80211: Calling CRDA for country: NA wlan0: Limiting TX power to 27 (27 - 0) dBm as advertised by 00:0b:6b:3c:8c:e4 ================================= [ INFO: inconsistent lock state ] 3.17.0-rc3 #1 Not tainted --------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/0/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ((&(&led_cdev->blink_work)->work)){+.?...}, at: [<ffffffff810685d0>] flush_work+0x0/0x270 {SOFTIRQ-ON-W} state was registered at: [<ffffffff81094dbe>] __lock_acquire+0x30e/0x1a30 [<ffffffff81096c81>] lock_acquire+0x91/0x110 [<ffffffff81068608>] flush_work+0x38/0x270 [<ffffffff81068a6b>] __cancel_work_timer+0x7b/0x100 [<ffffffff81068b0e>] cancel_delayed_work_sync+0xe/0x10 [<ffffffff8147cf3b>] led_blink_set+0x1b/0x40 [<ffffffffc081e6b0>] tpt_trig_timer+0x110/0x170 [mac80211] [<ffffffffc081ecdd>] ieee80211_mod_tpt_led_trig+0x9d/0x160 [mac80211] [<ffffffffc07e4278>] __ieee80211_recalc_idle+0x98/0x140 [mac80211] [<ffffffffc07e59ce>] ieee80211_idle_off+0xe/0x10 [mac80211] [<ffffffffc0804e5b>] ieee80211_add_chanctx+0x3b/0x220 [mac80211] [<ffffffffc08062e4>] ieee80211_new_chanctx+0x44/0xf0 [mac80211] [<ffffffffc080838a>] ieee80211_vif_use_channel+0x1fa/0x2a0 [mac80211] [<ffffffffc0817df8>] ieee80211_prep_connection+0x188/0x9a0 [mac80211] [<ffffffffc081c246>] ieee80211_mgd_auth+0x256/0x2e0 [mac80211] [<ffffffffc07eab33>] ieee80211_auth+0x13/0x20 [mac80211] [<ffffffffc06cb006>] cfg80211_mlme_auth+0x106/0x270 [cfg80211] [<ffffffffc06ce085>] cfg80211_conn_do_work+0x155/0x3b0 [cfg80211] [<ffffffffc06cf670>] cfg80211_connect+0x3f0/0x540 [cfg80211] [<ffffffffc06e6148>] cfg80211_mgd_wext_connect+0x158/0x1f0 [cfg80211] [<ffffffffc06e651e>] cfg80211_mgd_wext_siwessid+0xde/0x180 [cfg80211] [<ffffffffc06e36dd>] cfg80211_wext_siwessid+0x1d/0x40 [cfg80211] [<ffffffff81584d0c>] ioctl_standard_iw_point+0x14c/0x3e0 [<ffffffff8158502a>] ioctl_standard_call+0x8a/0xd0 [<ffffffff81584b76>] wireless_process_ioctl.constprop.10+0xb6/0x100 [<ffffffff8158521d>] wext_handle_ioctl+0x5d/0xb0 [<ffffffff814cfb29>] dev_ioctl+0x329/0x620 [<ffffffff8149c7f2>] sock_ioctl+0x142/0x2e0 [<ffffffff811b0140>] do_vfs_ioctl+0x300/0x520 [<ffffffff811b03e1>] SyS_ioctl+0x81/0xa0 [<ffffffff815a67d6>] system_call_fastpath+0x1a/0x1f irq event stamp: 493416 hardirqs last enabled at (493416): [<ffffffff81068a5f>] __cancel_work_timer+0x6f/0x100 hardirqs last disabled at (493415): [<ffffffff81067e9f>] try_to_grab_pending+0x1f/0x160 softirqs last enabled at (493408): [<ffffffff81053ced>] _local_bh_enable+0x1d/0x50 softirqs last disabled at (493409): [<ffffffff81054c75>] irq_exit+0xa5/0xb0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock((&(&led_cdev->blink_work)->work)); <Interrupt> lock((&(&led_cdev->blink_work)->work)); *** DEADLOCK *** 2 locks held by swapper/0/0: #0: (((&tpt_trig->timer))){+.-...}, at: [<ffffffff810b4c50>] call_timer_fn+0x0/0x180 #1: (&trig->leddev_list_lock){.+.?..}, at: [<ffffffffc081e68c>] tpt_trig_timer+0xec/0x170 [mac80211] stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.17.0-rc3 #1 Hardware name: LENOVO 7470BN2/7470BN2, BIOS 6DET38WW (2.02 ) 12/19/2008 ffffffff8246eb30 ffff88007c203b00 ffffffff8159e97f ffffffff81a194c0 ffff88007c203b50 ffffffff81599c29 0000000000000001 ffffffff00000001 ffff880000000000 0000000000000006 ffffffff81a194c0 ffffffff81093ad0 Call Trace: <IRQ> [<ffffffff8159e97f>] dump_stack+0x4d/0x66 [<ffffffff81599c29>] print_usage_bug+0x1f4/0x205 [<ffffffff81093ad0>] ? check_usage_backwards+0x140/0x140 [<ffffffff810944d3>] mark_lock+0x223/0x2b0 [<ffffffff81094d60>] __lock_acquire+0x2b0/0x1a30 [<ffffffff81096c81>] lock_acquire+0x91/0x110 [<ffffffff810685d0>] ? mod_delayed_work_on+0x80/0x80 [<ffffffffc081e5a0>] ? __ieee80211_get_rx_led_name+0x10/0x10 [mac80211] [<ffffffff81068608>] flush_work+0x38/0x270 [<ffffffff810685d0>] ? mod_delayed_work_on+0x80/0x80 [<ffffffff810945ca>] ? mark_held_locks+0x6a/0x90 [<ffffffff81068a5f>] ? __cancel_work_timer+0x6f/0x100 [<ffffffffc081e5a0>] ? __ieee80211_get_rx_led_name+0x10/0x10 [mac80211] [<ffffffff8109469d>] ? trace_hardirqs_on_caller+0xad/0x1c0 [<ffffffffc081e5a0>] ? __ieee80211_get_rx_led_name+0x10/0x10 [mac80211] [<ffffffff81068a6b>] __cancel_work_timer+0x7b/0x100 [<ffffffff81068b0e>] cancel_delayed_work_sync+0xe/0x10 [<ffffffff8147cf3b>] led_blink_set+0x1b/0x40 [<ffffffffc081e6b0>] tpt_trig_timer+0x110/0x170 [mac80211] [<ffffffff810b4cc5>] call_timer_fn+0x75/0x180 [<ffffffff810b4c50>] ? process_timeout+0x10/0x10 [<ffffffffc081e5a0>] ? __ieee80211_get_rx_led_name+0x10/0x10 [mac80211] [<ffffffff810b50ac>] run_timer_softirq+0x1fc/0x2f0 [<ffffffff81054805>] __do_softirq+0x115/0x2e0 [<ffffffff81054c75>] irq_exit+0xa5/0xb0 [<ffffffff810049b3>] do_IRQ+0x53/0xf0 [<ffffffff815a74af>] common_interrupt+0x6f/0x6f <EOI> [<ffffffff8147b56e>] ? cpuidle_enter_state+0x6e/0x180 [<ffffffff8147b732>] cpuidle_enter+0x12/0x20 [<ffffffff8108bba0>] cpu_startup_entry+0x330/0x360 [<ffffffff8158fb51>] rest_init+0xc1/0xd0 [<ffffffff8158fa90>] ? csum_partial_copy_generic+0x170/0x170 [<ffffffff81af3ff2>] start_kernel+0x44f/0x45a [<ffffffff81af399c>] ? set_init_arg+0x53/0x53 [<ffffffff81af35ad>] x86_64_start_reservations+0x2a/0x2c [<ffffffff81af36a0>] x86_64_start_kernel+0xf1/0xf4 Cc: Vincent Donnefort <vdonnefort@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Bryan Wu <cooloney@gmail.com>
Diffstat (limited to 'drivers/leds/led-core.c')
-rw-r--r--drivers/leds/led-core.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 4bb116867b88..71b40d3bf776 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -16,7 +16,6 @@
16#include <linux/module.h> 16#include <linux/module.h>
17#include <linux/rwsem.h> 17#include <linux/rwsem.h>
18#include <linux/leds.h> 18#include <linux/leds.h>
19#include <linux/workqueue.h>
20#include "leds.h" 19#include "leds.h"
21 20
22DECLARE_RWSEM(leds_list_lock); 21DECLARE_RWSEM(leds_list_lock);
@@ -52,7 +51,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
52 return; 51 return;
53 } 52 }
54 53
55 queue_delayed_work(system_wq, &led_cdev->blink_work, 1); 54 mod_timer(&led_cdev->blink_timer, jiffies + 1);
56} 55}
57 56
58 57
@@ -76,7 +75,7 @@ void led_blink_set(struct led_classdev *led_cdev,
76 unsigned long *delay_on, 75 unsigned long *delay_on,
77 unsigned long *delay_off) 76 unsigned long *delay_off)
78{ 77{
79 cancel_delayed_work_sync(&led_cdev->blink_work); 78 del_timer_sync(&led_cdev->blink_timer);
80 79
81 led_cdev->flags &= ~LED_BLINK_ONESHOT; 80 led_cdev->flags &= ~LED_BLINK_ONESHOT;
82 led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP; 81 led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
@@ -91,7 +90,7 @@ void led_blink_set_oneshot(struct led_classdev *led_cdev,
91 int invert) 90 int invert)
92{ 91{
93 if ((led_cdev->flags & LED_BLINK_ONESHOT) && 92 if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
94 delayed_work_pending(&led_cdev->blink_work)) 93 timer_pending(&led_cdev->blink_timer))
95 return; 94 return;
96 95
97 led_cdev->flags |= LED_BLINK_ONESHOT; 96 led_cdev->flags |= LED_BLINK_ONESHOT;
@@ -108,7 +107,7 @@ EXPORT_SYMBOL(led_blink_set_oneshot);
108 107
109void led_stop_software_blink(struct led_classdev *led_cdev) 108void led_stop_software_blink(struct led_classdev *led_cdev)
110{ 109{
111 cancel_delayed_work_sync(&led_cdev->blink_work); 110 del_timer_sync(&led_cdev->blink_timer);
112 led_cdev->blink_delay_on = 0; 111 led_cdev->blink_delay_on = 0;
113 led_cdev->blink_delay_off = 0; 112 led_cdev->blink_delay_off = 0;
114} 113}
@@ -117,7 +116,7 @@ EXPORT_SYMBOL_GPL(led_stop_software_blink);
117void led_set_brightness(struct led_classdev *led_cdev, 116void led_set_brightness(struct led_classdev *led_cdev,
118 enum led_brightness brightness) 117 enum led_brightness brightness)
119{ 118{
120 /* delay brightness setting if need to stop soft-blink work */ 119 /* delay brightness setting if need to stop soft-blink timer */
121 if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) { 120 if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
122 led_cdev->delayed_set_value = brightness; 121 led_cdev->delayed_set_value = brightness;
123 schedule_work(&led_cdev->set_brightness_work); 122 schedule_work(&led_cdev->set_brightness_work);