平台：msm8937+android7.1
- 问题和log
同样的代码在user版本上正常，但在userdebug版本上就有问题，设备反复重启。
[ 29.288033] lm3492hc_bklt_timer_func limit backlight,default 84 percent
[ 29.293755] lm3492hc_bklt_timer_func come in
[ 29.297948] BUG: sleeping function called from invalid context at /home/chenky/debug/svn185/trunk/kernel/msm-3.18/mm/slub.c:1281
[ 29.309536] in_atomic(): 1, irqs_disabled(): 0, pid: 709, name: installd
[ 29.316176] Preemption disabled at:[<ffffffc0000a72c8>] irq_exit+0x74/0xb0
[ 29.323046] ------------[ cut here ]------------
[ 29.327636] kernel BUG at /home/chenky/debug/svn185/trunk/kernel/msm-3.18/kernel/sched/qhmp_core.c:9180!
[ 29.337096] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[ 29.342565] Modules linked in:
[ 29.345607] CPU: 0 PID: 709 Comm: installd Tainted: G W 3.18.31-svn224 #13
[ 29.353502] Hardware name: Qualcomm Technologies, Inc. MSM8937-PMI8937 QRD SKU2 (DT)
[ 29.361231] task: ffffffc059228e00 ti: ffffffc0592e0000 task.ti: ffffffc0592e0000
[ 29.368698] PC is at __might_sleep+0x15c/0x16c
[ 29.373123] LR is at __might_sleep+0x15c/0x16c
…
[ 29.889266] Call trace:
[ 29.891703] [<ffffffc0000c7960>] __might_sleep+0x15c/0x16c
[ 29.897173] [<ffffffc0001ad2e4>] kmem_cache_alloc_trace+0x68/0x278
[ 29.903335] [<ffffffc0000f56e8>] request_threaded_irq+0x90/0x118
[ 29.909326] [<ffffffc0004130c4>] lm3492hc_bklt_timer_func+0xbc/0x110
[ 29.915660] [<ffffffc000103754>] call_timer_fn+0x98/0x1c4
[ 29.921040] [<ffffffc0001049f0>] run_timer_softirq+0x55c/0x614
[ 29.926858] [<ffffffc0000a6e8c>] __do_softirq+0x178/0x350
[ 29.932237] [<ffffffc0000a72c8>] irq_exit+0x74/0xb0
[ 29.937100] [<ffffffc0000f33c8>] __handle_domain_irq+0xb4/0xec
[ 29.942915] [<ffffffc000082560>] gic_handle_irq+0x68/0xa8
…
表示代码在原子上下文中休眠了。
BUG: sleeping function called from invalid context at是kernel\msm-3.18\kernel\sched\qhmp_core.c的__might_sleep()打印的
__might_sleep被might_sleep()调用，如下：
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
void __might_sleep(const char *file, int line, int preempt_offset);
/**
* might_sleep - annotation for functions that can sleep
*
* this macro will print a stack trace if it is executed in an atomic
* context (spinlock, irq-handler, ...).
*
* This is a useful debugging help to be able to catch problems early and not
* be bitten later when the calling function happens to sleep when it is not
* supposed to.
*/
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
#else
static inline void __might_sleep(const char *file, int line,
int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
#endif
ret = devm_request_irq(&pdev->dev,
ctrl_pdata->bklt_comm_irq,
lm3492hc_interrupt_handler, IRQF_TRIGGER_HIGH,//IRQF_TRIGGER_FALLING,
"lm3492hc_interrupt_handler", ctrl_pdata);
2. 解决方法
mdss_dsi_ctrl_probe()--->lm3492hc_bklt_timer_func()函数
lm3492hc_bklt_timer_func()函数调用了devm_request_irq来申请中断
ret = devm_request_irq(&pdev->dev,
ctrl_pdata->bklt_comm_irq,
lm3492hc_interrupt_handler, IRQF_TRIGGER_HIGH,//IRQF_TRIGGER_FALLING,
"lm3492hc_interrupt_handler", ctrl_pdata);
(1) 注释掉CONFIG_DEBUG_ATOMIC_SLEEP
#CONFIG_DEBUG_ATOMIC_SLEEP=y，注释掉这项，后就正常了
(2) 把devm_request_irq放在mdss_dsi_ctrl_probe()即可。
参考链接
https://blog.csdn.net/hp0773/article/details/12658501
request_irq引发BUG: sleeping function called from invalid context at mm/slab.c
http://bbs.chinaunix.net/thread-1929312-1-1.html