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apache / nuttx

Apache NuttX is a mature, real-time embedded operating system (RTOS)
https://nuttx.apache.org/
Apache License 2.0
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usbtrace causes crash #12181

Open Virus-V opened 6 months ago

Virus-V commented 6 months ago

When I was debugging the STM32F405 USB function, I encountered a crash.

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It seemed that the data structure was damaged.

The cause of this problem is that the interrupt was responded to in the critical section.

This problem only occurred after I turned on the USB DEBUG function.

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I found that in the syslog_putc function, different output functions are called according to the current calling context.

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However, it does not handle the current situation in the critical section, resulting in task scheduling and interrupts being turned on in the critical section.

acassis commented 6 months ago

@Virus-V nice work finding and debugging this issue! Kudos!!!

@xiaoxiang781216 @raiden00pl any suggestion?

@Virus-V maybe using RAMLOG as SYSLOG instead of SYSLOG over serial could help, them you just run dmesg later to see what happened.

Note: take care with using USB Trace, as Greg explained some years ago: when you add tracing you are changing the timing of USB and it could introduce issues.

xiaoxiang781216 commented 6 months ago

This is a known issue we found many time before: https://github.com/apache/nuttx/issues/1138 One possible solution postpone the preemption until leave_critical_section.

Virus-V commented 6 months ago

It is unsafe to call syslog in a critical section.

Not only usbdev, there are similar codes in other drivers in nuttx (such as drivers/timers/pwm.c).