Exception 0 in LWIP2 on DHCP renew with WIFI_OFF #5667
Description
Basic Infos
- [X ] This issue complies with the issue POLICY doc.
- [X ] I have read the documentation at readthedocs and the issue is not addressed there.
- I have tested that the issue is present in current master branch (aka latest git).
- [X ] I have searched the issue tracker for a similar issue.
- [X ] If there is a stack dump, I have decoded it.
- [X ] I have filled out all fields below.
Platform
- Hardware: [ESP-12]
- Core Version: [Core:2_4_2 SDK:2.2.1(cfd48f3) LWIP:2.0.3]
- Development Env: [Platformio]
- Operating System: [Windows]
Settings in IDE
- Module: [Generic ESP8266 Module]
- Flash Mode: [qio]
- Flash Size: [4MB]
- lwip Variant: [v2 Lower Memory]
- Reset Method: [nodemcu]
- Flash Frequency: [40Mhz]
- CPU Frequency: [160MHz]
- Upload Using: [SERIAL]
- Upload Speed: [115200] (serial upload only)
Problem Description
Exception 0: interaction between application context printf and interrupt context printf
Detailed problem description goes here.
I'm experiencing periodic Exception 0s and the stack trace shows it is happening during vsnprintf in the LWIP stack when it's handling a DHCP timeout/renew (probably when WiFi is off). The exception address is always part of a printf format string from the application context. The particular address/string isn't the same in each exception, but the stack trace always ends at _vsnprintf_r and the exception address is always part of an application Serial.printf_P format string. In the example provided below, the exception address is 0x2C75253D which is ASCII "=%u," which only exists at one place in the code (see instruction below).
I first guessed that this might be a case of the app context stack overflowing into the ISR stack and tried increasing CONT_STACKSIZE to 6K but the exception still takes place. Moreover, the stack dump isn't anywhere near 4K (it's 768 bytes deep in the stack dump below)...so it must be something else (how big is the interrupt stack?)
All of the application code is running in the application context (no application ISRs). Any ideas would be much appreciated.
MCVE Sketch
Serial.printf_P(PSTR("TIMESLOT: %u (ts=%u, nbr=%u, ch=%u, mode=%u)"), time, slot, neighbors[slot].id, new_channel, mode); Debug Messages
>>>stack>>> 3ffffca0: 4021a438 00000030 00000008 ffffffff 3ffffcb0: 4021a48c ffffffff 0000003f 3ffe983c 3ffffcc0: 3ffffed0 3ffffea0 00000008 3ffe983c 3ffffcd0: 00000040 3ffe983c 00000001 00000040 3ffffce0: 3ffe8304 3fff1cd0 3fff0828 3ffe983c 3ffffcf0: 00000000 3ffe8304 3ffffda0 4021c8b8 3ffffd00: 3fff3d32 0000002a 0000001f 00000000 3ffffd10: 00000032 0000001c 00000060 3fff3b55 3ffffd20: 3fff3b20 3fff3b20 3fff3cfc 4021e496 3ffffd30: 4021e82b 3fff3cfc 3fff3d32 4021e834 3ffffd40: 00000608 3ffeafdf 00000067 00000003 3ffffd50: 00000000 00000000 00000000 3fff3b55 3ffffd60: 3fff3d40 00000000 3fff3cfc 4022487f 3ffffd70: 3fff3b20 3fff3b55 3ffeafdf 3ffeafd9 3ffffd80: 00000001 0000003d 0000003d 3fff0828 3ffffd90: 3fff1cd0 3ffe8304 00000040 3fff39bc 3ffffda0: 3fff3b20 00000000 3fff7644 40224a6a 3ffffdb0: 3fff4278 00000001 3ffef540 3fff7694 3ffffdc0: 3fff3b20 3fff4278 3fff7644 40224c1d 3ffffdd0: 00000000 00000000 00000000 00000000 3ffffde0: 40103462 00000021 7fffffff 3fff7694 3ffffdf0: 3fff7644 3fff4278 3fff3b20 40224de8 3ffffe00: 40230000 3ffffec0 3ffefff8 00000016 3ffffe10: 00000014 3fff4278 3fff7644 4022595c 3ffffe20: 3ffffed0 3ffffea0 00000008 00000016 3ffffe30: 3fff3b24 000000ff 00000000 00000011 3ffffe40: 3fff3ab8 4010325e 00040000 402137f4 3ffffe50: 00000011 00000001 64657463 3fff7644 3ffffe60: 3fff4278 3fff76a8 3fff429c 402259ea 3ffffe70: 3fff3b20 00000000 00000000 4021e91f 3ffffe80: 4000050c 00000000 3fff4254 402223ef 3ffffe90: 3fff3b20 00000030 0000001d 40221a5a 3ffffea0: 3fff7644 3fff3b20 3fff3b24 00000043 3ffffeb0: 00000000 00000000 00000000 fffffffb 3ffffec0: 3fff3b20 00000003 3fff4254 fffffffb 3ffffed0: 00000000 3fff3b20 3fff4254 4022245c 3ffffee0: 00000000 3fff3b20 3fff4254 40224293 3ffffef0: 00000000 3fff3b20 3fff4254 402245be 3fffff00: 4021faa4 3fff3774 3fff3c44 401006dc 3fffff10: 0ffabdd3 3ffeb1d4 3ffeb070 3fff3770 3fffff20: 4021faa4 3fff3774 3ffeb058 4021fab2 3fffff30: 35fc1297 3fff3774 00000017 4021fb68 3fffff40: 3ffeb058 3ffeb1d4 10dec254 00000000 3fffff50: 40251ebc 3fff0658 3fff0680 60000600 3fffff60: 35fc1297 3fff0680 3fff0658 40251ec9 3fffff70: 40251f0e 3fffdab0 00000000 3fffdcb0 3fffff80: 3fff0698 3fffdad0 3fff35bc 402150c7 3fffff90: 40000f49 40000f49 3fffdab0 40000f49 3fffffa0: 40000e19 40001878 00000002 00000000 <<<stack<<< Decoding 37 results 0x4021a438: _vsnprintf_r at /Users/igrokhotkov/e/newlib-xtensa/xtensa-lx106-elf/newlib/libc/stdio/../../../.././newlib/libc/stdio/vsnprintf.c line 72 0x4021a48c: vsnprintf at /Users/igrokhotkov/e/newlib-xtensa/xtensa-lx106-elf/newlib/libc/stdio/../../../.././newlib/libc/stdio/vsnprintf.c line 42 0x4021c8b8: _svfprintf_r at /Users/igrokhotkov/e/newlib-xtensa/xtensa-lx106-elf/newlib/libc/stdio/../../../.././newlib/libc/stdio/nano-vfprintf.c line 531 0x4021e496: new_linkoutput at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/glue-lwip/lwip-git.c line 259 0x4021e82b: ethernet_output at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/netif/ethernet.c line 305 0x4021e834: ethernet_output at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/netif/ethernet.c line 305 0x4022487f: etharp_raw at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/etharp.c line 626 0x40224a6a: etharp_request at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/etharp.c line 1203 0x40224c1d: etharp_query at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/etharp.c line 981 0x40103462: lmacProcessTxSuccess at ?? line ? 0x40224de8: etharp_output_LWIP2 at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/etharp.c line 887 0x40230000: scan_parse_beacon at ?? line ? 0x4022595c: ip4_output_if_opt_src at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/ip4.c line 962 0x4010325e: lmacProcessTXStartData at ?? line ? 0x402137f4: Print::printf(char const*, ...) at C:\Users\david\.platformio\packages\framework-arduinoespressif8266\cores\esp8266/Print.cpp line 220 0x402259ea: ip4_output_if_src at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/ip4.c line 801 0x4021e91f: ip_chksum_pseudo at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/inet_chksum.c line 542 0x402223ef: udp_sendto_if_src at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/udp.c line 463 0x40221a5a: pbuf_alloc_LWIP2 at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/pbuf.c line 1306 0x4022245c: udp_sendto_if at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/udp.c line 463 0x40224293: dhcp_renew at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/dhcp.c line 1157 0x402245be: dhcp_t1_timeout at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/dhcp.c line 545 : (inlined by) dhcp_coarse_tmr at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/ipv4/dhcp.c line 433 0x4021faa4: cyclic_timer at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/timeouts.c line 165 0x401006dc: free at C:\Users\david\.platformio\packages\framework-arduinoespressif8266\cores\esp8266\umm_malloc/umm_malloc.c line 1755 0x4021faa4: cyclic_timer at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/timeouts.c line 165 0x4021fab2: cyclic_timer at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/timeouts.c line 171 0x4021fb68: sys_check_timeouts at /local/users/gauchard/arduino/arduino_esp8266/origin/tools/sdk/lwip2/builder/lwip2-src/src/core/timeouts.c line 351 0x40251ebc: ets_timer_handler_isr at ?? line ? 0x40251ec9: ets_timer_handler_isr at ?? line ? 0x40251f0e: ets_timer_handler_isr at ?? line ? 0x402150c7: loop_task at C:\Users\david\.platformio\packages\framework-arduinoespressif8266\cores\esp8266/core_esp8266_main.cpp line 133