[GitHub] [incubator-nuttx] btashton commented on issue #2663: kthread_create hangs waiting on semaphore while trying to copy file descriptors

[GitBox <gi...@apache.org>]

btashton commented on issue #2663:
URL: https://github.com/apache/incubator-nuttx/issues/2663#issuecomment-770651598


   @xiaoxiang781216 I just noticed something similar when trying to create a kernel thread off of a call in `sim_bringup()` (I'm add usbhost support via libusb).  I get a segfault because in `sched_dupfiles` `rtcb->group` is 0 which means parent and child are both invalid
   
   ```c
   Thread 1 "nuttx" received signal SIGSEGV, Segmentation fault.
                                                                sched_dupfiles (tcb=0x7ffff3e295d0) at group/group_setuptaskfiles.c:103
   103           if (parent[i].f_inode &&
   Missing separate debuginfos, use: dnf debuginfo-install libgcc-10.2.1-9.fc33.x86_64 libusbx-1.0.23-2.fc33.x86_64 systemd-libs-246.7-2.fc33.x86_64 zlib-1.2.11-23.fc33.x86_64
   (gdb) p parent
   $1 = (struct file *) 0x78
   (gdb) list
   98            /* Check if this file is opened by the parent.  We can tell if
   99             * if the file is open because it contain a reference to a non-NULL
   100            * i-node structure.
   101            */
   102
   103           if (parent[i].f_inode &&
   104               (parent[i].f_oflags & O_CLOEXEC) == 0)
   105             {
   106               /* Yes... duplicate it for the child */
   107
   (gdb) p rtcb
   $2 = (struct tcb_s *) 0x7ffff3e27c90
   (gdb) p rtcb->group
   $3 = (struct task_group_s *) 0x0
   (gdb) p rtcb*
   A syntax error in expression, near `'.
   (gdb) p *rtcb
   $4 = {flink = 0x43f8a0 <g_idletcb>, blink = 0x7ffff7f38020 <_IO_strn_jumps>, group = 0x0, pid = 1, start = 0x402184 <nxtask_start>, entry = {pthread = 0x408e78 <nsh_main>, main = 0x408e78 <nsh_main>}, sched_priority = 100 'd', 
     init_priority = 100 'd', task_state = 3 '\003', flags = 0, lockcount = 0, errcode = 0, waitdog = {next = 0x0, func = 0x85b82ce26aee8900, lag = 0, flags = 0 '\000', arg = 9635500753727424768}, adj_stack_size = 140737285094944, 
     stack_alloc_ptr = 0x85b82ce26aee8900, adj_stack_ptr = 0x4412a0, waitsem = 0x0, sigprocmask = 4091706928, sigwaitmask = 32767, sigpendactionq = {head = 0x4412a0, tail = 0xffffffff}, sigpostedq = {head = 0x3, tail = 0x4441d0}, sigunbinfo = {
       si_signo = 5 '\005', si_code = 23 '\027', si_errno = 232 '\350', si_value = {sival_int = 48, sival_ptr = 0x3000000030}, si_pid = 32304, si_status = 32767}, msgwaitq = 0x7ffff3e27d60, mhead = 0x85b82ce26aee8900, xcp = {
       sigdeliver = 0x7ffff3e27e1c, regs = {4539616, 0, 0, 0, 140737353413158, 4473296, 140737351999557, 140737351996080}}, name = "x\030\371\367\377\177\000\000\000\000\000\000\000\000\000\000 \203\363\367\t\000\000\000\340DE\000\000\000\000"}
   (gdb) p rtcb->group
   $5 = (struct task_group_s *) 0x0
   ```


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