mutexLock inside __fflush_unlocked fails after psh run prog

[anglov]

I put some trap in mutexLock code (thanks @xvuko for asserion test as an inspiration)

diff --git a/sys/threads.c b/sys/threads.c
index 42ecf87..f7e5c2a 100644
--- a/sys/threads.c
+++ b/sys/threads.c
@@ -17,10 +17,17 @@
 #include <errno.h>
 
 
+static int trap() {
+       while(1) {
+       }
+}
+
 int mutexLock(handle_t m)
 {
        int err;
        while ((err = phMutexLock(m)) == -EINTR) ;
+       if (err < 0)
+               trap();
        return err;
 }

Then attempt to run app via psh (it can be just typed aa in psh)

The traps hits from execve path in from __flush_unlocked.

handle_t seems to have resonable value (probably from parent after (v)fork) but it not exist for the newly forked process

Backtrace below

#0  mutexLock (m=5) at /path/to/project/libphoenix/sys/threads.c:30
#1  0x0803acd0 in __fflush_unlocked (lock=1, stream=<optimized out>) at /path/to/project/libphoenix/stdio/file.c:637
#2  0x08040aea in execve (file=0x20021c20 "as", argv=argv@entry=0x200175c0 <phfs_common+884>, envp=0x20019ffc) at /path/to/project/libphoenix/unistd/sys.c:106
#3  0x08040d3c in execv (path=<optimized out>, argv=argv@entry=0x200175c0 <phfs_common+884>) at /path/to/project/libphoenix/unistd/sys.c:94
#4  0x0803397a in psh_runfile (argc=<optimized out>, argv=0x200175c0 <phfs_common+884>) at /path/to/project/phoenix-rtos-utils/psh/runfile/runfile.c:51
#5  0x0802ae42 in psh_run (console=0x80416f0 "/dev/console", exitable=1) at /path/to/project/phoenix-rtos-utils/psh/pshapp/pshapp.c:1731
#6  psh_pshapp (argc=<optimized out>, argv=<optimized out>) at /path/to/project/phoenix-rtos-utils/psh/pshapp/pshapp.c:1806
#7  0x0802949e in main (argc=1, argv=0x20019ff4) at /path/to/project/phoenix-rtos-utils/psh/psh.c:182
#8  0x0802967c in _startc (cleanup=0x0, argc=1, argv=0x20019ff4, env=<optimized out>) at /path/to/project/libphoenix/crt0-common.c:92
#9  0x08012058 in process_exec (current=0x0, spawn=0xffffffcc) at /path/to/project/phoenix-rtos-kernel/proc/process.c:1130

I debug it on armv7m4-stm32l4-nucleo, but issues probably hits all architectures.

[astalke]

I've reproduced the issue on ia32-generic-qemu.

(gdb) backtrace 
#0  mutexLock (m=4) at /path-to-project/phoenix-rtos-project/libphoenix/sys/threads.c:20
#1  0x0805ede5 in __fflush_unlocked (lock=lock@entry=1, stream=0x0)
    at /path-to-project/phoenix-rtos-project/libphoenix/stdio/file.c:637
#2  0x0805f4ef in __fflush_unlocked (lock=1, stream=0x0)
    at /path-to-project/phoenix-rtos-project/libphoenix/stdio/file.c:636
#3  0x08068493 in execve (file=0x212a "/bin/bind", argv=0x21a8, envp=0x2208)
    at /path-to-project/phoenix-rtos-project/libphoenix/unistd/sys.c:106
#4  0x080688b6 in execv (path=0x212a "/bin/bind", argv=0x21a8)
    at /path-to-project/phoenix-rtos-project/libphoenix/unistd/sys.c:94
#5  0x08049d75 in psh_runscript (path=path@entry=0xbfffffd8 "/etc/rc.psh")
    at /path-to-project/phoenix-rtos-project/phoenix-rtos-utils/psh/pshapp/pshapp.c:1348
#6  0x0804a180 in psh_pshapp (argv=<optimized out>, argc=<optimized out>)
    at /path-to-project/phoenix-rtos-project/phoenix-rtos-utils/psh/pshapp/pshapp.c:1802
#7  psh_pshapp (argc=<optimized out>, argv=<optimized out>)
    at /path-to-project/phoenix-rtos-project/phoenix-rtos-utils/psh/pshapp/pshapp.c:1771
#8  0x08048774 in main (argc=<optimized out>, argv=<optimized out>)
    at /path-to-project/phoenix-rtos-project/phoenix-rtos-utils/psh/psh.c:182

[astalke]

Apparently it is caused by copying resources from parent only in fork, but not in vfork.