After 524d75ff ("Cygwin: open: Unlock fdtab before open_with_arch()"),
CI workflow shows that 'stress-ng --procfs ...' now hangs.
Testcase:
$ uname -r # not with 3.7.0-0.567.g161e3cb999fb.x86_64
3.7.0-0.569.g524d75ff7398.x86_64
$ cat proc-self-fd.c
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
static void * threadfunc(void * arg)
{
(void)arg;
for (int i = 0; i < 100000; i++) {
char path[32];
snprintf(path, sizeof(path), "/proc/self/fd/%d", i % 10);
int fd = open(path, O_RDONLY);
if (fd < 0) {
printf("%p#%06d: %s: errno=%d\n", pthread_self(), i, path, errno);
continue;
}
printf("%p#%06d: %s: fd=%d\n", pthread_self(), i, path, fd);
close(fd);
}
return NULL;
}
int main()
{
pthread_t t = NULL;
int ret = pthread_create(&t, NULL, threadfunc, NULL);
if (ret)
return 1;
threadfunc(NULL);
ret = pthread_join(t, NULL);
printf("pthread_join(%p, .)=%d\n", t, ret);
if (ret)
return 1;
return 0;
}
$ gcc -o proc-self-fd proc-self-fd.c
$ ./proc-self-fd
...
0xa00000500#001908: /proc/self/fd/8: errno=2
0xa00000010#001900: /proc/self/fd/0: fd=3
0xa00000500#001909: /proc/self/fd/9: errno=2
0xa00000010#001901: /proc/self/fd/1: errno=14<== EFAULT
[hangs, kill -9 does not work]
$ strace -o trace.log ./proc-self-fd
[taskkill /f /im proc-self-fd.exe in other window]
$ less trace.log
...
25 21725 [main] proc-self-fd 14876 fhandler_pty_slave::open_setup:
/dev/pty1 opened, usecount 3
61 21786 [main] proc-self-fd 14876 build_fh_pc: found an archetype
for (null)(136/1) io_handle 0x200
66 21852 [main] proc-self-fd 14876 build_fh_pc: fh 0x800008E40,
dev 00880001
71 21923 [main] proc-self-fd 14876 fhandler_base::open_with_arch:
line 471: /dev/pty1<0x8000086F0> usecount + 1 = 4
--- Process 3968 (pid: 14876), exception c0000008 at 00007ff81682416a
--- Process 3968 (pid: 14876), exception c0000008 at 00007ff81682416a
...
"... found an archetype for (null) ..." <== Hmm...
--
Regards,
Christian
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