Tue 03 Sep 2013 05:44:02 PM UTC, original submission:
This was filed in Red Hat bugzilla here:
https://bugzilla.redhat.com/show_bug.cgi?id=885474
To reproduce this, use the following Makefile:
default:
/home/petr/src/make/build/make -f Makefile2
And the following Makefile2 (note: the path in vpath must exist):
vpath %.c /home/petr/
foo:
Then run make:
$ make -j 2
/home/petr/src/make/build/make -f Makefile2
make[1]: Entering directory `/home/petr/tmp/tst'
make[1]: warning: jobserver unavailable: using -j1. Add `+' to parent make rule.
make[1]: *** INTERNAL: readdir: Bad file descriptor
. Stop.
make[1]: Makefile2: Field 'stem' not cached: Makefile2
make[1]: Leaving directory `/home/petr/tmp/tst'
make: *** [default] Error 2
The following excerpt from an ltrace run illustrates the problem:
18706 16:46:43.945567 opendir("/home/petr" <unfinished ...>
18706 16:46:43.945713 SYS_open("/home/petr", 591872, 0172204710) = 4
18706 16:46:43.945785 SYS_brk(0) = 0x1e9d000
18706 16:46:43.945824 SYS_brk(0x1ec5000) = 0x1ec5000
18706 16:46:43.945870 <... opendir resumed> ) = { 4 }
[...]
18706 16:46:44.347777 close(4 <unfinished ...>
18706 16:46:44.347882 SYS_close(4) = 0
18706 16:46:44.347927 <... close resumed> ) = 0
[...]
18706 16:46:45.718922 readdir({ 4 } <unfinished ...>
18706 16:46:45.719037 SYS_getdents(4, 0x161f008, 32768) = -9
18706 16:46:45.719103 <... readdir resumed> ) = 0
The problem arises when parental make passes down jobserver FDs in the environment, but the child make is not run as part of this jobsever batch. Child make notices JOB_FDS numbers passed down, and tries to dup, which fails, because JOB_FDS[0] is invalid. In then switches to -j1, and proceeds to close JOB_FDS. But in the meantime make managed to reuse one of those descriptors for a directory stream for vpath. When that is closed it later causes the error message seen in the subject.
The immediate idea is not to close JOB_FDS if the dup fails. That's certainly part of the solution (because otherwise we end up calling close over invalid file descriptors). But that it fails is pure luck: make gets FD 3 for Makefile2, then FD 4 for vpath dirstream, and then closes 3 after it's done with it. Had --jobserver-fds been 4 and 5, we would dup it without trouble.
But perhaps it's possible to move read_all_makefiles down beyond the JOB_FDS business. Then there would be no file operations except those in the dynamic linker, and those don't leak descriptors. Then we can use the dup as a reliable test. However I don't know whether there are interactions that I don't see, and whether it's safe and desirable to postpone the parsing to a later time like this. The test suite passes with this FWIW.
|