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author | Lepton Wu <ytht.net@gmail.com> | 2007-10-16 01:27:35 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 09:43:09 -0700 |
commit | a24864a1d52a97e345a6bd4862a057f98364d098 (patch) | |
tree | a1c07cfa857d818d4a58217fdec40d765d349a4f /arch | |
parent | cb8fa61c2b8b29d422d7310f064d60022f18f89b (diff) | |
download | op-kernel-dev-a24864a1d52a97e345a6bd4862a057f98364d098.zip op-kernel-dev-a24864a1d52a97e345a6bd4862a057f98364d098.tar.gz |
uml: definitively kill subprocesses on panic
In a stock 2.6.22.6 kernel, poweroff a user mode linux guest (2.6.22.6 running
in skas0 mode) will halt the host linux. I think the reason is the kernel
thread abort because of a bug. Then the sys_reboot in process of user mode
linux guest is not trapped by the user mode linux kernel and is executed by
host. I think it is better to make sure all of our children process to quit
when user mode linux kernel abort.
[ jdike - the kernel process needs to ignore SIGTERM, plus the waitpid/kill
loop is needed to make sure that all of our children are dead before the
kernel exits ]
Signed-off-by: Lepton Wu <ytht.net@gmail.com>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/um/os-Linux/skas/process.c | 2 | ||||
-rw-r--r-- | arch/um/os-Linux/util.c | 38 |
2 files changed, 39 insertions, 1 deletions
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c index e60d6e6..d77c81d 100644 --- a/arch/um/os-Linux/skas/process.c +++ b/arch/um/os-Linux/skas/process.c @@ -177,7 +177,7 @@ static int userspace_tramp(void *stack) ptrace(PTRACE_TRACEME, 0, 0, 0); - init_new_thread_signals(); + signal(SIGTERM, SIG_DFL); err = set_interval(); if (err) panic("userspace_tramp - setting timer failed, errno = %d\n", diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c index 7cbcf48..ef09543 100644 --- a/arch/um/os-Linux/util.c +++ b/arch/um/os-Linux/util.c @@ -105,6 +105,44 @@ int setjmp_wrapper(void (*proc)(void *, void *), ...) void os_dump_core(void) { + int pid; + signal(SIGSEGV, SIG_DFL); + + /* + * We are about to SIGTERM this entire process group to ensure that + * nothing is around to run after the kernel exits. The + * kernel wants to abort, not die through SIGTERM, so we + * ignore it here. + */ + + signal(SIGTERM, SIG_IGN); + kill(0, SIGTERM); + /* + * Most of the other processes associated with this UML are + * likely sTopped, so give them a SIGCONT so they see the + * SIGTERM. + */ + kill(0, SIGCONT); + + /* + * Now, having sent signals to everyone but us, make sure they + * die by ptrace. Processes can survive what's been done to + * them so far - the mechanism I understand is receiving a + * SIGSEGV and segfaulting immediately upon return. There is + * always a SIGSEGV pending, and (I'm guessing) signals are + * processed in numeric order so the SIGTERM (signal 15 vs + * SIGSEGV being signal 11) is never handled. + * + * Run a waitpid loop until we get some kind of error. + * Hopefully, it's ECHILD, but there's not a lot we can do if + * it's something else. Tell os_kill_ptraced_process not to + * wait for the child to report its death because there's + * nothing reasonable to do if that fails. + */ + + while ((pid = waitpid(-1, NULL, WNOHANG)) > 0) + os_kill_ptraced_process(pid, 0); + abort(); } |