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um: Cleanup SIGTERM handling

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Richard reported that some UML processes survive if the UML
main process receives a SIGTERM.
This issue was caused by a wrongly placed signal(SIGTERM, SIG_DFL)
in init_new_thread_signals().
It disabled the UML exit handler accidently for some processes.
The correct solution is to disable the fatal handler for all
UML helper threads/processes.
Such that last_ditch_exit() does not get called multiple times
and all processes can exit due to SIGTERM.

Reported-and-tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Richard Weinberger 2013-08-18 13:30:08 +02:00
parent bc1d72e73b
commit 91d44ff860
8 changed files with 16 additions and 12 deletions
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1
arch/um/drivers/ubd.h
View File

@ -7,7 +7,6 @@
#ifndef __UM_UBD_USER_H
#define __UM_UBD_USER_H
extern void ignore_sigwinch_sig(void);
extern int start_io_thread(unsigned long sp, int *fds_out);
extern int io_thread(void *arg);
extern int kernel_fd;

3
arch/um/drivers/ubd_kern.c
View File

@ -1476,7 +1476,8 @@ int io_thread(void *arg)
struct io_thread_req *req;
int n;
ignore_sigwinch_sig();
os_fix_helper_signals();
while(1){
n = os_read_file(kernel_fd, &req,
sizeof(struct io_thread_req *));

5
arch/um/drivers/ubd_user.c
View File

@ -21,11 +21,6 @@
#include "ubd.h"
#include <os.h>
void ignore_sigwinch_sig(void)
{
signal(SIGWINCH, SIG_IGN);
}
int start_io_thread(unsigned long sp, int *fd_out)
{
int pid, fds[2], err;

1
arch/um/include/shared/os.h
View File

@ -235,6 +235,7 @@ extern void setup_machinename(char *machine_out);
extern void setup_hostinfo(char *buf, int len);
extern void os_dump_core(void) __attribute__ ((noreturn));
extern void um_early_printk(const char *s, unsigned int n);
extern void os_fix_helper_signals(void);
/* time.c */
extern void idle_sleep(unsigned long long nsecs);

5
arch/um/os-Linux/aio.c
View File

@ -104,8 +104,7 @@ static int aio_thread(void *arg)
struct io_event event;
int err, n, reply_fd;
signal(SIGWINCH, SIG_IGN);
os_fix_helper_signals();
while (1) {
n = io_getevents(ctx, 1, 1, &event, NULL);
if (n < 0) {
@ -173,7 +172,7 @@ static int not_aio_thread(void *arg)
struct aio_thread_reply reply;
int err;
signal(SIGWINCH, SIG_IGN);
os_fix_helper_signals();
while (1) {
err = read(aio_req_fd_r, &req, sizeof(req));
if (err != sizeof(req)) {

1
arch/um/os-Linux/process.c
View File

@ -294,5 +294,4 @@ void init_new_thread_signals(void)
signal(SIGHUP, SIG_IGN);
set_handler(SIGIO);
signal(SIGWINCH, SIG_IGN);
signal(SIGTERM, SIG_DFL);
}

2
arch/um/os-Linux/sigio.c
View File

@ -55,7 +55,7 @@ static int write_sigio_thread(void *unused)
int i, n, respond_fd;
char c;
signal(SIGWINCH, SIG_IGN);
os_fix_helper_signals();
fds = &current_poll;
while (1) {
n = poll(fds->poll, fds->used, -1);

10
arch/um/os-Linux/util.c
View File

@ -94,6 +94,16 @@ static inline void __attribute__ ((noreturn)) uml_abort(void)
exit(127);
}
/*
* UML helper threads must not handle SIGWINCH/INT/TERM
*/
void os_fix_helper_signals(void)
{
signal(SIGWINCH, SIG_IGN);
signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
}
void os_dump_core(void)
{
int pid;