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um: Fix waitpid() usage in helper code 

If UML is executing a helper program it is using
waitpid() with the __WCLONE flag to wait for the program
as the helper is executed from a clone()'ed thread.
While using __WCLONE is perfectly fine for clone()'ed
childs it won't detect terminated childs if the helper
has issued an execve().

We have to use __WALL to wait for both clone()'ed and
regular childs to detect the termination before and
after an execve().

Reported-and-tested-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
hifive-unleashed-5.1
Richard Weinberger 2015-08-09 21:49:07 +02:00
parent 37e81a016c
commit 6b1873371c
1 changed files with 3 additions and 3 deletions
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6
arch/um/os-Linux/helper.c
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@ -96,7 +96,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
"ret = %d\n", -n);
ret = n;
}
CATCH_EINTR(waitpid(pid, NULL, __WCLONE));
CATCH_EINTR(waitpid(pid, NULL, __WALL));
}
out_free2:
@ -129,7 +129,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
return err;
}
if (stack_out == NULL) {
CATCH_EINTR(pid = waitpid(pid, &status, __WCLONE));
CATCH_EINTR(pid = waitpid(pid, &status, __WALL));
if (pid < 0) {
err = -errno;
printk(UM_KERN_ERR "run_helper_thread - wait failed, "
@ -148,7 +148,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
int helper_wait(int pid)
{
int ret, status;
int wflags = __WCLONE;
int wflags = __WALL;
CATCH_EINTR(ret = waitpid(pid, &status, wflags));
if (ret < 0) {