I noticed that Tomoyo doesn't build on Alpha because Tomoyo tries to
call sys_getpid() and sys_getppid(). That's a bug in Tomoyo, but when I
looked at why Alpha is different I found that the implementation of
getxpid() hasn't been kept in sync getppid() for other architectures and
is presumably now incorrect.
sys_getppid():
rcu_read_lock();
pid = task_tgid_vnr(current->real_parent);
rcu_read_unlock();
task_tgid_vnr(current->real_parent) expands through various inline
functions to:
pid_nr_ns(current->real_parent->group_leader->pids[PIDTYPE_PID].pid,
current->nsproxy->pid_ns)
sys_getxpid():
/* See linux/kernel/timer.c sys_getppid for discussion
about this loop. */
ldq $3, TASK_GROUP_LEADER($2)
ldq $4, TASK_REAL_PARENT($3)
ldl $0, TASK_TGID($2)
1: ldl $1, TASK_TGID($4)
#ifdef CONFIG_SMP
mov $4, $5
mb
ldq $3, TASK_GROUP_LEADER($2)
ldq $4, TASK_REAL_PARENT($3)
cmpeq $4, $5, $5
beq $5, 1b
#endif
The comment is obviously out-of-date. This isn't following RCU protocol
and it isn't namespace-aware. I think it needs to be turned into a
wrapper for the generic code.
Ben.
--
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.
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