/* tid is the actual task/thread id (née pid, stored as ->pid),
pid/tgid is that 2.6 thread group id crap (stored as ->tgid) */
asmlinkage long sys_vperfctr_open(int tid, int creat)
{
struct file *filp;
struct task_struct *tsk;
struct vperfctr *perfctr;
int err;
int fd;
if (!vperfctr_fs_init_done())
return -ENODEV;
filp = vperfctr_get_filp();
if (!filp)
return -ENOMEM;
err = fd = get_unused_fd();
if (err < 0)
goto err_filp;
perfctr = NULL;
if (creat) {
perfctr = get_empty_vperfctr(); /* may sleep */
if (IS_ERR(perfctr)) {
err = PTR_ERR(perfctr);
goto err_fd;
}
}
tsk = current;
if (tid != 0 && tid != tsk->pid) { /* remote? */
// tasklist_lock is to access the linked list of task_struct structures exclusively
read_lock(&tasklist_lock);
//tsk = find_task_by_pid(tid);
tsk = find_task_by_pid_ns(tid, current->nsproxy->pid_ns);
if (tsk)
get_task_struct(tsk);
read_unlock(&tasklist_lock);
err = -ESRCH;
if (!tsk)
goto err_perfctr;
err = ptrace_check_attach(tsk, 0);
if (err < 0)
goto err_tsk;
}
if (creat) {
/* check+install must be atomic to prevent remote-control races */
task_lock(tsk);
if (!tsk->thread.perfctr) {
perfctr->owner = tsk;
tsk->thread.perfctr = perfctr;
err = 0;
} else
err = -EEXIST;
task_unlock(tsk);
if (err)
goto err_tsk;
} else {
perfctr = tsk->thread.perfctr;
/* XXX: Old API needed to allow NULL perfctr here.
Do we want to keep or change that rule? */
}
filp->private_data = perfctr;
if (perfctr)
atomic_inc(&perfctr->count);
if (tsk != current)
put_task_struct(tsk);
#if 0
if (perfctr) {
printk ("sys_vperfctr_open(): fd = %d, perfctr is NOT null\n", fd);
}
else {
printk ("sys_vperfctr_open(): fd = %d, perfctr is null\n", fd);
}
#endif
fd_install(fd, filp);
return fd;
err_tsk:
if (tsk != current)
put_task_struct(tsk);
err_perfctr:
if (perfctr) /* can only occur if creat != 0 */
put_vperfctr(perfctr);
err_fd:
put_unused_fd(fd);
err_filp:
fput(filp);
return err;
}
/* tid is the actual task/thread id (née pid, stored as ->pid),
pid/tgid is that 2.6 thread group id crap (stored as ->tgid) */
int vperfctr_attach(int tid, int creat)
{
struct file *filp;
struct task_struct *tsk;
struct vperfctr *perfctr;
int err;
int fd;
filp = vperfctr_get_filp();
if (!filp)
return -ENOMEM;
err = fd = get_unused_fd();
if (err < 0)
goto err_filp;
perfctr = NULL;
if (creat) {
perfctr = get_empty_vperfctr(); /* may sleep */
if (IS_ERR(perfctr)) {
err = PTR_ERR(perfctr);
goto err_fd;
}
}
tsk = current;
if (tid != 0 && tid != task_pid_vnr(tsk)) { /* remote? */
vperfctr_lock_find_task_by_vpid();
tsk = find_task_by_vpid(tid);
if (tsk)
get_task_struct(tsk);
vperfctr_unlock_find_task_by_vpid();
err = -ESRCH;
if (!tsk)
goto err_perfctr;
err = ptrace_check_attach(tsk, 0);
if (err < 0)
goto err_tsk;
}
if (creat) {
/* check+install must be atomic to prevent remote-control races */
vperfctr_task_lock(tsk);
if (!tsk->thread.perfctr) {
perfctr->owner = tsk;
tsk->thread.perfctr = perfctr;
err = 0;
} else
err = -EEXIST;
vperfctr_task_unlock(tsk);
if (err)
goto err_tsk;
} else {
perfctr = tsk->thread.perfctr;
/* PERFCTR_ABI and PERFCTR_INFO don't need the perfctr.
Hence no non-NULL check here. */
}
filp->private_data = perfctr;
if (perfctr)
atomic_inc(&perfctr->count);
if (tsk != current)
put_task_struct(tsk);
fd_install(fd, filp);
return fd;
err_tsk:
if (tsk != current)
put_task_struct(tsk);
err_perfctr:
if (perfctr) /* can only occur if creat != 0 */
put_vperfctr(perfctr);
err_fd:
put_unused_fd(fd);
err_filp:
fput(filp);
return err;
}
