/** Deallocate the memory that was allocated by rwlock_initialize(). */
static void rwlock_cleanup(struct rwlock_info* p)
{
struct rwlock_thread_info* q;
tl_assert(p);
if (s_trace_rwlock)
{
VG_(message)(Vg_UserMsg,
"[%d/%d] rwlock_destroy 0x%lx",
VG_(get_running_tid)(),
thread_get_running_tid(),
p->a1);
}
if (rwlock_is_locked(p))
{
RwlockErrInfo REI = { p->a1 };
VG_(maybe_record_error)(VG_(get_running_tid)(),
RwlockErr,
VG_(get_IP)(VG_(get_running_tid)()),
"Destroying locked rwlock",
&REI);
}
VG_(OSetGen_ResetIter)(p->thread_info);
for ( ; (q = VG_(OSetGen_Next)(p->thread_info)); q++)
{
vc_cleanup(&q->vc);
}
VG_(OSetGen_Destroy)(p->thread_info);
}
static inline void __preempt_write_lock(rwlock_t *lock)
{
if (preempt_count() > 1) {
_raw_write_lock(lock);
return;
}
do {
preempt_enable();
while (rwlock_is_locked(lock))
cpu_relax();
preempt_disable();
} while (!_raw_write_trylock(lock));
}
int ptrace_attach(struct task_struct *task)
{
int retval;
retval = -EPERM;
if (task->pid <= 1)
goto out;
if (task == current)
goto out;
repeat:
/*
* Nasty, nasty.
*
* We want to hold both the task-lock and the
* tasklist_lock for writing at the same time.
* But that's against the rules (tasklist_lock
* is taken for reading by interrupts on other
* cpu's that may have task_lock).
*/
task_lock(task);
local_irq_disable();
if (!write_trylock(&tasklist_lock)) {
local_irq_enable();
task_unlock(task);
do {
cpu_relax();
} while (rwlock_is_locked(&tasklist_lock));
goto repeat;
}
if (!task->mm)
goto bad;
if(((current->uid != task->euid) ||
(current->uid != task->suid) ||
(current->uid != task->uid) ||
(current->gid != task->egid) ||
(current->gid != task->sgid) ||
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
goto bad;
rmb();
if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
goto bad;
/* the same process cannot be attached many times */
if (task->ptrace & PT_PTRACED)
goto bad;
retval = security_ptrace(current, task);
if (retval)
goto bad;
/* Go */
task->ptrace |= PT_PTRACED | ((task->real_parent != current)
? PT_ATTACHED : 0);
if (capable(CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
__ptrace_link(task, current);
force_sig_specific(SIGSTOP, task);
bad:
write_unlock_irq(&tasklist_lock);
task_unlock(task);
out:
return retval;
}
